Air pollution levels in India have worsened sharply in recent weeks. The Air Quality Index (AQI) in Delhi and the National Capital Region has crossed 428, placing it in the ‘severe’ category. Authorities have already implemented Stage III of the Graded Response Action Plan (GRAP) to curb emissions. However, as outdoor air becomes toxic, many people are turning to air purifiers to maintain clean indoor air.
The sustained exposure to fine particulate matter (PM2.5) is especially harmful. It penetrates deep into the lungs, triggering chronic inflammation and increasing the risk of respiratory diseases. According to the Global Initiative for Chronic Obstructive Lung Disease (GOLD), newer terms such as Pre-COPD, Early COPD, and Young COPD have been introduced to identify those at risk earlier — underscoring how prolonged exposure to polluted air can damage even young, healthy lungs.
Given these conditions, investing in an air purifier is not just a convenience but a health necessity. Here are five key factors to consider before buying one.
1. Match CADR to room size
CADR, or Clean Air Delivery Rate, measures how much filtered air a purifier can supply every hour (in cubic meters per hour). To find a suitable purifier, calculate the area of your room and match it with the purifier’s CADR rating. For instance, a larger room requires a higher CADR. A purifier with an insufficient CADR will take longer to clean the air and may not be effective during severe pollution days.
2. Check the filter type
Don't compromise in this department because, it is after all responsible for the only thing that an air purifiers are designed to do. So, filters are the most important component of an air purifier. A True HEPA (High-Efficiency Particulate Air) H13 filter is essential — it captures 99.97% of airborne particles as small as 0.3 microns, including PM2.5, dust, and pollen. For cities with high pollution levels, an activated carbon filter is also crucial. It absorbs gases, odors, and volatile organic compounds (VOCs) that a HEPA filter cannot trap. The combination of these filters ensures cleaner and safer indoor air.
3. Verify air changes per hour (ACH)
ACH indicates how often an air purifier can clean the entire air volume in a room within an hour. A purifier with at least 2 ACH is adequate for general use. However, during heavy pollution or for people with respiratory sensitivities, a model offering 4 to 5 ACH is recommended. This means the air inside the room is refreshed every 12 to 15 minutes, maintaining a consistent air quality level.
4. Consider noise and energy efficiency
Air purifiers must run continuously for long hours to be effective. Hence, choosing one with low operational noise is important, especially for bedrooms. A noise level below 50 dB at high speed and around 25–30 dB in sleep mode is suitable for most users. Check for Energy Star-rated models to ensure energy efficiency, as purifiers can otherwise consume significant electricity when operated continuously.
5. Factor in maintenance costs
Air purifiers require regular filter replacement to function properly. HEPA and carbon filters typically last between six months and a year, depending on usage and pollution intensity. Always check if the purifier has a filter replacement indicator, which signals when a filter is saturated. Replacement filters can vary widely in price, so factoring in long-term maintenance costs is essential before buying.
Why it matters
Prolonged exposure to high levels of air pollution can contribute to chronic respiratory illnesses and conditions like Pre-COPD and Early COPD. While government policies such as GRAP address outdoor pollution, individuals can improve their indoor air quality using the right purifier.
Choosing a purifier with the correct CADR, reliable filters, and appropriate maintenance support can significantly reduce your exposure to PM2.5 and harmful gases — offering a practical line of defense for your lung health amid rising pollution levels.
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