Delhi Air Pollution: What Actually Works at Home
Delhi NCR averages PM2.5 of 80-110 µg/m³ year-round — 6-7× the WHO 15 µg/m³ guideline. October to February brings AQI 300-500+. None of it is going away soon. This is a practical guide to what actually reduces your home’s pollution exposure, in order of effectiveness, with honest notes on what doesn’t.
The Delhi reality, briefly
Three patterns to internalise:
1. PM2.5 is elevated 9-10 months of the year, not just winter. - April-September baseline: 50-90 µg/m³ (still 3-6× WHO) - October-November ramp: 100-200 µg/m³ - November-January peak: 200-450 µg/m³ daily, 600+ during specific events - February tail: 100-200 µg/m³
2. The “Diwali week” myth. Diwali fireworks are real but contribute ~10-15% of October-November PM2.5. The dominant sources year-round are vehicle emissions, construction, industrial belt (Bawana / Narela / Manesar), and post-monsoon stubble burning in Punjab/Haryana. Cleaning up Diwali alone wouldn’t move the needle much.
3. Indoor PM2.5 closely tracks outdoor. Without mechanical ventilation + filtration, indoor PM2.5 is 60-110% of outdoor. “Stay inside” is bad advice when indoor is barely better than outdoor — and CO₂ accumulates inside faster than outside.
What actually reduces PM2.5 in your Delhi home
Ranked by real-world effectiveness based on measurements across our NCR installs and the peer-reviewed literature.
1. Positive-pressure fresh air system with H13 HEPA — works year-round
A residential fresh air system pulls 500 m³/h of outdoor air through clinical-grade H13 HEPA filtration and pushes it into your home, creating slight positive pressure (10-25 Pa) that prevents unfiltered air from leaking in.
Real measurements across NCR installs:
| Outdoor AQI band | Indoor PM2.5 (with aqi0) |
|---|---|
| 100-150 (April-September baseline) | < 10 µg/m³ |
| 200-300 (October-November build-up) | 15-25 µg/m³ |
| 300-450 (November-January peak) | 20-35 µg/m³ |
| 450-600 (Diwali / inversion events) | 30-45 µg/m³ |
Indoor stays under WHO 24-hr guideline (15 µg/m³) for most of the year. Even during Diwali week peaks, indoor is typically 1/10th of outdoor.
It also handles CO₂ (continuously below 1,000 ppm), VOCs, and cooking-fume retention — the things air purifiers can’t.
2. Air purifier per room — works on moderate days, stalls when AQI crosses 250
A premium H13 HEPA air purifier reduces PM2.5 by 60-85% in a closed room of correct size (CADR ≥ 300 m³/h for a typical Delhi 2-3 BHK bedroom) — on a “moderate” outdoor day. Performance drops sharply on bad-air days, which in Delhi NCR means most of November to January. An independent 9-day Delhi test of a premium purifier measured 49% average PM2.5 reduction, indoor air still 2.5× the WHO limit at its cleanest. The limitation is the category, not any one brand. (Why purifiers stall above outdoor AQI 250 →)
Where it works: the bedroom you sleep in, on a “moderate” outdoor day. The study you work in. Specific rooms. Where it doesn’t: anywhere else simultaneously, plus it cannot reduce CO₂, plus performance collapses once outdoor AQI exceeds 250.
Cost reality for a 4-room Delhi home: 4 purifiers × ₹25,000-40,000 = ₹1-1.6 lakh upfront. Plus ₹16,000-32,000/year filter replacement. Plus ₹800-1,600/month electricity (4 purifiers running 24/7).
Full purifier vs fresh air comparison → Are air purifiers enough for Delhi? →
3. Aggressive kitchen exhaust (chimney) during cooking
Cooking on gas/LPG without working chimney exhaust spikes indoor PM2.5 to 200-500 µg/m³ during cooking. This is the single biggest preventable indoor source.
What to do: - Use chimney on high for full duration of cooking + 10 minutes after - Keep kitchen door closed during cooking (contains the point source) - Upgrade chimneys with under 1,200 m³/h suction — they’re underpowered for Indian cooking
This alone, done consistently, can cut average daily indoor PM2.5 by 30-40% in homes with poor chimney habits.
4. Eliminate indoor combustion sources
Each of these adds significantly to indoor PM2.5 for the duration they burn:
- Incense (agarbatti, dhoop): 50-400 µg/m³ during burning
- Mosquito coils: Combustion + chemicals; particularly bad
- Candles, especially paraffin: 50-150 µg/m³
- Diyas / oil lamps: During festivals, contribute notably
- Indoor smoking: PM2.5 contribution dwarfs everything above
Free fix. Substitute electric diffusers, LED candles, plug-in mosquito repellents, designate outdoor smoking.
5. HEPA-filter vacuum, damp-mop instead of broom
Sweeping with a broom kicks settled dust back into the air — indoor PM2.5 spikes 3-5× during and 30-60 minutes after. Damp-mopping captures dust without re-aerosolising it. A HEPA-filter vacuum (₹15,000-30,000) doesn’t blow particles out the back the way non-HEPA vacuums do.
Real but modest impact on daily averages; significant during/after the activity.
