Air pollution was the 4th leading risk factor for early death worldwide in 2019, surpassed only by high blood pressure, tobacco use, and poor diet. It was the leading risk factor for premature deaths in India in 2019, accounting for nearly 18% of all deaths – 1.67 million deaths due to air pollution in India in 2019.
Important Reasons to have an Air purifier
Indoor air pollution is ranked among the top 5 environmental health risks to the public by Environmental Protection Agency. Carbon-based gaseous pollutants (VOCs) could be 2 – 5 times higher than outdoors. In India, Indoor air pollution is one of the top 10 disease risk factors. It is invisible but no less a threat to our health. A large part of household items in our homes as well offices are sources of Indoor Air Pollution.
What should be looked at when buying a good air purifier?
- Clean Air Delivery Rate (CADR) at a medium speed, where the noise level is acceptable and not high – it should be able to provide for atleast 2 air changes in one hour.
- HEPA filter quality: A good quality HEPA filter is an important factor to consider. A true HEPA filter should be of H12 or H13 grade.
- Carbon filter: A good quality carbon filter weighing 500 grams or above.
- Pre-filter: a good washable pre-filter to take care of larger particles.
- Noise levels: Below 50 dB, at medium speed, should be acceptable.
- Indicator for a filter change.
Air purifiers have two broad categories – passive filtration and active filtration
The air purifier should only absorb harmful and gaseous pollutants and not microbiological pollutants. It is fine to breathe in a small number of microbiological pollutants. We need to breathe in a certain amount of them so our bodies can battle them. If they are completely removed, that is, we stay in a completely sterile environment, we lose our immunity against them.
How do various types air purifiers work?
- HEPA Technology
- Activated Carbon Technology
- UV Technology
- Negative Ion
- HEPA air purifiers are the most effective at trapping airborne particles; however, they do not remove odours, chemicals or gases.
- Carbon filters are used to remove odours & gases. They combat Volatile Organic Compounds (VOCs), like formaldehyde. These are hazardous gases that normally pass through a HEPA. Activated carbon filters react with these hazardous gases to remove them from the air.
- UV technology air purifiers have a UV lamp installed and as microorganisms pass by the UV rays radiated from the lamp, microorganisms such as bacteria and viruses are destroyed. The challenge is to remove ozone which most of the cheaper purifiers are not able to do.
- Negative ion air purifiers use chemical injections to clean the air. They merely mask the polluted air as opposed to cleaning it. The negative ion simply takes the airborne particles out of the air and transfers them to walls and surrounding solid items in the room instead of eliminating them. When they are stuck to walls and other surfaces, they have the ability to become loose and re-circulate themselves back into the air again causing air pollution.
- Ozone air purifiers are very similar to negative ion purifiers, except that , they emit ozone into the air. While these air purifiers will force the heavier particles to the ground, these products are not right for everyone. Exposure to ozone may ignite asthma symptoms and a high enough level can even damage the lungs.
The Fact Card
Any air purifier with an ozonizer, negative ionizer, UV light, or any kind of ‘active filtration’ technology has the potential to emit ozone or other harmful by-products. In India, we already have high levels of ozone in the air in most parts of India. A small amount of additional ozone to an already high level will make the pollution problem worse having serious harmful effects on human health. Hence, any air purifier that can possibly emit ozone or any by-product should be avoided.
The bad news about air purifiers
Air purifiers, especially the ones using active particulate filtrations, are not best for your lungs. Most of the present air purifiers release ozone as a by-product. Except for air purifiers with passive filtration technology, most of the available air purifiers are either an ozonizer, releasing ozone, or an ionizer, releasing electric charge in the air that results in ozone. These machines are banned in the US and many other developed countries, but not in India.
Reference links used:
1. – https://en.wikipedia.org/wiki/Air_purifier
2. – https://ehs.umass.edu/air-purifiers-fact-sheet
3. – https://joplins.net/articles/understanding-5-types-air-cleaners-purifiers
4. – How to grow fresh air (Kamal Meattle & BarunAggarwal)
5. – https://learn.allergyandair.com/types-of-air-purifiers/