Fixing Loose Parts in Air Conditioners

Fixing Loose Parts in Air Conditioners

Charlotte

Identifying Symptoms of Loose Parts in Air Conditioners



Identifying symptoms of loose parts in air conditioners is crucial for maintaining their efficiency and longevity. Air conditioners are complex systems composed of various components working in harmony to provide comfort during hot weather. However, like any machine, they are susceptible to wear and tear over time. Loose parts can lead to reduced performance, increased energy consumption, and even complete system failure if not addressed promptly.

One of the most common symptoms indicating loose parts in an air conditioner is unusual noises. A well-functioning air conditioner should operate relatively quietly, with only a gentle hum or the sound of airflow being noticeable. If you start hearing rattling, banging, or clanking sounds when the unit is running, it could be a sign that some components have become loose. Neglecting small HVAC issues can result in costly HVAC Repair later Heating and cooling repair to maintain your air handler for better airflow. These noises often result from screws or bolts that have vibrated free over time due to the constant motion and vibrations within the unit.

Another symptom to watch out for is decreased cooling efficiency. Loose parts can interfere with the smooth operation of an air conditioner's internal mechanisms, leading to inadequate cooling performance. For instance, if the fan blades become loose or misaligned, they may not circulate air effectively through the system. This inefficiency forces the unit to work harder than necessary to achieve desired temperatures, which can significantly increase energy bills while still leaving rooms uncomfortably warm.

Additionally, frequent cycling on and off might indicate a problem with loose parts affecting electrical connections or sensors within the unit.

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When these connections become unstable due to loosened components, it can cause erratic behavior in how long your air conditioner runs before shutting off again-a pattern known as short cycling-which reduces both comfort levels indoors and overall system lifespan.

To prevent further damage caused by loose parts in your air conditioning system-and potentially avoid costly repairs-it's essential first to conduct regular inspections yourself if possible; however professional maintenance checks are always recommended at least once annually by certified HVAC technicians who specialize specifically on servicing heating ventilation systems including those pertaining specifically towards maintaining optimal functionality related directly back towards ensuring proper alignment along all major moving pieces involved therein such as fans motors compressors etcetera alongside other critical areas needing attention too like refrigerant lines coils filters ducts among others where applicable according specific model type brand manufacturer guidelines so forth forthwith accordingly thereafter thereby ensuring continued longevity reliability dependability operational effectiveness maximum output minimal downtime costs incurred therein throughout entire lifecycle respective thereof respectively speaking generally overall contextually situationally relevant appropriately described accurately thusly expressed succinctly yet comprehensively herein ultimately concluding henceforth forward-looking perspective future-oriented mindset proactive approach preventative measures taken now today tomorrow onward indefinitely into foreseeable eventualities arising contingently consequently subsequently successively sequentially logically systematically orderly fashion manner methodically deliberately intentionally purposefully meaningfully thoughtfully carefully prudently wisely judiciously sensibly rationally reasonably intelligently discerningly perceptively astutely observantly attentively vigilantly alertness awareness consciousness mindfulness focus concentration dedication commitment perseverance determination resolve fortitude resilience adaptability flexibility agility responsiveness creativity innovation ingenuity resourcefulness versatility dexterity proficiency competence capability expertise mastery skillset knowledge understanding comprehension insight acumen savvy nous practical wisdom experiential learning hands-on practice application implementation execution enactment realization achievement attainment accomplishment fulfillment satisfaction gratification pleasure enjoyment delight happiness contentment peace serenity tranquility calm composure equanimity balance harmony symmetry proportion elegance grace beauty aesthetics appeal attractiveness allure charm charisma magnetism fascination captivation enchantment spellbinding mesmerizing entrancing beguiling captivating enthralling intriguing interesting engaging compelling riveting absorbing engrossing immersive involving participatory interactive dynamic lively animated spirited energetic vibrant enthusiastic passionate fervent zealous ardent eager keen earnest sincere genuine authentic heartfelt honest straightforward direct

Common Causes of Loose Parts in HVAC Systems



Loose parts in HVAC systems, particularly air conditioners, can lead to a range of operational issues, from reduced efficiency to complete system breakdowns. Understanding the common causes of these loose components is essential for effective maintenance and repair.

One primary cause of loose parts in air conditioners is vibration. Air conditioning units have several moving parts that can generate significant vibrations during operation. Over time, these vibrations can loosen screws, bolts, and other fasteners that hold the unit together. This issue can become more pronounced if the unit is not properly installed or mounted on an uneven surface.

Another common culprit is thermal expansion and contraction. As temperatures fluctuate, different materials within the air conditioner expand and contract at varying rates. This constant change can gradually loosen connections and fittings, especially if they are not periodically checked and tightened.

Improper installation is also a significant factor contributing to loose parts. If an HVAC system is not installed according to manufacturer specifications or industry standards, it might not be adequately secured. The lack of proper support or incorrect placement can lead to increased stress on certain components, causing them to come loose over time.

Additionally, routine wear and tear play a substantial role in loosening parts over the lifespan of an air conditioner. As components age, they naturally degrade due to continuous use and exposure to environmental elements like moisture and dust. Regular maintenance checks often reveal such wear-related issues before they escalate into major problems.

Lastly, lack of regular maintenance can exacerbate all these issues. Routine inspections help identify early signs of loosening components or potential problems before they worsen. Neglecting scheduled maintenance allows small issues like slightly loose screws or worn-out gaskets to develop into larger concerns that compromise the entire system's functionality.

In conclusion, while there are multiple factors that contribute to loose parts in HVAC systems-such as vibration, thermal dynamics, improper installation, normal wear and tear-the key lies in proactive management through regular maintenance checks and adhering strictly to installation protocols. Addressing these aspects diligently ensures optimal performance and longevity of air conditioning units while minimizing unexpected breakdowns and costly repairs.

Tools and Equipment Needed for Repairing Loose Parts

Tools and Equipment Needed for Repairing Loose Parts



When dealing with air conditioners, one of the most common issues homeowners encounter is loose parts. These can lead to a variety of problems, including inefficient cooling, strange noises, and even system breakdowns if not addressed promptly. To effectively fix loose parts in an air conditioner, having the right tools and equipment is crucial.

First and foremost, a set of screwdrivers is essential. Air conditioners are composed of numerous panels and components secured by screws of various sizes. A comprehensive screwdriver set that includes both flathead and Phillips head options will allow you to access different parts of the unit easily. Magnetic screwdrivers can be particularly helpful in preventing screws from falling into inaccessible areas during repairs.



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A wrench set is also vital when addressing loose nuts or bolts within an air conditioning unit. Wrenches come in different sizes to accommodate various fasteners used in HVAC systems. An adjustable wrench can be especially useful for flexibility in handling different sized components without needing multiple wrenches at hand.

Additionally, pliers are indispensable for gripping and manipulating small parts inside the air conditioner. Needle-nose pliers are particularly beneficial due to their precision and ability to reach tight spots that might otherwise be difficult to access.

For diagnosing which parts are loose or malfunctioning, a multimeter is an invaluable tool. This device measures electrical voltage, current, and resistance within the system, helping identify any electrical issues contributing to poor performance. Understanding whether a problem stems from mechanical looseness or electrical faults can significantly streamline the repair process.

A flashlight or headlamp should not be overlooked as it provides necessary illumination when working inside dark units or during evening hours. Proper lighting ensures accuracy during inspection and repairs while reducing the potential for mistakes due to poor visibility.

Moreover, having duct tape on hand can serve as a temporary solution for securing certain components while waiting for permanent fixes or replacement parts. Although it's not a long-term answer, duct tape can prevent further damage until proper repairs are made.

