Air pollution is not only a visibility problem. Fine particles and gases can affect the eyes, airways, lungs and cardiovascular system, and the risk depends on both the pollution level and how long a person is exposed.
India's Air Quality Index, or AQI, turns monitoring data into six public categories—from Good to Severe. Understanding those categories is more useful than reacting to a hazy sky alone, because dangerous particles may be present even when pollution is not clearly visible.
This practical guide explains what each AQI range means, who needs extra care, how to plan outdoor activity, when a close-fitting respirator may help and how to reduce indoor exposure without falling for misleading “instant detox” claims.
India AQI Categories: What the Numbers Mean
| AQI | Category | CPCB health statement in plain language |
|---|---|---|
| 0–50 | Good | Minimal impact expected. |
| 51–100 | Satisfactory | Sensitive people may experience minor breathing discomfort. |
| 101–200 | Moderate | People with lung, asthma or heart conditions may experience discomfort. |
| 201–300 | Poor | Prolonged exposure can cause breathing discomfort for many people. |
| 301–400 | Very Poor | Prolonged exposure can lead to respiratory illness, especially in vulnerable people. |
| 401–500 | Severe | Healthy people can be affected, while existing heart or lung disease may be seriously aggravated. |
The AQI is a communication tool, not a medical diagnosis. A city's displayed figure can also differ between monitoring stations and change during the day. Check the station nearest to your area through the CPCB National AQI portal.
What Pollutants Does AQI Track?
India's AQI can be calculated from monitored pollutants including PM2.5, PM10, nitrogen dioxide, sulphur dioxide, carbon monoxide, ozone, ammonia and lead. The pollutant producing the highest sub-index can drive the overall AQI at a location.
PM2.5
PM2.5 refers to fine particles with an aerodynamic diameter of 2.5 micrometres or less. Their small size allows them to travel deep into the lungs. Common sources can include combustion, traffic, industry, biomass burning and secondary particles formed in the atmosphere.
PM10
PM10 includes larger inhalable particles. Road dust, construction, soil and mechanical processes can contribute. A cloth or ordinary loose surgical mask is not designed to provide reliable filtration of these airborne particles.
Gases
Ozone, nitrogen dioxide, sulphur dioxide and carbon monoxide behave differently from particles. A particle filter does not remove every gas, which is one reason no mask or purifier should be marketed as complete protection from all air pollution.
Who Needs Extra Care?
The National Centre for Disease Control identifies several groups as more vulnerable to pollution-related health effects:
- Children, particularly those under five
- Older adults
- Pregnant women
- People with asthma, chronic lung disease or heart disease
- People with diabetes or other chronic conditions
- Outdoor workers and people spending long periods near traffic or dust
- Anyone recovering from a respiratory illness
Vulnerability does not mean every person will have the same reaction. Follow an existing treatment plan and seek individual guidance from a qualified clinician when a health condition makes exposure decisions difficult.
Symptoms That Should Not Be Ignored
Short-term exposure can be associated with irritation of the eyes, nose or throat, coughing, wheezing, breathlessness and chest discomfort. Headache, unusual fatigue or worsening of a known respiratory condition may also occur.
Seek urgent medical attention for severe breathing difficulty, chest pain, confusion, bluish lips or face, fainting, or a rapidly worsening asthma attack. Do not delay emergency care while trying home remedies or waiting for the AQI to improve.
AQI-Based Activity Plan
| AQI situation | Practical response |
|---|---|
| Good or Satisfactory | Normal activity is generally reasonable; unusually sensitive people should monitor symptoms. |
| Moderate | People with heart or lung conditions may reduce prolonged heavy exertion near traffic. |
| Poor | Reduce long or intense outdoor exercise, especially for vulnerable groups. |
| Very Poor | Move strenuous activity indoors where the air is cleaner and limit unnecessary exposure. |
| Severe | Avoid outdoor exertion where possible, follow local health advice and watch for symptoms even during light activity. |
These are general precautions, not personalised medical instructions. Local authorities may issue stronger directions during an episode.
Do N95 Masks Protect Against Air Pollution?
A close-fitting particulate respirator can reduce exposure to particles when outdoor exposure cannot be avoided. The World Health Organization's practical guidance recommends a respirator approved to remove at least 95% of particles, such as a properly fitting N95, KN95 or FFP2-type respirator, rather than an ordinary face covering.
Fit matters as much as the label
- The respirator should seal around the nose and mouth without obvious gaps.
- Facial hair in the seal area can reduce performance.
- Perform the manufacturer's seal check each time.
- Replace a damaged, dirty, wet or difficult-to-breathe-through respirator.
- Do not buy products making unverifiable “100% pollution protection” claims.
A respirator mainly addresses particles. It does not provide complete protection against every pollutant gas, and it should not be used as a reason to spend longer in heavily polluted air.
