Mask, Air Purifier or Plants? What Actually Works Against Delhi Pollution

On 30 September, Delhi's AQI slipped back to 129, and satellites had already spotted 114 crop-burning events across six states in just two weeks (The Daily Jagran, citing ICAR-IARI and CPCB data). That is the quiet start. The loud part comes later.

So here is the short answer before you spend a rupee: a well-fitted N95 mask works outdoors, a HEPA air purifier works in a closed room, and houseplants do almost nothing for your air.

When does Delhi's pollution season actually peak?

Crop residue burning usually runs from 15 September to 30 November. Experts expect fire counts to climb through October and peak in the first ten days of November (India.com). This year Diwali falls in that same window.

Farm fires are only one piece. In 2024, stubble smoke made up more than 20% of Delhi's pollution on 14 days, while in 2025 that happened on just one day (India.com). Traffic, dust and local burning keep the baseline high either way. That's why personal protection matters even on "low fire" days.

A quick refresher on CPCB's scale: 101–200 is moderate, 201–300 poor, 301–400 very poor and 401–500 severe (The Daily Jagran). Most of the advice below kicks in once AQI crosses 200.

Do masks really protect you from air pollution?

Yes, but only one kind, and only when you wear it properly.

The Health Ministry's official advisory says disposable N95 or N99 masks are useful if you follow the instructions, the fit is close on your nose and mouth, and the exposure is short. It is blunt about the rest: "Paper masks, handkerchiefs, scarves and cloth are not effective" (MoHFW/NCDC Health Advisory on Air Pollution).

Think of your morning auto ride or the walk to the metro. That's where an N95 earns its place. A few things that decide whether it actually works:

• Fit beats brand. If you can feel air leaking from the sides when you breathe out, the mask is letting smog in too.
• Replace it as instructed. The advisory says to change masks after use as directed, not wear one all week.
• It's for short exposure. A mask is not a licence for a long outdoor run on a "very poor" day.

Do air purifiers actually work in Delhi homes?

They do, with an honest catch.

A research review found strong evidence that HEPA-filter purifiers reduce indoor PM2.5 and improve early markers of heart and lung health (Current Environmental Health Reports). A real-world experiment in a South Delhi apartment during winter found the same big drop indoors. But on the worst days, indoor air with the purifier running was still often dirtier than outdoor air in moderately polluted cities, and the dirtier it got outside, the less the purifier could keep up (Vyas et al., PLOS ONE).

So a purifier helps a lot. It just can't turn a leaky room into a hill station. To get your money's worth:

• Run it in one closed room, ideally the bedroom, where you spend eight hours.
• Match it to your room size. The Health Ministry suggests checking suitability, placement and area coverage before you buy.
• Change filters on time. A clogged filter is just an expensive fan.
• Skip ozone-generating purifiers. The advisory warns they add to indoor pollution (MoHFW/NCDC).

Can indoor plants purify the air?

Honestly, this is the biggest myth of the season.

The idea comes from small, sealed-chamber tests. When researchers at Drexel University reworked those results for real homes, they found you would need 10 to 1,000 plants per square metre of floor just to match what normal ventilation already does (Cummings & Waring, Journal of Exposure Science & Environmental Epidemiology).

And that review was about gases. Delhi's main winter problem is fine dust, PM2.5, and a money plant has no fan pulling air through it. Keep your plants because they make a room feel calmer. Just don't count them as protection.

What else can you do at home for free?

Some of the most useful steps in the Health Ministry advisory cost nothing (MoHFW/NCDC):

• Air out the house in the afternoon. On poor-AQI days, keep windows shut in the morning and late evening, and ventilate between 12 pm and 4 pm if needed. In the Delhi winter study, PM2.5 dipped to its daily low around 4–5 pm (PLOS ONE).
• Wet-mop, don't sweep. A jhaadu throws fine dust back into the air.
• Cut indoor smoke. Avoid agarbatti and mosquito coils in closed rooms, and don't light an angithi in a shut room.
• Set the AC to "recirculate" at home and in the car.
• Move your walk. Skip outdoor exercise in the early morning and late evening on bad days. If you're chasing a step count, an indoor or afternoon walk is the better trade. Here's how many steps you really need.
• Eat and drink normally well. The advisory calls a diet rich in fruits and vegetables plus adequate water a "no-regret" habit. It won't filter smog, but it never hurts. Not sure how much water you need? Try the water intake calculator.

Who needs to be most careful?

The advisory flags children under five, older adults, pregnant women, people with heart or lung conditions, and anyone who works outdoors, from traffic police to street vendors (MoHFW/NCDC). If someone at home has asthma or COPD, keep their prescribed medicines handy.

See a doctor if you notice breathlessness, chest discomfort or pain, dizziness, a persistent cough, or red, watery eyes.

Want the bigger picture on this winter? Read why El Niño 2026 matters for India, and how rain changed Delhi's air last week in our North India rain update.

FAQ

Which mask is best for Delhi pollution?

A disposable N95 or N99 that fits closely over your nose and mouth. Cloth and paper masks, handkerchiefs and scarves are not effective against smog, according to the Health Ministry.

Should I keep my air purifier on all day?

Run it whenever you're in the room, especially overnight, with doors and windows closed. Opening the door often lets polluted air back in and cuts the benefit.

Do snake plants or money plants clean the air?

Not in any way you'd notice. A peer-reviewed review found you'd need 10 to 1,000 plants per square metre to match normal ventilation.

Is it safe to go for a morning walk during smog season?

On days when AQI is above 200, the Health Ministry advises avoiding outdoor exercise in the early morning and late evening. Shift your walk indoors or to the afternoon.

This article is general information, not medical advice.