Air Conditioners: Filtering Pollution Or Just Cool Air?

Air conditioners are widely recognised for their ability to regulate temperature and provide comfort and convenience, but there is a common misconception about their capacity to clean indoor air. While some air conditioners may have built-in filters that can help improve indoor air quality, their primary function is to cool the air, not to purify it. This distinction is important, as it affects consumers' expectations of the air they breathe and their health.

Air conditioners recycle indoor air

Air conditioners do not bring in fresh air from outside. Instead, they recycle indoor air. This is because cooling outside air takes more energy than cooling indoor air. Recirculating indoor air is more energy-efficient and is the primary mode for most air conditioners.

The process of air conditioning involves moving heat, not air, from inside to outside. Air conditioners use refrigerants and their special properties to absorb the heat inside a house and expel it outside. The refrigerant gets cold inside the house by taking the heat from the air, and then the warm refrigerant moves outside, where a fan rejects the heat to the outside.

The fans in an air conditioning unit draw warm air in through a vent and blow it over the evaporator coil, which is filled with refrigerant to remove heat from the warm air. This process cools the air but does not actively improve indoor air quality. In fact, air conditioning can worsen indoor air quality by circulating stale and polluted indoor air. It is common to close all windows and doors when the air conditioning is on, which further traps indoor contaminants.

Additionally, air conditioners do not purify the air. While there is an air filter located near the return air duct or air handler that can filter dust, pollen, and other allergens, this is not a part of the air conditioner itself but rather a part of the entire HVAC system. To improve indoor air quality, it is recommended to open windows when the air outside is a desirable temperature or to install a Heat Recovery Ventilation (HRV) system, which pre-cools or pre-heats the outside air being brought in.

Air conditioners do not inherently purify the air

Air conditioners are designed to regulate temperature, not to purify the air. While some air conditioners may have built-in filters that can help improve indoor air quality, they are primarily designed to capture larger particles such as dust, pet hair, and pollen. These filters are not sufficient to filter out smaller pollutants, such as bacteria and viruses, which are critical in air purification. Therefore, while air conditioners provide comfort and convenience, they should not be relied upon as a means of air purification.

The primary function of an air conditioner is to create a cool, controlled atmosphere that enhances the comfort and livability of indoor spaces. It achieves this by circulating already present indoor air. This means that stale and polluted air is circulated, which can worsen indoor air quality, especially when windows and doors are closed during its operation. The main purpose of an air conditioner is not to actively improve indoor air quality but to provide temperature-regulated air for comfort.

While air conditioners do filter out some debris and larger particles, they are not designed as air purification systems. Air purifiers, on the other hand, are specifically engineered to cleanse the air by filtering pollutants and contaminants. They are more effective at removing finer particles, virus particles, bacteria, and other polluted air particles. For individuals focused on achieving pristine indoor air quality, the use of specialised air purifiers or advanced filtration systems is recommended in conjunction with an HVAC setup.

It is important to note that the presence of air filters in some air conditioners does not make them air purifiers. These filters are often included to safeguard the internal components of the AC unit from larger particles. To ensure optimal performance and maintain indoor air quality, regular maintenance of air conditioners is crucial. This includes cleaning or replacing the dust filters every one to three months to prevent airborne pollutants from circulating and causing strain on the cooling system.

In summary, air conditioners do not inherently purify the air. While they may have some filtration capabilities, their primary function is temperature regulation. For those seeking to improve indoor air quality, additional measures such as dedicated air purifiers or advanced filtration systems are necessary to achieve a healthy and pristine indoor air atmosphere.

Air conditioners can filter out large particles

Air conditioners are widely recognised for their ability to provide comfort and convenience. However, there is a common misconception about their capacity to clean indoor air. The primary function of an air conditioner is to regulate temperature, not to purify the air.