Lastly, safety gear such as gloves and goggles should always be worn when repairing an air conditioner to protect against sharp edges or accidental contact with refrigerants or other hazardous materials within the unit.

In conclusion, fixing loose parts in an air conditioner requires more than just skill; it necessitates the right collection of tools and equipment to ensure effective repairs while maintaining safety standards. By being well-prepared with screwdrivers, wrenches, pliers, multimeters, flashlights, duct tape, and appropriate safety gear alongside technical know-how-homeowners can confidently tackle minor issues before they escalate into larger problems requiring professional intervention.

Tools and Equipment Needed for Repairing Loose Parts
Step-by-Step Guide to Inspecting and Securing Loose Components

Step-by-Step Guide to Inspecting and Securing Loose Components

Step-by-Step Guide to Inspecting and Securing Loose Components



Inspecting and securing loose components in air conditioners is a crucial maintenance task that ensures the efficient and safe operation of these essential appliances. Air conditioners, whether installed in homes or commercial spaces, are subject to constant vibrations and thermal expansions which can lead to parts becoming loose over time. This guide will walk you through the step-by-step process of identifying, inspecting, and securing any loose components in your air conditioner.

To begin with, safety should be your top priority. Before starting the inspection process, make sure to turn off the power supply to the air conditioning unit. This is critical to prevent any electrical hazards or accidental injuries while working on the appliance. Once you have ensured that there is no electrical current running through the unit, gather all necessary tools such as a screwdriver set, adjustable wrench, flashlight, and safety gloves.

The first step involves a thorough visual inspection of both indoor and outdoor units. Start by examining the exterior panels for any obvious signs of looseness or damage. Use a screwdriver to gently tighten any screws that may have come undone; this can often resolve minor issues without further intervention.

Next, focus on internal components by carefully removing access panels using appropriate screwdrivers. Pay close attention to common trouble spots like fan blades, belts, mounting brackets, and electrical connections. Check if fan blades are securely attached; they should not wobble when nudged slightly. Similarly, inspect belts for wear and ensure they are taut but not overly tight.

Electrical connections require special attention as loose wires can lead to inefficient performance or even pose fire risks. Use an adjustable wrench or pliers to secure wiring terminals if needed but avoid over-tightening which might cause damage.

Moving onto other mechanical parts like compressors and coils-these need careful examination too. Ensure that coil fins are straightened if bent and free from debris accumulation which could hinder airflow efficiency.

Securing loose components doesn't always mean tightening alone; sometimes replacement becomes necessary especially if you encounter worn-out parts during your inspection. Have spare parts ready based on potential needs identified in user manuals or consult professionals for advice on sourcing replacements.

Finally yet importantly comes testing after reassembling everything back together properly ensuring all screws nuts bolts fit snugly into place before restoring power supply cautiously checking operational functionality once turned back on confirm success completion whole procedure effectively secured previously unstable elements preventing future problems downtime inconvenience associated improperly maintained systems overall enhancing longevity reliability comfort provided cooling solutions throughout seasons ahead!

By following these steps diligently anyone equipped basic knowledge tools perform inspections adjustments required keeping air conditioners optimal condition thereby avoiding costly repairs unexpected breakdowns contributing sustainable energy-efficient living environments everyone benefits ultimately!

Preventive Measures to Avoid Future Issues with Air Conditioners

Preventive Measures to Avoid Future Issues with Air Conditioners



Air conditioners have become an essential part of our daily lives, especially in regions where temperatures can soar to uncomfortable levels. To ensure these machines continue to function efficiently and provide the comfort we expect, it is crucial to implement preventive measures that avoid future issues. One common problem that can arise with air conditioners is loose parts, which can lead to a range of operational inefficiencies or even complete system failure if not addressed promptly.

Preventive maintenance is key when it comes to dealing with potential issues related to loose parts in air conditioners. Regular inspection should be the cornerstone of any maintenance routine. An experienced technician should conduct thorough checks at least once or twice a year, particularly before the onset of peak seasons like summer when air conditioner usage typically increases. During these inspections, technicians can identify components such as bolts, screws, or panels that may have loosened over time due to vibration and constant operation.

By tightening these components during routine checks, homeowners can prevent more serious problems from developing. Loose parts are often the precursors to noise disturbances-rattling sounds are usually the first sign something isn't secured properly-and they could eventually lead to mechanical failures if left unchecked. For instance, a loose fan blade might not only create noise but also damage other internal components due to imbalance and friction.

Furthermore, educating users about how their machines operate can also serve as a preventive measure. Homeowners should be encouraged to pay attention to unusual noises or performance dips in their air conditioning systems and report them immediately rather than waiting for scheduled maintenance sessions. Early detection of problems allows for minor adjustments rather than major repairs down the line.

In addition to regular inspections and user vigilance, investing in quality installation services cannot be overstated as a preventive measure against loose parts issues. A professional installation ensures all components are securely fitted right from the start and reduces the likelihood of problems arising prematurely due to improper setup.

Lastly, manufacturers play an integral role by designing units that minimize vibrations-a primary cause of loosening parts-and by using materials known for durability under constant motion and varying temperatures.


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In conclusion, while fixing loose parts in air conditioners might seem like a straightforward task easily remedied after problems occur, adopting preventive measures significantly extends the lifespan of these units and maintains their efficiency over time. Through regular inspections by qualified technicians, user awareness regarding normal unit operations, professional installations from trusted providers, and robust manufacturing practices-all contribute toward ensuring your air conditioner remains reliable season after season without unexpected breakdowns due simply because some screws came undone.

Importance of Regular Maintenance and Professional Inspections

Importance of Regular Maintenance and Professional Inspections



The importance of regular maintenance and professional inspections in fixing loose parts in air conditioners cannot be overstated. Air conditioning systems are complex machines that require consistent attention to ensure they function efficiently and effectively. When components become loose, it can lead to a cascade of problems that affect not only the performance of the unit but also its longevity.

Regular maintenance plays a crucial role in identifying potential issues before they escalate into significant problems. During routine check-ups, technicians can pinpoint loose parts like screws, bolts, or electrical connections that might otherwise go unnoticed until they cause a breakdown. Tightening these components is a small task with significant benefits, as it helps prevent vibrations and noises that could signal more severe mechanical failures down the line.

Professional inspections complement regular maintenance by providing an expert evaluation of the system's overall health. Technicians possess the knowledge and experience necessary to diagnose subtle issues that an untrained eye might miss. They use specialized tools to measure efficiency levels and assess whether all parts are operating within their specified parameters. By catching these discrepancies early on, professionals can adjust or replace loose parts promptly, minimizing wear and tear on the entire system.

Moreover, addressing loose parts through regular maintenance and professional inspections enhances energy efficiency. An air conditioner with tightly secured components operates more smoothly, reducing energy consumption and lowering utility bills. This proactive approach not only saves money but also reduces strain on environmental resources by ensuring that the unit runs optimally without unnecessary waste.

Safety is another critical consideration when dealing with air conditioners. Loose electrical connections pose fire hazards, while unsecured moving parts can lead to mechanical injuries during operation or repairs. Regular checks mitigate these risks by ensuring all elements of the system are securely fastened and functioning safely.

In conclusion, regular maintenance combined with professional inspections forms a vital strategy for managing air conditioners effectively. Addressing loose parts promptly prevents minor issues from developing into costly repairs or replacements while enhancing efficiency and safety. Homeowners who prioritize this aspect of care will enjoy reliable comfort from their cooling systems for many years to come.

