HEPA Air Purifier Side Effects

This article discusses the potential side effects that can occur due to the usage of HEPA filter air purifiers. The various reasons and cases when HEPA filter air purifiers are discussed, and lastly, we talk about the methods which help to minimise and prevent the exacerbation of these side effects.

Can HEPA Air Purifiers have any side effects on human health?

Ideally, HEPA filter air purifiers are designed to ensure that the user does not suffer from poor indoor air quality. However, sometimes the air purifier itself may generate such adverse conditions, which can potentially have side effects on the user’s health.

What are HEPA filter air purifiers and why do you need one?

HEPA stands for High Efficiency Particulate Air  filters. These filters are made out of  borosilicate glass fibers or plastic fibers (e.g., polypropylene) bound together with up to 5% acrylic binder, which is the same compound that binds latex paint to a house.

Over the previous decades, the rise in air pollution has been prevalent, especially in urban areas. Air pollution is caused by both natural processes as well as anthropogenic (i.e., human-based) activities, however, the latter is the main culprit.

Activities related to rapid urbanisation, such as traffic related air pollution, emissions from industries such as thermal power plants, brick kilns, factories, etc., and other such processes have significantly contributed towards the steady degradation of air quality.

An average individual spends more than 90% of their time within an enclosement, with more than 80% of this time in an indoor setting such as offices, residents, and so on.

There have been studies that have shown that in large cities, indoor air pollution poses a higher risk on human health than outdoor air pollution.

Indoor air pollution can originate from indoor sources, such as household items, furniture, combustion of fuels, smoking, and so on.

Indoor air can also get polluted when pollution from outdoors infiltrates through openings such as doors, windows, gaps, cracks, seeps, and so on.

Amongst these pollutants, the worst is particulate matter, or simply PM. PM refers to particles in the sub-micron range that are suspended in the air. 

There are two forms of particulate matter: coarse particulate matter (PM10) and tiny particulate matter (PM2.5). PM2.5 is a prevalent problem among them.

There are many sources of PM in the ambient air. Some of the main sources include factories, power plants, refuse incinerators, fumes from automobiles, construction activities, fires and natural windblown dust.

Indoor sources include burning of  fuels, smoking, and other hobbies, such as woodworking, painting, etc.

Numerous studies have shown that exposure to polluted air containing particulate matter have been shown to cause various issues, such as:

  • premature death in people with heart or lung disease
  • nonfatal heart attacks
  • irregular heartbeat
  • aggravated asthma
  • decreased lung function
  • increased respiratory symptoms, such as irritation of the airways, coughing or difficulty breathing.

Given the variety of PM present, they have various sources. These particles can originate from a variety of sources, which can be indoors, or outdoor pollution that enters through doors, windows, seeps, cracks, and so on.

This is where air purifiers come in the picture. Air purifiers mainly work on particulate matter, and rid the indoor ambient air of the PM pollution in the room, thereby cleaning the indoor air and making it safe for breathing.

They filter out particulate matter less than 0.3 microns, and the HEPA filters typically have an efficiency of more than 99%. For people who suffer from allergies, asthma, or other illnesses, air purifiers can be a lifesaver.

These ingenious gadgets function to remove dust, smoke, pollen, and other noxious pollutants from the air, which may cause discomfort and sickness.

What are some of the side effects of HEPA filter air purifiers?

Although HEPA filter air purifiers are now an essential appliance for most homes, they can also have certain side effects. Some of these include:

  • Cannot filter out VOCs and viruses
  • Cannot get rid of odors
  • Generation of ozone gas
  • Breeding ground for mold and bacteria

We shall discuss these side effects in more detail.

Cannot filter out VOCs and viruses

VOCs is an acronym for volatile organic compounds, which refer to a variety of organic compounds that are emitted from certain materials in the form of a gas. 

These compounds are present in commonly stored household products, such as paints, solvents, cleaning products, cosmetics, and fuels.

All of these products release VOCs when in use, as well as when they are stored. Exposure to VOCs can cause short term health effects such as irritation of the eyes, nose and throat, headaches, and nausea.

Long term exposures can adversely affect the liver, kidneys, and the central nervous system. 

In the current scenario, the covid pandemic has been a prevalent issue. Studies have shown how the virus can spread indoors from infected articles to healthy people. Hence, prevention is necessary.

However, this is where air purifiers fall short. They fail to get rid of VOCs, and cannot catch virus particles, since the typical size of a virus is less than the effective range for the air purifier’s functioning.

Cannot get rid of odors

Odors are usually caused by a wide range of substances that are present as gases in the ambient indoor air. They can be attributed to certain compounds such as the aforementioned VOCs, decaying of organic matter such as food stuff, and so on.

