Air purifiers – HEPA system

In India, air pollution in cities is a major public health concern. Most of the time the levels are reported to be 3 o 4 times higher than the permissible limits. The situation is very grave.

Refer today’s TOI news on air purifiers.

Generally, pollution in the air is made up of a lot of gaseous chemicals -oxides of nitrogen sulphur and carbon, trace elements, some of them are toxic or carcinogenic. There are particulate matter of different sizes (PM₁₀, PM_2.5) there are chemicals, Greenhouse gases (CO₂) vehicular exhausts-mostly organics, smoke particulates, heavy metals etc, etc. The concentration of the pollution in air varies from place to place depending on the location of sources of the pollution, wind velocity and wind direction.

It should be borne in mind that there is no single filter which can remove all these pollutants from the air. High Efficiency Particulate Air (HEPA) Filters are available in the market today to remove about 99% of the particulates of sub-micron size. The so-called advertised HEPA air purifiers are expensive and available for use at home. There are many brands coming in the market. Consumers will be taken for a ride by the advertisements and marketing strategy.

As a consumer, one should ask the following questions:

1.   HEPA is a particulate filter. How it is going the remove gaseous and organic pollutants?

2.    The filter is highly efficient. Due to high dust load, the filter is going get choked within a few days. Replacement of the filters will be very expensive.

3.     In a practical sense, one has to close all windows and doors in rooms, put on AC and then use the HEPA filtration system. Is it practical?

4.     What will be the operational cost per month for say 4 hours a day use?

5.     What happens when the person goes out for daily walk or travel in a car or bus? He will be exposed to the same polluted air outside.

6.  Health issues will be more when you expose your biological systems to very clean air inside a room and highly polluted air outside routinely.

The only way to solve this problem is to reduce the pollution levels below the permissible levels. Every one of us should focus on reducing pollution at the source rather than spending hard-earned money on such air purifiers.