How air pollution affects health
What PM2.5 does in the body, who is most at risk, and why lowering exposure helps at any level.
In the body
Fine particles inflame the airways and lungs. That inflammation, and particles or their chemicals reaching the bloodstream, affect the heart and blood vessels as well as the lungs. Effects range from irritation that passes within days to serious long-term disease.
Common short-term symptoms
- Itchy, watery eyes; runny nose; sore or scratchy throat
- Cough, phlegm, chest tightness
- Wheezing or breathlessness, especially in people with asthma or COPD
- Headaches and tiredness
Most of these ease when exposure drops. If they don’t, or if someone has a heart or lung condition and their usual symptoms worsen, they should contact their doctor.
Serious effects
- Asthma attacks and COPD flare-ups, more hospital visits
- Heart attacks, abnormal heart rhythms and strokes in people already at risk, sometimes within hours to days of a spike
- Lung infections, especially in young children and older adults
- Over years: higher risk of heart disease, stroke, lung cancer, chronic lung disease and possibly diabetes and dementia
- In pregnancy: higher risk of low birth weight and preterm birth
- In children: reduced lung growth and more respiratory infections
Who is most at risk
| Group | Why |
|---|---|
| Older adults | More likely to have heart or lung disease; lower reserve to cope with stress on the body |
| Babies and young children | Breathe more air for their size; lungs still developing; spend time close to the ground |
| Pregnancy | Effects on the developing baby |
| Heart disease, previous heart attack or stroke | Pollution can trigger events |
| Asthma, COPD, other lung disease | Airways already inflamed |
| Diabetes | Associated with higher cardiovascular risk |
| Outdoor workers, people in poorly sealed homes | Higher exposure |
US EPA also lists people with lower incomes, who often face higher exposure and less access to protection. India’s health ministry adds children under 5, pregnant women and outdoor workers such as traffic police, construction and brick-kiln workers.
The sensitive groups section has practical guidance for each.
India’s advice by AQI category
Summarised from the health ministry’s handbook for community health workers, for people in sensitive groups:
| India AQI | What sensitive people should do |
|---|---|
| Satisfactory / Moderate | Avoid long or heavy exertion outdoors |
| Poor | Avoid heavy exertion outdoors. Keep doors and windows closed, while still ventilating when needed |
| Very Poor | Stay indoors as much as possible and keep activity light. Wear a close-fitting N95/N99 outdoors. No burning, candles or smoking indoors |
| Severe | Go out only if urgent, always with an N95/N99 |
Any reduction helps
There is no level of PM2.5 known to be completely safe. Health risk rises steadily with exposure. That’s why the WHO guideline is low (15 µg/m³ for a 24-hour average, 5 µg/m³ for an annual average), and why bringing a bedroom from 250 down to 30 µg/m³ is a big win even if it never reaches the guideline.