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Do Air Conditioners Filter the Air?

Air conditioners have the primary function of refreshing an indoor environment. These devices control the room’s internal temperature by recycling hot air and cooling it. At the same time, they can control humidity and even cause a slight air-purifying effect.

Air conditioners can filter the air thanks to the dust filters inside the unit. They help remove some polluting substances, like pollen and dust, as the indoor air passes through them. But when it comes to smaller particles, the air conditioner is not as effective as an air purifier

This article will explain some of the aspects related to the topic, including the most efficient types of filters for your air conditioner and the advantages and disadvantages of these devices compared to air purifiers. 

How Do Air Conditioners Filter the Air?

Air conditioners are designed to produce fresh air and reduce heat in an indoor environment. This happens because they capture the air inside the room and cools it before returning it to the environment.

During the process, impurities from the indoor air are usually sucked into the filters of the air conditioner. With the air being forced through it, the filtering material can quite efficiently remove particles and other contaminants, such as pollen, dust and dirt, fibers, mold spores, hair, and animal fur.

All brands of air conditioners have a dust filter system. The problem is that some materials cannot retain smaller particles; others are not durable and require constant maintenance and cleaning.

However, it is possible to change your air conditioner’s filters and replace them with better ones.

Which Filters Are Most Efficient?

Some air conditioning brands promise several stages of filtration and better quality of recycled air. But you can try to improve the filtration system of your current device just by changing its filters. 

Depending on its material, some types of filters are reusable; others must be replaced frequently. Remember that different filters work for various pollutants and places.

The MERV Classification

The most recommended when choosing the filter is to be based on the MERV classification – which means Minimum Efficiency Reporting Value. It is a measurement scale created in 1987 by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE).

The MERV classification can help you identify the most appropriate filter for a specific situation. Its scale is based on values from 1 to 16. The higher the value, the greater the percentage of particles captured by the filters. 

A MERV 16 rating usually filters more than 95% of particles from indoor air. On average, common home filters range from MERV 8 to MERV 13, with the ability to eliminate between 45% and 75% of the polluting particles, considerably improving the air quality. 

ASHRAE recommends MERV 13 filters but assumes that a value of 14 (or better) is preferred for people with weak immunity, as they retain bacteria, sneeze drops, and microorganisms. 

The Different Materials

According to Rescue Heat & Air, a US company that specializes in repairing and installing air conditioning systems, these are the types of filters available:

Nylon Thread Filters

The nylon thread filters can be found in virtually all models of air conditioners – even when the device uses other filtration systems. It’s composed of a fine mesh of nylon threads that trap impurities as the air passes. The material allows the filter to be removed and cleaned.

Fiberglass Air Filters

Probably the most common model on the market. The fiberglass is superimposed on thick screens; the thicker the screen, the better the filtering power. These filters are disposable, must be changed frequently, and are therefore cheaper, but may not be as efficient in protecting against dust and small particles. 

Electrostatic Air Filters

Mainly used in industrial environments that need pollution control, but recently adapted into a version for home appliances. It works with positively charged surfaces that attract the negative charges of the captured substances, causing the pollutants to stick to the filter walls.

HEPA Filters

HEPA stands for High-Efficiency Particulate Air. Therefore, it’s considered the most efficient filter. Created by the US Army to help with chemical, biological, and radiological filtration processes, it was eventually adapted for household appliances, such as air conditioners and vacuum cleaners.

Unfortunately, due to airflow restrictions, this type of filter cannot normally be installed on residential air conditioners without a professional modification of the whole system. Generally, a device designed for home use doesn’t have enough fan or motor capacity to operate with HEPA filters.

Air Conditioner vs. Air Purifier: How to Choose?

The Air Conditioner Vs Air Purifier dilemma is usually defined by the fact that most people already have some air conditioning device at home. But what are the pros and cons of deciding between air conditioners and air purifiers? 

Here’s a video that explains the basic differences: 

The first aspect is the most obvious: while in air conditioners, air filtration is a bonus. This is the primary objective of air purifiers– to make the air cleaner and healthier. However, unlike air conditioners, purifiers don’t control air temperature or humidity. There are two main types: with HEPA filters and ionizers.

The air purifier with HEPA filters circulates the indoor air through a system that captures and collects airborne pollutants into the filter. The ionizer emits ions that directly affect the air contaminants.

Although the air conditioner manages to purify the air to some extent, this is not its main objective. More effective in filtering, the air purifier is the best option if you have breathing problems or allergies. However, the air purifier simply circulates the room air through a filtration system. It comes out clean but at the same temperature. That is, air conditioning is the best option if you also want to control the temperature and humidity of your home.


Air conditioning units serve mainly to control the internal temperature of an indoor environment, but they also have a medium level of air purification.

They are a good choice for people who suffer from respiratory problems since, in addition to purifying the air they also control humidity.

But the efficiency of air conditioning in cleaning indoor air depends a lot on the choice of filters and the maintenance of the device, which must receive periodic cleaning – or else some of the pollutants concentrated in the filter can make their way back into the air.

Either way, if you want to ensure the best of both worlds, air conditioners and air purifiers can be used in the same room and at the same time: while one will clean the air in the room, the other will cool it and control humidity levels.

There are also some natural and effective ways to help clean the air in your home, such as placing indoor plants in several rooms and regularly airing the house. A clean environment improves your health and quality of life; therefore, it’s not something to be neglected.