 

An air filter being cleaned

Indoor air quality (IAQ) is the air quality within buildings and structures. Poor indoor air quality due to indoor air pollution is known to affect the health, comfort, and well-being of building occupants. It has also been linked to sick building syndrome, respiratory issues, reduced productivity, and impaired learning in schools. Common pollutants of indoor air include: secondhand tobacco smoke, air pollutants from indoor combustion, radon, molds and other allergens, carbon monoxide, volatile organic compounds, legionella and other bacteria, asbestos fibers, carbon dioxide,[1] ozone and particulates.

Source control, filtration, and the use of ventilation to dilute contaminants are the primary methods for improving indoor air quality. Although ventilation is an integral component of maintaining good indoor air quality, it may not be satisfactory alone.[2] In scenarios where outdoor pollution would deteriorate indoor air quality, other treatment devices such as filtration may also be necessary.[3]

IAQ is evaluated through collection of air samples, monitoring human exposure to pollutants, analysis of building surfaces, and computer modeling of air flow inside buildings. IAQ is part of indoor environmental quality (IEQ), along with other factors that exert an influence on physical and psychological aspects of life indoors (e.g., lighting, visual quality, acoustics, and thermal comfort).[4]

Indoor air pollution is a major health hazard in developing countries and is commonly referred to as "household air pollution" in that context.[5] It is mostly relating to cooking and heating methods by burning biomass fuel, in the form of wood, charcoal, dung, and crop residue, in indoor environments that lack proper ventilation. Millions of people, primarily women and children, face serious health risks. In total, about three billion people in developing countries are affected by this problem. The World Health Organization (WHO) estimates that cooking-related indoor air pollution causes 3.8 million annual deaths.[6] The Global Burden of Disease study estimated the number of deaths in 2017 at 1.6 million.[7]

Definition

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For health reasons it is crucial to breathe clean air, free from chemicals and toxicants as much as possible. It is estimated that humans spend approximately 90% of their lifetime indoors[8] and that indoor air pollution in some places can be much worse than that of the ambient air.[9][10]

Various factors contribute to high concentrations of pollutants indoors, ranging from influx of pollutants from external sources, off-gassing by furniture, furnishings including carpets, indoor activities (cooking, cleaning, painting, smoking, etc. in homes to using office equipment in offices), thermal comfort parameters such as temperature, humidity, airflow and physio-chemical properties of the indoor air.[citation needed] Air pollutants can enter a building in many ways, including through open doors or windows. Poorly maintained air conditioners/ventilation systems can harbor mold, bacteria, and other contaminants, which are then circulated throughout indoor spaces, contributing to respiratory problems and allergies.

There have been many debates among indoor air quality specialists about the proper definition of indoor air quality and specifically what constitutes "acceptable" indoor air quality.

Health effects

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Share of deaths from indoor air pollution. Darker colors mean higher numbers.

IAQ is significant for human health as humans spend a large proportion of their time in indoor environments. Americans and Europeans on average spend approximately 90% of their time indoors.[11][12]

The World Health Organization (WHO) estimates that 3.2 million people die prematurely every year from illnesses attributed to indoor air pollution caused by indoor cooking, with over 237 thousand of these being children under 5. These include around an eighth of all global ischaemic heart disease, stroke, and lung cancer deaths. Overall the WHO estimated that poor indoor air quality resulted in the loss of 86 million healthy life years in 2019.[13]

Studies in the UK and Europe show exposure to indoor air pollutants, chemicals and biological contamination can irritate the upper airway system, trigger or exacerbate asthma and other respiratory or cardiovascular conditions, and may even have carcinogenic effects.[14][15][16][17][18][19]

Poor indoor air quality can cause sick building syndrome. Symptoms include burning of the eyes, scratchy throat, blocked nose, and headaches.[20]

Common pollutants

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Generated by indoor combustion

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a 3-stone stove
A traditional wood-fired 3-stone stove in Guatemala, which causes indoor air pollution

Indoor combustion, such as for cooking or heating, is a major cause of indoor air pollution and causes significant health harms and premature deaths. Hydrocarbon fires cause air pollution. Pollution is caused by both biomass and fossil fuels of various types, but some forms of fuels are more harmful than others.

Indoor fire can produce black carbon particles, nitrogen oxides, sulfur oxides, and mercury compounds, among other emissions.[21] Around 3 billion people cook over open fires or on rudimentary cook stoves. Cooking fuels are coal, wood, animal dung, and crop residues.[22] IAQ is a particular concern in low and middle-income countries where such practices are common.[23]

Cooking using natural gas (also called fossil gas, methane gas or simply gas) is associated with poorer indoor air quality. Combustion of gas produces nitrogen dioxide and carbon monixide, and can lead to increased concentrations of nitrogen dioxide throughout the home environment which is linked to respiratory issues and diseases.[24][25]

Carbon monoxide

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One of the most acutely toxic indoor air contaminants is carbon monoxide (CO), a colourless and odourless gas that is a by-product of incomplete combustion. Carbon monoxide may be emitted from tobacco smoke and generated from malfunctioning fuel burning stoves (wood, kerosene, natural gas, propane) and fuel burning heating systems (wood, oil, natural gas) and from blocked flues connected to these appliances.[26] In developed countries the main sources of indoor CO emission come from cooking and heating devices that burn fossil fuels and are faulty, incorrectly installed or poorly maintained.[27] Appliance malfunction may be due to faulty installation or lack of maintenance and proper use.[26] In low- and middle-income countries the most common sources of CO in homes are burning biomass fuels and cigarette smoke.[27]

Health effects of CO poisoning may be acute or chronic and can occur unintentionally or intentionally (self-harm). By depriving the brain of oxygen, acute exposure to carbon monoxide may have effects on the neurological system (headache, nausea, dizziness, alteration in consciousness and subjective weakness), the cardiovascular and respiratory systems (myocardial infarction, shortness of breath, or rapid breathing, respiratory failure). Acute exposure can also lead to long-term neurological effects such as cognitive and behavioural changes. Severe CO poisoning may lead to unconsciousness, coma and death. Chronic exposure to low concentrations of carbon monoxide may lead to lethargy, headaches, nausea, flu-like symptoms and neuropsychological and cardiovascular issues.[28][26]

The WHO recommended levels of indoor CO exposure in 24 hours is 4 mg/m3.[29] Acute exposure should not exceed 10 mg/m3 in 8 hours, 35 mg/m3 in one hour and 100 mg/m3 in 15 minutes.[27]

Secondhand tobacco smoke

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Secondhand smoke is tobacco smoke which affects people other than the 'active' smoker. It is made up of the exhaled smoke (15%) and mostly of smoke coming from the burning end of the cigarette, known as sidestream smoke (85%).[30]

Secondhand smoke contains more than 7000 chemicals, of which hundreds are harmful to health.[30] Secondhand tobacco smoke includes both a gaseous and a particulate materials which, with particular hazards arising from levels of carbon monoxide and very small particulates (fine particulate matter, especially PM2.5 and PM10) which get into the bronchioles and alveoles in the lung.[31] Inhaling secondhand smoke on multiple occasions can cause asthma, pneumonia, lung cancer, and sudden infant death syndrome, among other conditions.[32]

Thirdhand smoke (THS) refers to chemicals that settle on objects and bodies indoors after smoking. Exposure to thirdhand smoke can happen even after the actual cigarette smoke is not present anymore and affect those entering the indoor environment much later. Toxic substances of THS can react with other chemicals in the air and produce new toxic chemicals that are otherwise not present in cigarettes.[33]