How to Reduce Indoor Air Pollution
Close openings during a high-pollution episode
When outdoor pollution is high, closing windows and doors can reduce the entry of outside particles. Reopen or ventilate when outdoor conditions improve, because a permanently sealed room can allow indoor pollutants, moisture and carbon dioxide to build up.
Control indoor sources
Avoid smoking, incense, candles, mosquito coils and unnecessary frying or burning in poorly ventilated rooms. Use an exhaust fan during cooking where it vents safely outdoors, and avoid dry sweeping that sends settled dust back into the air.
Use a suitable air cleaner when needed
WHO reports that portable air cleaners can reduce indoor particulate levels when correctly selected and operated. Choose a unit with a genuine HEPA filter and a clean-air delivery rate suitable for the room. Position it where airflow is not blocked and replace filters according to the manufacturer's instructions.
Avoid ionising or ozone-generating devices. Ozone is itself a respiratory irritant. An expensive purifier that is too small for the room, poorly placed or operated only briefly may deliver limited benefit.
Prioritise the bedroom
If only one room can be managed, the bedroom may be a practical priority because people spend many hours there. Keep the door and windows appropriately closed during an outdoor pollution peak, reduce indoor sources and operate a correctly sized cleaner continuously if available.
Travel and Commuting Tips
- Check AQI before leaving, not after symptoms start.
- If possible, choose routes away from heavy traffic and construction.
- Shift exercise to a cleaner time or indoor location.
- In a vehicle during a high-pollution episode, close windows and use cabin air recirculation for limited periods.
- Maintain the vehicle's cabin filter and avoid engine idling.
- Outdoor workers should use employer-provided controls and appropriate protective equipment; a mask is not a substitute for workplace safety measures.
Common Air-Pollution Myths
“If I cannot see smog, the air is safe”
False. Fine particles and gases may be present without dramatic haze. Use monitored data rather than appearance alone.
“Houseplants can replace an air purifier”
Houseplants can make a room pleasant, but ordinary numbers of plants should not be treated as a substitute for source control, ventilation decisions or effective filtration.
“A cloth mask blocks PM2.5”
A loose cloth covering does not provide the seal and tested particle filtration of an approved respirator.
“Steam or detox drinks remove pollution from the lungs”
No drink or steam treatment can be claimed to instantly remove inhaled particles. Hydration and a balanced diet support general health but are not pollution antidotes.
“Running is always healthier, whatever the AQI”
Physical activity is generally beneficial, but heavy exercise increases breathing rate and the amount of polluted air inhaled. During very high pollution, change the time, route or location.
How to Check AQI Correctly
- Use the official CPCB portal or a trusted source that identifies its monitoring station.
- Choose the station nearest to your actual location.
- Check the time of the reading and the dominant pollutant.
- Compare the current category with your planned activity and health condition.
- Review local advisories during severe episodes, fires or dust events.
Do not compare a sensor beside a busy road directly with a station several kilometres away and assume one must be wrong. Local sources, wind and monitoring methods can produce real differences.
Frequently Asked Questions
What is a safe AQI?
CPCB calls 0–50 Good and 51–100 Satisfactory. “Satisfactory” does not mean zero risk for every sensitive person, so symptoms and medical conditions still matter.
Should children wear N95 masks?
Fit, breathing comfort, age and health conditions require special consideration. Parents should follow current public-health guidance and seek professional advice for a child with asthma or another respiratory condition.
Can an air conditioner clean polluted air?
An air conditioner mainly controls temperature. Particle reduction depends on the filtration system, filter grade, maintenance and how much outside air enters. It should not automatically be treated as a HEPA air cleaner.
Should windows remain closed all day?
Not automatically. Closing them during an outdoor pollution peak may reduce infiltration, but ventilation may be needed when outside air improves or indoor sources accumulate.
When should I see a doctor?
Seek medical advice when coughing, wheezing or breathlessness is persistent, when a chronic condition worsens, or when symptoms interfere with normal activity. Severe breathing difficulty or chest pain requires urgent care.
Conclusion
The most useful response to air pollution is a combination of accurate information and sensible exposure reduction. Check the nearest monitoring station, adjust strenuous outdoor activity, control indoor sources and use effective filtration where appropriate.
A well-fitting particulate respirator can help when exposure cannot be avoided, but it is not complete protection and does not replace cleaner air. Vulnerable people should act earlier and follow their healthcare plan.
Official Sources
- Central Pollution Control Board: National AQI Portal
- CPCB: About the National Air Quality Index
- NCDC: Public Health Advisory on Air Pollution and Health
- WHO: Air pollution personal interventions and risk communication
- WHO: Personal-level actions to reduce exposure
Medical disclaimer: This article provides general public-health information and is not a diagnosis or a substitute for personalised medical care. AQI, local advisories and health recommendations can change; verify the live official information for your area.
