Air Pollution and Your Lungs: Practical Protection at Home
For much of the year, outdoor air in large parts of South Asia exceeds World Health Organization guideline levels by a wide margin. Individual measures cannot solve a systemic problem, but they can measurably reduce personal exposure, and the difference matters most for children, older adults and people with existing heart or lung disease.
What is in the air
PM2.5 is particulate matter under 2.5 micrometres across. This is the pollutant with the strongest evidence of harm because it is small enough to pass deep into the alveoli and into the bloodstream. Sources include vehicle exhaust, construction dust, industry, crop residue burning, waste burning and household cooking fuel.
PM10 includes coarser dust that mostly deposits in the upper airway.
Nitrogen dioxide comes largely from traffic and gas combustion and irritates the airways.
Ozone forms in sunlight from other pollutants and peaks on hot afternoons.
Sulphur dioxide comes from coal and heavy fuel.
Carbon monoxide and volatile organic compounds arise indoors from combustion, paints, adhesives and some cleaning products.
What it does to the body
Short-term exposure triggers airway inflammation, worsens asthma and COPD, increases respiratory infections and raises the rate of heart attacks and strokes in the days following a spike. Long-term exposure is linked to reduced lung growth in children, accelerated lung function decline in adults, lung cancer, ischaemic heart disease, hypertension, diabetes, adverse pregnancy outcomes and cognitive effects.
Symptoms of a bad exposure day include throat irritation, dry cough, eye stinging, chest tightness, headache and unusual fatigue.
Reading the air quality index
Indian AQI bands are:
- 0-50 Good
- 51-100 Satisfactory
- 101-200 Moderate
- 201-300 Poor
- 301-400 Very Poor
- 401-500 Severe
The index reports the worst single pollutant, so check which one is driving it. Above about 150, sensitive people should reduce outdoor exertion. Above 200, everyone should. Above 300, outdoor exercise is best avoided entirely.
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Reducing indoor exposure
Indoor levels usually track outdoor levels closely unless you intervene.
Filtration. A HEPA air purifier sized for the room is the intervention with the clearest measured effect. Match the device’s clean air delivery rate to the room volume, run it continuously in the room you sleep in, keep doors and windows closed while it runs, and replace filters on schedule. A purifier with an unchanged filter does very little.
Ventilation timing. Open windows when outdoor air is at its best, often mid-afternoon, rather than in the early morning, when a temperature inversion traps pollutants near the ground.
Stop adding indoor sources. Avoid indoor smoking, incense, mosquito coils, candles and unvented kerosene or biomass. Use a well-vented kitchen exhaust while cooking, since frying and tandoor-style cooking generate high PM2.5. Dry-mopping raises dust; damp mopping does not.
Reduce infiltration. Seal obvious gaps around windows and doors in the room you are protecting. Perfect sealing is neither necessary nor desirable.
Humidity. Keep relative humidity roughly 40-60 percent to limit dust mites and mould without adding moisture damage.
Masks
For outdoor exposure on bad days, a well-fitted N95 or FFP2 respirator filters fine particulates effectively. Surgical and cloth masks do not, because they neither filter to that size nor seal. Fit is what determines performance: no gaps at the nose bridge or cheeks, and facial hair along the seal defeats it. A respirator increases breathing effort, so people with significant heart or lung disease should discuss use with their doctor.
Behaviour that lowers dose
- Exercise indoors on high-AQI days, or shift outdoor activity to the cleanest hours
- Choose routes away from arterial roads; pollutant levels fall substantially a few hundred metres from heavy traffic
- Use recirculation mode in the car with a cabin filter in place
- Keep school-age children indoors during severe episodes, and ask about school policy
- Stop tobacco use, which multiplies the effect of ambient pollution
Who should have a plan
If you have asthma, COPD, ischaemic heart disease, heart failure or are pregnant, ask your doctor for a written action plan for high-pollution days, including whether to step up inhaled treatment. Keep reliever medication available and know the threshold at which you seek care.
Things that do not help
Salt lamps, plants as air purifiers at realistic densities, ionisers that generate ozone, nasal filters of unverified design, and “lung detox” supplements have no meaningful supporting evidence. Ozone-generating devices actively worsen indoor air quality.
This is general guidance. If pollution regularly worsens your breathing, that itself is a reason for a medical review rather than only equipment purchases.