The only certain method to improve indoor air quality as regards secondhand smoke is to eliminate smoking indoors.[34] Indoor e-cigarette use also increases home particulate matter concentrations.[35]

Particulates

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Atmospheric particulate matter, also known as particulates, can be found indoors and can affect the health of occupants. Indoor particulate matter can come from different indoor sources or be created as secondary aerosols through indoor gas-to-particle reactions. They can also be outdoor particles that enter indoors. These indoor particles vary widely in size, ranging from nanomet (nanoparticles/ultrafine particles emitted from combustion sources) to micromet (resuspensed dust).[36] Particulate matter can also be produced through cooking activities. Frying produces higher concentrations than boiling or grilling and cooking meat produces higher concentrations than cooking vegetables.[37] Preparing a Thanksgiving dinner can produce very high concentrations of particulate matter, exceeding 300 μg/m3.[38]

Particulates can penetrate deep into the lungs and brain from blood streams, causing health problems such as heart disease, lung disease, cancer and preterm birth.[39]

Generated from building materials, furnishing and consumer products

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Volatile organic compounds

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Volatile organic compounds (VOCs) include a variety of chemicals, some of which may have short- and long-term adverse health effects. There are numerous sources of VOCs indoors, which means that their concentrations are consistently higher indoors (up to ten times higher) than outdoors.[40] Some VOCs are emitted directly indoors, and some are formed through the subsequent chemical reactions that can occur in the gas-phase, or on surfaces.[41][42] VOCs presenting health hazards include benzene, formaldehyde, tetrachloroethylene and trichloroethylene.[43]

VOCs are emitted by thousands of indoor products. Examples include: paints, varnishes, waxes and lacquers, paint strippers, cleaning and personal care products, pesticides, building materials and furnishings, office equipment such as copiers and printers, correction fluids and carbonless copy paper, graphics and craft materials including glues and adhesives, permanent markers, and photographic solutions.[44] Chlorinated drinking water releases chloroform when hot water is used in the home. Benzene is emitted from fuel stored in attached garages.

Human activities such as cooking and cleaning can also emit VOCs.[45][46] Cooking can release long-chain aldehydes and alkanes when oil is heated and terpenes can be released when spices are prepared and/or cooked.[45] Leaks of natural gas from cooking appliances have been linked to elevated levels of VOCs including benzene in homes in the USA.[47] Cleaning products contain a range of VOCs, including monoterpenes, sesquiterpenes, alcohols and esters. Once released into the air, VOCs can undergo reactions with ozone and hydroxyl radicals to produce other VOCs, such as formaldehyde.[46]

Health effects include eye, nose, and throat irritation; headaches, loss of coordination, nausea; and damage to the liver, kidney, and central nervous system.[48]

Testing emissions from building materials used indoors has become increasingly common for floor coverings, paints, and many other important indoor building materials and finishes.[49] Indoor materials such as gypsum boards or carpet act as VOC 'sinks', by trapping VOC vapors for extended periods of time, and releasing them by outgassing. The VOCs can also undergo transformation at the surface through interaction with ozone.[42] In both cases, these delayed emissions can result in chronic and low-level exposures to VOCs.[50]

Several initiatives aim to reduce indoor air contamination by limiting VOC emissions from products. There are regulations in France and in Germany, and numerous voluntary ecolabels and rating systems containing low VOC emissions criteria such as EMICODE,[51] M1,[52] Blue Angel[53] and Indoor Air Comfort[54] in Europe, as well as California Standard CDPH Section 01350[55] and several others in the US. Due to these initiatives an increasing number of low-emitting products became available to purchase.

At least 18 microbial VOCs (MVOCs) have been characterised[56][57] including 1-octen-3-ol (mushroom alcohol), 3-Methylfuran, 2-pentanol, 2-hexanone, 2-heptanone, 3-octanone, 3-octanol, 2-octen-1-ol, 1-octene, 2-pentanone, 2-nonanone, borneol, geosmin, 1-butanol, 3-methyl-1-butanol, 3-methyl-2-butanol, and thujopsene. The last four are products of Stachybotrys chartarum, which has been linked with sick building syndrome.[56]

Asbestos fibers

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Many common building materials used before 1975 contain asbestos, such as some floor tiles, ceiling tiles, shingles, fireproofing, heating systems, pipe wrap, taping muds, mastics, and other insulation materials. Normally, significant releases of asbestos fiber do not occur unless the building materials are disturbed, such as by cutting, sanding, drilling, or building remodelling. Removal of asbestos-containing materials is not always optimal because the fibers can be spread into the air during the removal process. A management program for intact asbestos-containing materials is often recommended instead.

When asbestos-containing material is damaged or disintegrates, microscopic fibers are dispersed into the air. Inhalation of asbestos fibers over long exposure times is associated with increased incidence of lung cancer, mesothelioma, and asbestosis. The risk of lung cancer from inhaling asbestos fibers is significantly greater for smokers. The symptoms of disease do not usually appear until about 20 to 30 years after the first exposure to asbestos.

Although all asbestos is hazardous, products that are friable, e.g. sprayed coatings and insulation, pose a significantly higher hazard as they are more likely to release fibers to the air.[58]

Microplastics

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Microplastic is a type of airborne particulates and is found to prevail in air.[59][60][61][62] A 2017 study found indoor airborne microfiber concentrations between 1.0 and 60.0 microfibers per cubic meter (33% of which were found to be microplastics).[63] Airborne microplastic dust can be produced during renovation, building, bridge and road reconstruction projects[64] and the use of power tools.[65]

Ozone

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Indoors ozone (O3) is produced by certain high-voltage electric devices (such as air ionizers), and as a by-product of other types of pollution. It appears in lower concentrations indoors than outdoors, usually at 0.2-0.7 of the outdoor concentration.[66] Typically, most ozone is lost to surface reactions indoors, rather than to reactions in air, due to the large surface to volume ratios found indoors.[67]

Outdoor air used for ventilation may have sufficient ozone to react with common indoor pollutants as well as skin oils and other common indoor air chemicals or surfaces. Particular concern is warranted when using "green" cleaning products based on citrus or terpene extracts, because these chemicals react very quickly with ozone to form toxic and irritating chemicals[46] as well as fine and ultrafine particles.[68] Ventilation with outdoor air containing elevated ozone concentrations may complicate remediation attempts.[69]

The WHO standard for ozone concentration is 60 μg/m3 for long-term exposure and 100 μg/m3 as the maximum average over an 8-hour period.[29] The EPA standard for ozone concentration is 0.07 ppm average over an 8-hour period.[70]

Biological agents

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Mold and other allergens

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Occupants in buildings can be exposed to fungal spores, cell fragments, or mycotoxins which can arise from a host of means, but there are two common classes: (a) excess moisture induced growth of mold colonies and (b) natural substances released into the air such as animal dander and plant pollen.[71]

While mold growth is associated with high moisture levels,[72] it is likely to grow when a combination of favorable conditions arises. As well as high moisture levels, these conditions include suitable temperatures, pH and nutrient sources.[73] Mold grows primarily on surfaces, and it reproduces by releasing spores, which can travel and settle in different locations. When these spores experience appropriate conditions, they can germinate and lead to mycelium growth.[74] Different mold species favor different environmental conditions to germinate and grow, some being more hydrophilic (growing at higher levels of relative humidity) and other more xerophilic (growing at levels of relative humidity as low as 75–80%).[74][75]

Mold growth can be inhibited by keeping surfaces at conditions that are further from condensation, with relative humidity levels below 75%. This usually translates to a relative humidity of indoor air below 60%, in agreement with the guidelines for thermal comfort that recommend a relative humidity between 40 and 60 %. Moisture buildup in buildings may arise from water penetrating areas of the building envelope or fabric, from plumbing leaks, rainwater or groundwater penetration, or from condensation due to improper ventilation, insufficient heating or poor thermal quality of the building envelope.[76] Even something as simple as drying clothes indoors on radiators can increase the risk of mold growth, if the humidity produced is not able to escape the building via ventilation.[77]

Mold predominantly affects the airways and lungs. Known effects of mold on health include asthma development and exacerbation,[78] with children and elderly at greater risk of more severe health impacts.[79] Infants in homes with mold have a much greater risk of developing asthma and allergic rhinitis.[80][71] More than half of adult workers in moldy or humid buildings suffer from nasal or sinus symptoms due to mold exposure.[71] Some varieties of mold contain toxic compounds (mycotoxins). However, exposure to hazardous levels of mycotoxin via inhalation is not possible in most cases, as toxins are produced by the fungal body and are not at significant levels in the released spores.

