Air Purifiers in Delhi: Expert Explains Limitations and True Protection

As Delhi-NCR grapples with severe air pollution, senior pulmonologist Dr G.C. Khilnani, a member of the WHO expert committee on global air pollution and health, warns against over-reliance on air purifiers.

He states that even low readings on purifiers do not signify completely safe air, as most standard devices primarily trap particulate matter but fail to block hazardous gases like carbon monoxide, nitrogen oxides, sulphur dioxide, and ultrafine nanoparticles.

Dr Khilnani emphasises that air purifiers can offer some benefit, particularly for vulnerable individuals such as those with chronic lung or heart disease and the elderly, but only under stringent conditions.

These include ensuring the purifier is correctly sized for a consistently closed room, equipped with HEPA and activated carbon filters, and operated continuously with regular filter replacements. Poor maintenance risks reduced effectiveness and even ozone generation. For daily commuters, relying solely on purifiers creates an "illusion of safety."

The most effective protection, according to Dr Khilnani, involves limiting outdoor activity, especially during peak smog hours in early mornings, and consistently using N95 or N99 masks. Cloth or surgical masks provide minimal protection against toxic air.