Air purifiers which are purely consisting of HEPA filters are ineffective against these species, as the filter cannot absorb gaseous substances on itself.

Generation of ozone gas

Certain air purifiers use ionisers that generate ions at the rate of thousands per minute, or electric plates that cause the electrostatic deposition of charged pollutants.

However, in their process, they can cause a breakdown of oxygen molecules, which in turn react with each other to form ozone.

Ozone is a highly reactive gaseous molecule which is naturally present in the upper layers of the atmosphere, where it absorbs the sun’s damaging ultraviolet radiation.

When present in the lower levels of the atmosphere, however, it acts as a pollutant, and can have serious adverse effects on human health, which also includes afflictions related to the cardiovascular and respiratory systems.

Ozone acts as an irritant, due to its pungent odor. It can cause wheezing, irritation in the nose and throat, runny nose, watery eyes, difficulty in breathing, and so on.

Additionally, ozone can also worsen the condition of people who are suffering from diseases such as asthma, emphysema, and bronchitis.

Breeding ground for mold and bacteria

For cases where the air purifier is installed in rooms with high relative humidity, one of the common substances to get trapped in the air filter would be mold and bacteria.

If the filter is left on at all times, the amount of water vapour that gets entrapped in the filter will also increase. This provides the optimal dark and humid condition within the filter itself that promotes the growth of mold and bacteria.

Not only will this reduce the efficiency of the filter, it will also serve as a breeding ground for mold and bacteria, which in turn would be propagated through the air purifier.

Ways to prevent and minimise the side effects

HEPA filter air purifiers are meant to make life easy and the air clean for the user. However, we have seen that in some cases, it can have the opposite of the desired result.

However, these issues have solutions which help to minimise or prevent them from happening in the first place. These methods include:

  • Buying purifiers that do not generate ozone
  • Using activated carbon filter
  • Regular maintenance and replacement of HEPA filters.
  • Pairing it with other devices under certain conditions.

We shall discuss the importance of these methods.

Buying purifiers that do not generate ozone

This is a more of a preventive method of dealing with the side effect. There are many commercially available air purifiers which have none to very minimal ozone production. 

Usually, buying an air purifier with a True HEPA filter would be your safest option.

Similarly, one should refrain from investing in an air purifier that contains an ioniser, since they generate a lot of ozone in their working. Furthermore, these purifiers aren’t as efficient as the HEPA filter air purifiers.

Using activated carbon filter

Certain models of HEPA filter air purifiers come with an additional activated carbon filter. These filters are especially effective against gaseous forms of pollutants.

The activated carbon present on these filters absorb the gaseous pollutants passing through them. They are especially effective against VOCs and other forms of gaseous air pollutants as well.

Regular maintenance and replacement of HEPA filters

It is ideal to get your air purifier serviced on a regular basis by the technicians, as it is beneficial for the long run. This is also very helpful since any latent issues could also be identified and dealt with before it becomes a menace.

HEPA filters have a fixed life span till which they can work against pollutants efficiently. However, with time, this efficiency starts to decline, since more and more particles are stuck in the filter media.

Therefore, it is ideal to replace your HEPA filters. Usually, the manufacturing company themself provide the time span in which the HEPA filter should be replaced.

Other FAQs about Air Purifiers and Filters that you may be interested in.

how air purifiers work in cars?

The dangers of Negative ion air purifiers

Can air purifiers remove dust?


This article talks about the various side effects that are caused by HEPA filter air purifiers, which include its inefficiency against odors and virus particles, its tendency to become a breeding ground for mold and bacteria, and in some cases, generate ozone gas.

However, we also discuss how to counteract these side effects, which mainly requires regular maintenance as well as utilising additional components, such as activated carbon filters.


How can I run my air purifier in humid conditions?

In order to run your air purifying device in high humidity settings, it is vital to install a dehumidifier along with the air purifier.

This would help to reduce the humidity levels in the room/house, which in turn would make it easier for the air purifier to run optimally.

Furthermore, low humidity levels created by the dehumidifier would also help to hamper the growth of bacteria and mold within the rooms itself, thereby making the indoor air cleaner.

How to tell if my air purifier is producing ozone?

Although manufacturers usually mention it along with the product, sometimes, due to technical issues, your air purifier might start generating ozone. 

You can tell whether there is ozone by looking out for some of the  most common symptoms such as a feeling of irritation in the eyes, nose and throat. 

Some people may also experience respiratory or heart symptoms such as shortness of breath, chest pain, and wheezing.


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