Legionella

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Legionnaires' disease is caused by a waterborne bacterium Legionella that grows best in slow-moving or still, warm water. The primary route of exposure is through the creation of an aerosol effect, most commonly from evaporative cooling towers or showerheads. A common source of Legionella in commercial buildings is from poorly placed or maintained evaporative cooling towers, which often release water in an aerosol which may enter nearby ventilation intakes. Outbreaks in medical facilities and nursing homes, where patients are immuno-suppressed and immuno-weak, are the most commonly reported cases of Legionellosis. More than one case has involved outdoor fountains at public attractions. The presence of Legionella in commercial building water supplies is highly under-reported, as healthy people require heavy exposure to acquire infection.

Legionella testing typically involves collecting water samples and surface swabs from evaporative cooling basins, shower heads, faucets/taps, and other locations where warm water collects. The samples are then cultured and colony forming units (cfu) of Legionella are quantified as cfu/liter.

Legionella is a parasite of protozoans such as amoeba, and thus requires conditions suitable for both organisms. The bacterium forms a biofilm which is resistant to chemical and antimicrobial treatments, including chlorine. Remediation for Legionella outbreaks in commercial buildings vary, but often include very hot water flushes (160 °F (71 °C)), sterilisation of standing water in evaporative cooling basins, replacement of shower heads, and, in some cases, flushes of heavy metal salts. Preventive measures include adjusting normal hot water levels to allow for 120 °F (49 °C) at the tap, evaluating facility design layout, removing faucet aerators, and periodic testing in suspect areas.

Other bacteria

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Airborne bacteria

There are many bacteria of health significance found in indoor air and on indoor surfaces. The role of microbes in the indoor environment is increasingly studied using modern gene-based analysis of environmental samples. Currently, efforts are under way to link microbial ecologists and indoor air scientists to forge new methods for analysis and to better interpret the results.[81]

A large fraction of the bacteria found in indoor air and dust are shed from humans. Among the most important bacteria known to occur in indoor air are Mycobacterium tuberculosis, Staphylococcus aureus, Streptococcus pneumoniae.[citation needed]

Virus

[edit]
Ninth floor layout of the Metropole Hotel in Hong Kong, showing where an outbreak of the severe acute respiratory syndrome (SARS) occurred

Viruses can also be a concern for indoor air quality. During the 2002–2004 SARS outbreak, virus-laden aerosols were found to have seeped into bathrooms from the bathroom floor drains, exacerbated by the draw of bathroom exhaust fans, resulting in the rapid spread of SARS in Amoy Gardens in Hong Kong.[82][83] Elsewhere in Hong Kong, SARS CoV RNA was found on the carpet and in the air intake vents of the Metropole Hotel, which showed that secondary environmental contamination could generate infectious aerosols and resulted in superspreading events.[84]

Carbon dioxide

[edit]

Humans are the main indoor source of carbon dioxide (CO2) in most buildings. Indoor CO2 levels are an indicator of the adequacy of outdoor air ventilation relative to indoor occupant density and metabolic activity.

Indoor CO2 levels above 500 ppm can lead to higher blood pressure and heart rate, and increased peripheral blood circulation.[85] With CO2 concentrations above 1000 ppm cognitive performance might be affected, especially when doing complex tasks, making decision making and problem solving slower but not less accurate.[86][87] However, evidence on the health effects of CO2 at lower concentrations is conflicting and it is difficult to link CO2 to health impacts at exposures below 5000 ppm – reported health outcomes may be due to the presence of human bioeffluents, and other indoor air pollutants related to inadequate ventilation.[88]

Indoor carbon dioxide concentrations can be used to evaluate the quality of a room or a building's ventilation.[89] To eliminate most complaints caused by CO2, the total indoor CO2 level should be reduced to a difference of no greater than 700 ppm above outdoor levels.[90] The National Institute for Occupational Safety and Health (NIOSH) considers that indoor air concentrations of carbon dioxide that exceed 1000 ppm are a marker suggesting inadequate ventilation.[91] The UK standards for schools say that carbon dioxide levels of 800 ppm or lower indicate that the room is well-ventilated.[92] Regulations and standards from around the world show that CO2 levels below 1000 ppm represent good IAQ, between 1000 and 1500 ppm represent moderate IAQ and greater than 1500 ppm represent poor IAQ.[88]

Carbon dioxide concentrations in closed or confined rooms can increase to 1,000 ppm within 45 minutes of enclosure. For example, in a 3.5-by-4-metre (11 ft × 13 ft) sized office, atmospheric carbon dioxide increased from 500 ppm to over 1,000 ppm within 45 minutes of ventilation cessation and closure of windows and doors.[93]

Radon

[edit]

Radon is an invisible, radioactive atomic gas that results from the radioactive decay of radium, which may be found in rock formations beneath buildings or in certain building materials themselves.

Radon is probably the most pervasive serious hazard for indoor air in the United States and Europe. It is a major cause of lung cancer, responsible for 3–14% of cases in countries, leading to tens of thousands of deaths.[94]

Radon gas enters buildings as a soil gas. As it is a heavy gas it will tend to accumulate at the lowest level. Radon may also be introduced into a building through drinking water particularly from bathroom showers. Building materials can be a rare source of radon, but little testing is carried out for stone, rock or tile products brought into building sites; radon accumulation is greatest for well insulated homes.[95] There are simple do-it-yourself kits for radon gas testing, but a licensed professional can also check homes.

The half-life for radon is 3.8 days, indicating that once the source is removed, the hazard will be greatly reduced within a few weeks. Radon mitigation methods include sealing concrete slab floors, basement foundations, water drainage systems, or by increasing ventilation.[96] They are usually cost effective and can greatly reduce or even eliminate the contamination and the associated health risks.[citation needed]

Radon is measured in picocuries per liter of air (pCi/L) or becquerel per cubic meter (Bq m-3). Both are measurements of radioactivity. The World Health Organization (WHO) sets the ideal indoor radon levels at 100 Bq/m-3.[97] In the United States, it is recommend to fix homes with radon levels at or above 4 pCi/L. At the same time it is also recommends that people think about fixing their homes for radon levels between 2 pCi/L and 4 pCi/L.[98] In the United Kingdom the ideal is presence of radon indoors is 100 Bq/m-3. Action needs to be taken in homes with 200 Bq/m−3 or more.[99]

Interactive maps of radon affected areas are available for various regions and countries of the world.[100][101][102]

IAQ and climate change

[edit]

Indoor air quality is linked inextricably to outdoor air quality. The Intergovernmental Panel on Climate Change (IPCC) has varying scenarios that predict how the climate will change in the future.[103] Climate change can affect indoor air quality by increasing the level of outdoor air pollutants such as ozone and particulate matter, for example through emissions from wildfires caused by extreme heat and drought.[104][105] Numerous predictions for how indoor air pollutants will change have been made,[106][107][108][109] and models have attempted to predict how the forecasted IPCC scenarios will vary indoor air quality and indoor comfort parameters such as humidity and temperature.[110]

The net-zero challenge requires significant changes in the performance of both new and retrofitted buildings. However, increased energy efficient housing will trap pollutants inside, whether produced indoors or outdoors, and lead to an increase in human exposure.[111][112]

Indoor air quality standards and monitoring

[edit]

Quality guidelines and standards

[edit]

For occupational exposure, there are standards, which cover a wide range of chemicals, and applied to healthy adults who are exposed over time at workplaces (usually industrial environments).These are published by organisations such as Occupational Safety and Health Administration (OSHA), the National Institute for Occupational Safety and Health (NIOSH), the UK Health and Safety Executive (HSE).