Air conditioners are designed to cool indoor air, not purify it. They achieve this by drawing in warm air, removing its heat, and then circulating the cooled air back into the room. This cycle is facilitated by a refrigerant and a compressor, which enables the movement of the refrigerant through the system. While air conditioners do filter out large particles such as dust, pollen, and other allergens, this is incidental to their main purpose of temperature regulation.

The air filters found in some air conditioners are designed to capture larger particles such as dust and pet hair. These filters help to protect the internal components of the AC unit. However, they are not sophisticated enough to filter out smaller pollutants like pollen, bacteria, and viruses, which are critical to consider for effective air purification. Therefore, while air conditioners provide relief from heat, they should not be solely relied upon to purify the air.

For those seeking to improve indoor air quality, additional steps should be taken, such as employing specialised air purifiers, installing more advanced air filters, or incorporating air purification systems into their existing HVAC setup. These measures will help to achieve a healthier and more pristine indoor air atmosphere.

It is also important to note that air conditioners can sometimes worsen indoor air quality. When an air conditioner is not properly maintained or is overused, indoor air quality can decrease. Additionally, it is common practice to close all windows and doors when the air conditioner is running, which further traps indoor contaminants. Therefore, it is crucial to understand that an air conditioner is just one aspect of maintaining good indoor air quality, and other measures such as proper ventilation and regular maintenance should also be prioritised.

Air conditioners do not bring in outdoor air pollution

When an air conditioner is not properly maintained, it can be a hazard to those with allergies and asthma, increasing the frequency and intensity of symptoms and attacks. It is a common misconception that the air filter is a part of the air conditioner itself, when in reality, it is a part of the entire HVAC system. While air filters with a higher MERV rating are better able to filter particles, the air conditioning unit itself does not clean the indoor air.

To test whether your air conditioning system is worsening indoor air quality, you can use a particle counter to test the air coming out of the unit. If you are in Beijing or Delhi, Smart Air provides indoor air quality audits to test your central air system. They also test for general particulate air pollution and gas pollutants.

Air conditioners can also cause air pollution and contribute to global warming. Older air conditioners use chlorofluorocarbon gas, which, when leaked into the atmosphere, damages the ozone layer. Air conditioners also release pollutants such as carbon dioxide, carbon emissions from coal-burning, and nitrogen oxides, which contribute to global warming and can cause respiratory problems.

Air conditioners can worsen indoor air quality

While air conditioners do filter the air, they have important limitations. Air conditioners are designed to improve comfort by cooling the air and regulating temperature. They do so by circulating already present air, which can be stale and polluted. When running an air conditioner, it is common to close all windows and doors, which can save money and allow the air conditioner to run effectively. However, this also traps indoor contaminants, worsening indoor air quality.

Air conditioners recycle indoor air without purifying it, allowing unclean air to circulate indoors and decrease indoor air quality. Air circulation without ventilation can cause symptoms such as nasal issues, itchy eyes, headaches, dizziness, or difficulty breathing. In extreme cases, it can even lead to asthma attacks and pneumonia. The dry cold air produced by air conditioners can also cause skin, eye, and nose dryness, making the skin itchy and flaky.

Additionally, when an air conditioner is not properly maintained or is overused, indoor air quality decreases further. An unmaintained air conditioning unit can be hazardous to those with allergies and asthma, exacerbating symptoms and triggering attacks. Air conditioners can also become breeding grounds for dust mites and mold if not adequately cleaned and maintained. Therefore, routine maintenance is key to ensuring that your air conditioner maintains good indoor air quality.

To improve indoor air quality, it is important to introduce outdoor air through natural ventilation, such as opening windows and doors, or mechanical means, like outdoor air intakes associated with the HVAC system. While air conditioners are not designed to purify the air, additional devices can be used alongside them to improve indoor air quality. Solutions such as a whole-home humidifier, dehumidifier, upgraded air filters, air purifiers, or an indoor air quality monitor can work in conjunction with HVAC systems to enhance indoor air quality.

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