What doesn’t work in Delhi — debunked
N95 masks indoors
Masks reduce inhaled PM2.5 (effective when properly fitted outdoors), but you can’t wear one for 16 hours at home. Useful for outdoor commute / exercise during severe AQI; doesn’t solve the home problem.
“Air-purifying” houseplants
NASA’s 1989 sealed-chamber study is widely misquoted. Real-world peer review (Cummings & Waring, 2020, Journal of Exposure Science & Environmental Epidemiology): “Potted plants do not improve indoor air quality.” You’d need 100-1,000 plants per square metre of floor space to match the air-exchange effect of a single outdoor-air intake. Effective PM2.5 reduction at residential plant density: zero.
Have plants because they look nice. Don’t expect them to clean your air.
Air ionisers / ozone generators
Ionisers produce ozone as a byproduct. Ozone is itself a respiratory irritant — and at concentrations needed to “clean” air, it’s harmful. Many ioniser-based devices have been flagged by air-quality researchers as potentially worsening indoor air. Avoid.
“Open the windows for fresh air”
In Delhi, outdoor PM2.5 is 50-500 µg/m³ for 9-10 months of the year. Opening a window trades CO₂ for direct PM2.5 exposure. Specific exception: the few days a year when AQI is below 50 (typically August monsoon peak). On those days, brief window-open ventilation is fine.
Sealing the home tighter (without ventilation)
Sealing window/door gaps does reduce outdoor PM2.5 infiltration — but it traps CO₂, raises humidity, and concentrates indoor sources. Only sensible if combined with mechanical ventilation. Counterproductive on its own.
Central HVAC with “fresh air mode”
Most central HVAC fresh-air dampers are 5-10% of total airflow with MERV 8-11 filtration. That’s not enough air exchange to control CO₂, and not enough filtration to meaningfully reduce PM2.5. Useful as a supplement; not a solution.
The right order to fix it
If you have ₹1 lakh and want to know where it goes:
- Install a fresh air system with H13 HEPA — ₹70,000 + GST (₹82,600 all-in), ~₹170/month electricity. Covers your whole home year-round. Handles PM2.5 + CO₂ together. Add ₹12,500 + GST/year AMC and the aqi0 AQI monitor is included free when on the same invoice.
- Use kitchen chimney religiously — already paid for; just behavioural.
- Eliminate incense / mosquito coils / indoor smoking — free.
- Get a ₹3,000-₹5,000 PM2.5 + CO₂ monitor — makes your air quality visible and converts every other behavioural fix into something you can verify.
That’s it. Methods 5-10 from our 10-method ranked guide (HEPA vacuum, no indoor laundry, etc.) are real but marginal compared to the first four.
What if I can’t install a fresh air system right now?
- Renting under 12 months? Get one good H13 HEPA purifier (CADR ≥ 300) for the bedroom. Run kitchen exhaust religiously. Eliminate incense / coils. Plan for a fresh air system at your next move.
- Budget under ₹40,000 today? Same as above — bedroom purifier is the best single buy. The fresh air system can come once the budget is ready.
- Temporary Diwali protection only? A bedroom purifier covers the worst week. Don’t expect year-round results.
Frequently asked
Will a fresh air system work during Delhi’s worst AQI 500+ days?
Yes. Real measurements: when outdoor AQI hit 500+ during Diwali 2024 in Gurugram, indoor PM2.5 in homes with aqi0 systems stayed at 30-45 µg/m³ — about 1/10th of outdoor. Indoor AQI was around 90-110 (“Moderate”) while outdoor was “Severe-plus”.
Does it work in summer?
Yes, all year. Summer baseline AQI in NCR is 100-200 (PM2.5 of 50-90 µg/m³). The system reduces this to under 15 µg/m³ indoors. Bonus: continuous fresh air keeps CO₂ in check during summer when ACs are on and homes are sealed.
What about winter heat loss?
Incoming filtered air comes in at outdoor temperature. In Delhi winter (10-25°C lows), this is mildly cold for 4-6 weeks. Most homes’ room heaters or AC heat-mode handle this without noticeable bill increase. A winter heater add-on is in development for late 2026 to pre-warm incoming air.
How long does this take to install?
A single day. 4-6 hours typical. Site visit first (within 48-72 hours of enquiry). Install within 5-7 days of confirmed order. Full team handles everything except toughened-glass cutting (handled by your glass vendor).
What’s the long-term Delhi outlook?
Delhi’s PM2.5 has stayed stubbornly elevated since 2014 measurements began. Sources are diverse and remediation is slow. Reasonable to assume residential indoor air will remain a do-it-yourself problem for the next decade. The fresh air system is a 10-year asset.
Related reading
- What is a fresh air system?
- How to reduce PM2.5 at home in India — 10 methods, ranked
- PM2.5 safe levels in India
- Are air purifiers enough for Delhi?
- CO₂ in your bedroom
Talk to us
aqi0 installs across Gurugram, South Delhi, Noida, and Faridabad. Free site visit, no obligation. Our team measures your current PM2.5 and CO₂ on-site, recommends a configuration, and gives you a quote.
WhatsApp +91 96676 72740 • [email protected]