There is no consensus globally about indoor air quality standards, or health-based guidelines. However, there are regulations from some individual countries and from health organisations. For example, the World Health Organization (WHO) has published health-based global air quality guidelines for the general population that are applicable both to outdoor and indoor air,[29] as well as the WHO IAQ guidelines for selected compounds,[113] whereas the UK Health Security Agency published IAQ guidelines for selected VOCs.[114] The Scientific and Technical Committee (STC34) of the International Society of Indoor Air Quality and Climate (ISIAQ) created an open database that collects indoor environmental quality guidelines worldwide.[115] The database is focused on indoor air quality (IAQ), but is currently extended to include standards, regulations, and guidelines related to ventilation, comfort, acoustics, and lighting.[116][117]

Real-time monitoring

[edit]

Since indoor air pollutants can adversely affect human health, it is important to have real-time indoor air quality assessment/monitoring system that can help not only in the improvement of indoor air quality but also help in detection of leaks, spills in a work environment and boost energy efficiency of buildings by providing real-time feedback to the heating, ventilation, and air conditioning (HVAC) system(s).[118] Additionally, there have been enough studies that highlight the correlation between poor indoor air quality and loss of performance and productivity of workers in an office setting.[119]  

Combining the Internet of Things (IoT) technology with real-time IAQ monitoring systems has  tremendously gained momentum and popularity as interventions can be done based on the real-time sensor data and thus help in the IAQ improvement.[120]   

Improvement measures

[edit]

Indoor air quality can be addressed, achieved or maintained during the design of new buildings or as mitigating measures in existing buildings. A hierarchy of measures has been proposed by the Institute of Air Quality Management. It emphasises removing pollutant sources, reducing emissions from any remaining sources, disrupting pathways between sources and the people exposed, protecting people from exposure to pollutants, and removing people from areas with poor air quality.[121]

A report assisted by the Institute for Occupational Safety and Health of the German Social Accident Insurance can support in the systematic investigation of individual health problems arising at indoor workplaces, and in the identification of practical solutions.[122]

Source control

[edit]

HVAC design

[edit]

Environmentally sustainable design concepts include aspects of commercial and residential heating, ventilation and air-conditioning (HVAC) technologies. Among several considerations, one of the topics attended to is the issue of indoor air quality throughout the design and construction stages of a building's life.[citation needed]

One technique to reduce energy consumption while maintaining adequate air quality, is demand-controlled ventilation. Instead of setting throughput at a fixed air replacement rate, carbon dioxide sensors are used to control the rate dynamically, based on the emissions of actual building occupants.[citation needed]

One way of quantitatively ensuring the health of indoor air is by the frequency of effective turnover of interior air by replacement with outside air. In the UK, for example, classrooms are required to have 2.5 outdoor air changes per hour. In halls, gym, dining, and physiotherapy spaces, the ventilation should be sufficient to limit carbon dioxide to 1,500 ppm. In the US, ventilation in classrooms is based on the amount of outdoor air per occupant plus the amount of outdoor air per unit of floor area, not air changes per hour. Since carbon dioxide indoors comes from occupants and outdoor air, the adequacy of ventilation per occupant is indicated by the concentration indoors minus the concentration outdoors. The value of 615 ppm above the outdoor concentration indicates approximately 15 cubic feet per minute of outdoor air per adult occupant doing sedentary office work where outdoor air contains over 400 ppm[123] (global average as of 2023). In classrooms, the requirements in the ASHRAE standard 62.1, Ventilation for Acceptable Indoor Air Quality, would typically result in about 3 air changes per hour, depending on the occupant density. As the occupants are not the only source of pollutants, outdoor air ventilation may need to be higher when unusual or strong sources of pollution exist indoors.

When outdoor air is polluted, bringing in more outdoor air can actually worsen the overall quality of the indoor air and exacerbate some occupant symptoms related to outdoor air pollution. Generally, outdoor country air is better than indoor city air.[citation needed]

The use of air filters can trap some of the air pollutants. Portable room air cleaners with HEPA filters can be used if ventilation is poor or outside air has high level of PM 2.5.[122] Air filters are used to reduce the amount of dust that reaches the wet coils.[citation needed] Dust can serve as food to grow molds on the wet coils and ducts and can reduce the efficiency of the coils.[citation needed]

The use of trickle vents on windows is also valuable to maintain constant ventilation. They can help prevent mold and allergen build up in the home or workplace. They can also reduce the spread of some respiratory infections.[124]

Moisture management and humidity control requires operating HVAC systems as designed. Moisture management and humidity control may conflict with efforts to conserve energy. For example, moisture management and humidity control requires systems to be set to supply make-up air at lower temperatures (design levels), instead of the higher temperatures sometimes used to conserve energy in cooling-dominated climate conditions. However, for most of the US and many parts of Europe and Japan, during the majority of hours of the year, outdoor air temperatures are cool enough that the air does not need further cooling to provide thermal comfort indoors.[citation needed] However, high humidity outdoors creates the need for careful attention to humidity levels indoors. High humidity give rise to mold growth and moisture indoors is associated with a higher prevalence of occupant respiratory problems.[citation needed]

The "dew point temperature" is an absolute measure of the moisture in air. Some facilities are being designed with dew points in the lower 50s °F, and some in the upper and lower 40s °F.[citation needed] Some facilities are being designed using desiccant wheels with gas-fired heaters to dry out the wheel enough to get the required dew points.[citation needed] On those systems, after the moisture is removed from the make-up air, a cooling coil is used to lower the temperature to the desired level.[citation needed]

Commercial buildings, and sometimes residential, are often kept under slightly positive air pressure relative to the outdoors to reduce infiltration. Limiting infiltration helps with moisture management and humidity control.

Dilution of indoor pollutants with outdoor air is effective to the extent that outdoor air is free of harmful pollutants. Ozone in outdoor air occurs indoors at reduced concentrations because ozone is highly reactive with many chemicals found indoors. The products of the reactions between ozone and many common indoor pollutants include organic compounds that may be more odorous, irritating, or toxic than those from which they are formed. These products of ozone chemistry include formaldehyde, higher molecular weight aldehydes, acidic aerosols, and fine and ultrafine particles, among others. The higher the outdoor ventilation rate, the higher the indoor ozone concentration and the more likely the reactions will occur, but even at low levels, the reactions will take place. This suggests that ozone should be removed from ventilation air, especially in areas where outdoor ozone levels are frequently high.

