Home appliances
In Delhi-NCR winters an under-sized purifier is a placebo. The one number that decides effectiveness is CADR against your room's area — everything else is packaging.
A few questions about your situation, not about the product.
Answer all 3 questions to see the spec sheet to shop with.
Clean Air Delivery Rate — volume of filtered air produced per hour.
Why it matters
Room area (sq ft) x 1.6 ≈ CADR needed for ~5 air changes per hour.
What to check
Some brands quote 'coverage area' at only 2 air changes — too slow for polluted cities.
Captures 99.95% of 0.3 micron particles.
Why it matters
This is what removes PM2.5. 'HEPA-type' or 'HEPA-like' does not qualify.
What to check
Look for the H13 or H14 grade printed on the filter itself.
Carbon that adsorbs smoke, VOCs and odours.
Why it matters
A thin carbon mesh does almost nothing; usable units carry several hundred grams of granular carbon.
What to check
Ask for carbon weight in grams, not 'carbon layer'.
Replacement price and months of use.
Why it matters
In high-pollution cities filters last 6–8 months, not the claimed 12. This is the real running cost.
What to check
Get the replacement filter price before buying the machine.
dB level at the fan speed you'd run overnight.
Why it matters
Quoted noise is on sleep mode, which often delivers a fraction of the CADR.
What to check
Ask for dB and CADR at the same speed setting.
Extra charged-particle features.
Why it matters
Some ionisers produce ozone, which irritates lungs.
What to check
Prefer purifiers where the ioniser can be switched off.
Bedroom units around 200 CADR to living-room units of 400+ CADR.