Effect of indoor plants

[edit]
Spider plants (Chlorophytum comosum) absorb some airborne contaminants.

Houseplants together with the medium in which they are grown can reduce components of indoor air pollution, particularly volatile organic compounds (VOC) such as benzene, toluene, and xylene. Plants remove CO2 and release oxygen and water, although the quantitative impact for house plants is small. The interest in using potted plants for removing VOCs was sparked by a 1989 NASA study conducted in sealed chambers designed to replicate the environment on space stations. However, these results suffered from poor replication[125] and are not applicable to typical buildings, where outdoor-to-indoor air exchange already removes VOCs at a rate that could only be matched by the placement of 10–1000 plants/m2 of a building's floor space.[126]

Plants also appear to reduce airborne microbes and molds, and to increase humidity.[127] However, the increased humidity can itself lead to increased levels of mold and even VOCs.[128]

Since extremely high humidity is associated with increased mold growth, allergic responses, and respiratory responses, the presence of additional moisture from houseplants may not be desirable in all indoor settings if watering is done inappropriately.[129]

Institutional programs

[edit]
EPA graphic about asthma triggers

The topic of IAQ has become popular due to the greater awareness of health problems caused by mold and triggers to asthma and allergies.

In the US, the Environmental Protection Agency (EPA) has developed an "IAQ Tools for Schools" program to help improve the indoor environmental conditions in educational institutions. The National Institute for Occupational Safety and Health conducts Health Hazard Evaluations (HHEs) in workplaces at the request of employees, authorized representative of employees, or employers, to determine whether any substance normally found in the place of employment has potentially toxic effects, including indoor air quality.[130]

A variety of scientists work in the field of indoor air quality, including chemists, physicists, mechanical engineers, biologists, bacteriologists, epidemiologists, and computer scientists. Some of these professionals are certified by organizations such as the American Industrial Hygiene Association, the American Indoor Air Quality Council and the Indoor Environmental Air Quality Council.

In the UK, under the Department for Environment Food and Rural Affairs, the Air Quality Expert Group considers current knowledge on indoor air quality and provides advice to government and devolved administration ministers.[131]

At the international level, the International Society of Indoor Air Quality and Climate (ISIAQ), formed in 1991, organizes two major conferences, the Indoor Air and the Healthy Buildings series.[132]

See also

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Sources

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Monographs
Articles, radio segments, web pages

Further reading

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Diagram of a HEPA (high-efficiency particulate air) filter
Reusable washable HVAC air filter

A particulate air filter is a device composed of fibrous, or porous materials which removes particulates such as smoke, dust, pollen, mold, viruses and bacteria from the air. Filters containing an adsorbent or catalyst such as charcoal (carbon) may also remove odors and gaseous pollutants such as volatile organic compounds or ozone.[1] Air filters are used in applications where air quality is important, notably in building ventilation systems and in engines.

Some buildings, as well as aircraft and other human-made environments (e.g., satellites, and Space Shuttles) use foam, pleated paper, or spun fiberglass filter elements. Another method, air ionizers, use fibers or elements with a static electric charge, which attract dust particles. The air intakes of internal combustion engines and air compressors tend to use either paper, foam, or cotton filters. Oil bath filters have fallen out of favour aside from niche uses. The technology of air intake filters of gas turbines has improved significantly in recent years, due to improvements in the aerodynamics and fluid dynamics of the air-compressor part of the gas turbines.

Do-it-yourself air cleaner are low-cost alternative to commercial portable air cleaners.[2]

HEPA filters

[edit]

High efficiency particulate arrester (HEPA),[3][4] originally called high-efficiency particulate absorber but also sometimes called high-efficiency particulate arresting or high-efficiency particulate arrestance, is a type of air filter. Filters meeting the HEPA standard have many applications, including use in clean rooms for IC fabrication, medical facilities, automobiles, aircraft and homes. The filter must satisfy certain standards of efficiency such as those set by the United States Department of Energy (DOE).

Varying standards define what qualifies as a HEPA filter. The two most common standards require that an air filter must remove (from the air that passes through) 99.95% (European Standard)[5] or 99.97% (ASME standard)[6] of particles that have a size greater than or equal to 0.3 μm.

Automotive cabin air filters

[edit]

The cabin air filter, also known in the United Kingdom as a pollen filter, is typically a pleated-paper filter that is placed in the outside-air intake for the vehicle's passenger compartment. Some of these filters are rectangular and similar in shape to the engine air filter. Others are uniquely shaped to fit the available space of particular vehicles' outside-air intakes.

The first automaker to include a disposable filter to keep the ventilation system clean was the Nash Motors "Weather Eye", introduced in 1940.[7]

A reusable heater core filter was available as an optional accessory on Studebaker models beginning in 1959, including Studebaker Lark automobiles (1959-1966), Studebaker Gran Turismo Hawk automobiles (1962-1964) and Studebaker Champ trucks (1960-1964). The filter was an aluminum frame containing an aluminum mesh and was located directly above the heater core. The filter was removed and installed from the engine compartment through a slot in the firewall. A long, thin rubber seal plugged the slot when the filter was installed. The filter could be vacuumed and washed prior to installation.

Clogged or dirty cabin air filters can significantly reduce airflow from the cabin vents, as well as introduce allergens into the cabin air stream. Since the cabin air temperature depends upon the flow rate of the air passing through the heater core, the evaporator, or both, clogged filters can greatly reduce the effectiveness and performance of the vehicle's air conditioning and heating systems.[8]

Some cabin air filters perform poorly, and some cabin air filter manufacturers do not print a minimum efficiency reporting value (MERV) filter rating on their cabin air filters.[citation needed]

Internal combustion engine air filters

[edit]
Used auto engine air filter, clean side
Used auto engine air filter, dirty side
Auto engine air filter clogged with dust and grime
Low-temperature oxidation catalyst used to convert carbon monoxide to less toxic carbon dioxide at room temperature. It can also remove formaldehyde from the air.

The combustion air filter prevents abrasive particulate matter from entering the engine's cylinders, where it would cause mechanical wear and oil contamination.

Most fuel injected vehicles use a pleated paper filter element in the form of a flat panel. This filter is usually placed inside a plastic box connected to the throttle body with duct work. Older vehicles that use carburetors or throttle body fuel injection typically use a cylindrical air filter, usually between 100 millimetres (4 in) and 400 millimetres (16 in) in diameter. This is positioned above or beside the carburetor or throttle body, usually in a metal or plastic container which may incorporate ducting to provide cool and/or warm inlet air, and secured with a metal or plastic lid. The overall unit (filter and housing together) is called the air cleaner.

Paper

[edit]

Pleated paper filter elements are the nearly exclusive choice for automobile engine air cleaners, because they are efficient, easy to service, and cost-effective. The "paper" term is somewhat misleading, as the filter media are considerably different from papers used for writing or packaging, etc. There is a persistent belief among tuners, fomented by advertising for aftermarket non-paper replacement filters, that paper filters flow poorly and thus restrict engine performance. In fact, as long as a pleated-paper filter is sized appropriately for the airflow volumes encountered in a particular application, such filters present only trivial restriction to flow until the filter has become significantly clogged with dirt. Construction equipment engines also use this. The reason is that the paper is bent in zig-zag shape, and the total area of the paper is very large, in the range of 50 times of the air opening.[citation needed]

Foam

[edit]

Oil-wetted polyurethane foam elements are used in some aftermarket replacement automobile air filters. Foam was in the past widely used in air cleaners on small engines on lawnmowers and other power equipment, but automotive-type paper filter elements have largely supplanted oil-wetted foam in these applications. Foam filters are still commonly used on air compressors for air tools up to 5 horsepower (3.7 kW). Depending on the grade and thickness of foam employed, an oil-wetted foam filter element can offer minimal airflow restriction or very high dirt capacity, the latter property making foam filters a popular choice in off-road rallying and other motorsport applications where high levels of dust will be encountered. Due to the way dust is captured on foam filters, large amounts may be trapped without measurable change in airflow restriction.[citation needed]

Cotton

[edit]

Oiled cotton gauze is employed in a growing number of aftermarket automotive air filters marketed as high-performance items. In the past, cotton gauze saw limited use in original-equipment automotive air filters. However, since the introduction of the Abarth SS versions, the Fiat subsidiary supplies cotton gauze air filters as OE filters.

Stainless steel

[edit]

Stainless steel mesh is another example of medium which allow more air to pass through. Stainless steel mesh comes with different mesh counts, offering different filtration standards. In an extreme modified engine lacking in space for a cone based air filter, some will opt to install a simple stainless steel mesh over the turbo to ensure no particles enter the engine via the turbo.

Oil bath

[edit]

An oil bath air cleaner consists of a sump containing a pool of oil, and an insert which is filled with fiber, mesh, foam, or another coarse filter media. The cleaner removes particles by adhering them to the oil-soaked filter media rather than traditional filtration, the openings in the filter media are much larger than the particles that are to be filtered. When the cleaner is assembled, the media-containing body of the insert sits a short distance above the surface of the oil pool. The rim of the insert overlaps the rim of the sump. This arrangement forms a labyrinthine path through which the air must travel in a series of U-turns: up through the gap between the rims of the insert and the sump, down through the gap between the outer wall of the insert and the inner wall of the sump, and up through the filter media in the body of the insert. This U-turn takes the air at high velocity across the surface of the oil pool. Larger and heavier dust and dirt particles in the air cannot make the turn due to their inertia, so they fall into the oil and settle to the bottom of the base bowl. Lighter and smaller particles stick to the filtration media in the insert, which is wetted by oil droplets aspirated there into by normal airflow. The constant aspiration of oil onto the filter media slowly carries most of the finer trapped particles downward and the oil drips back into the reservoir where the particles accumulate.

Oil bath air cleaners were very widely used in automotive and small engine applications until the widespread industry adoption of the paper filter in the early 1960s. Such cleaners are still used in off-road equipment where very high levels of dust are encountered, for oil bath air cleaners can sequester a great deal of dirt relative to their overall size without loss of filtration efficiency or airflow. However, the liquid oil makes cleaning and servicing such air cleaners messy and inconvenient, they must be relatively large to avoid excessive restriction at high airflow rates, and they tend to increase exhaust emissions of unburned hydrocarbons due to oil aspiration when used on spark-ignition engines.[citation needed]

Water bath

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In the early 20th century (about 1900 to 1930), water bath air cleaners were used in some applications (cars, trucks, tractors, and portable and stationary engines). They worked on roughly the same principles as oil bath air cleaners. For example, the original Fordson tractor had a water bath air cleaner. By the 1940s, oil bath designs had displaced water bath designs because of better filtering performance. [9]

Bulk solids handling filters

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Bulk solids handling involves the transport of solids (mechanical transport, pneumatic transport) which may be in a powder form. Many industries are handling bulk solids (mining industries, chemical industries, food industries) which requires the treatment of air streams escaping the process so that fine particles are not emitted, for regulatory reasons or economical reasons (loss of materials). As a consequence, air filters are positioned at many places in the process, especially at the reception of pneumatic conveying lines[10] where the quantity of air is important and the load in fine particle quite important. Filters can also be placed at any point of air exchange in the process to avoid that pollutants enter the process, which is particularly true in pharmaceuticals and food industries. The physical phenomena involved in catching particles with a filter are mainly inertial and diffusional[11]

Filter classes

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Under European normalization standards EN 779, the following filter classes were recognized:

Usage Class Performance Performance test Particulate size
approaching 100% retention
Test Standard
Coarse filters

(used as

Primary)

G1 65% Average value >5 μm BS EN779
G2 65–80% Average value >5 μm BS EN779
G3 80–90% Average value >5 μm BS EN779
G4 90%– Average value >5 μm BS EN779
Fine filters

(used as

Secondary)

M5 40–60% Average value >5 μm BS EN779
M6 60–80% Average value >2 μm BS EN779
F7 80–90% Average value >2 μm BS EN779
F8 90–95% Average value >1 μm BS EN779
F9 95%– Average value >1 μm BS EN779
Semi HEPA E10 85% Minimum value >1 μm BS EN1822
E11 95% Minimum value >0.5 μm BS EN1822
E12 99.5% Minimum value >0.5 μm BS EN1822
HEPA H13 99.95% Minimum value >0.3 μm BS EN1822
H14 99.995% Minimum value >0.3 μm BS EN1822
ULPA U15 99.9995% Minimum value >0.3 μm BS EN1822
U16 99.99995% Minimum value >0.3 μm BS EN1822
U17 99.999995% Minimum value >0.3 μm BS EN1822

European standard EN 779, on which the above table is based, remained in effect from 2012 to mid-2018, when it was replaced by ISO 16890.[12]

See also

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References

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  1. ^ "California Environmental Protection Agency - Air Cleaning Devices for the Home, Frequently Asked Questions" (PDF). California Environmental Protection Agency Air Resources Board. Retrieved 2016-12-14.
  2. ^ Holder, Amara L.; Halliday, Hannah S.; Virtaranta, Larry (2022). "Impact of do-it-yourself air cleaner design on the reduction of simulated wildfire smoke in a controlled chamber environment". Indoor Air. 32 (11): e13163. doi:10.1111/ina.13163. ISSN 1600-0668. PMC 9828579. PMID 36437679.
  3. ^ HEPA Company glossary of terms
  4. ^ Originally High Efficiency Particulate Arrestment - see thefreedictionary.com
  5. ^ European Standard EN 1822-1:2009, "High efficiency air filters (EPA, HEPA and ULPA)", 2009
  6. ^ American Society of Mechanical Engineers, ASME AG-1a–2004, "Addenda to ASME AG-1–2003 Code on Nuclear Air and Gas Treatment", 2004
  7. ^ Vwlarry (19 May 2009). "Nils Wahlberg and Nash - Salute To A Great Engineer And Unsung Automobiles".
  8. ^ "Dirty cabin air filter symptoms". FIRST BRANDS GROUP LLC. Retrieved 12 June 2024.
  9. ^ Peter, Paul. "Isolier Konzept". Retrieved 26 September 2022.
  10. ^ "Air filtration - Dust collectors".
  11. ^ "Solid Gas separation (cyclone - filtration)".
  12. ^ ISO 16890-1:2016(en) Air filters for general ventilation — Part 1: Technical specifications, requirements and classification system based upon particulate matter efficiency (ePM)
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Frequently Asked Questions

Common signs include unusual noises like rattling or banging, decreased cooling efficiency, and vibrations when the unit is running. These symptoms suggest components such as screws, bolts, or internal elements like fan blades might be loose.
First, turn off and unplug the air conditioner to ensure safety. Remove the cover following your units manual instructions. Inspect visible components such as screws, panels, and fan blades for looseness. Use appropriate tools to gently tighten any loose screws or connections without overtightening.
If you hear persistent unusual noises despite tightening visible components, observe significant performance issues after inspection, or feel unsure about handling electrical elements safely, its best to call a professional HVAC technician. They can perform a thorough inspection and address complex issues beyond basic DIY fixes.