Dhaka Air Pollution: When AQI Is Dangerous & Which Mask Works
Learn when AQI becomes unhealthy, what PM2.5 means, which respirators work, why fit matters, indoor-air steps and who needs extra caution.
“I went out for a morning walk and came back coughing.” On hazy days in Dhaka, that is increasingly familiar. The sky alone does not tell you enough: AQI helps translate air pollution into a practical health signal, and the right respirator matters far more than simply wearing any mask.
This guide explains when AQI becomes unhealthy, what PM2.5 means, why N95/KN95/FFP2 respirators differ from cloth or surgical masks, why fit and seal matter, how to reduce indoor exposure, and who should be especially careful.
When is AQI dangerous?
Bangladesh Department of Environment uses these AQI categories:
| AQI | Category | What to do |
|---|---|---|
| 0–50 | Good | Normal outdoor activity |
| 51–100 | Moderate | Generally acceptable; unusually sensitive people should watch symptoms |
| 101–150 | Unhealthy for Sensitive Groups | People with asthma/COPD/heart disease, older adults and children should reduce prolonged or heavy outdoor exertion |
| 151–200 | Unhealthy | Everyone should reduce prolonged outdoor exertion; sensitive groups should be more cautious |
| 201–300 | Very Unhealthy | Reduce unnecessary outdoor exposure; seek medical advice if symptoms worsen |
| 301–500 | Hazardous | Limit outdoor exposure as much as practical and follow any medical action plan |
Whatever AQI source or app you use, following the same source consistently makes trends easier to interpret. Check current AQI before going out.
What is PM2.5?
PM2.5 means fine particulate matter with a diameter of 2.5 micrometres or less. These particles are small enough to reach deep into the respiratory tract. WHO’s current annual PM2.5 air-quality guideline is 5 µg/m³. Historical annual averages in Dhaka have been many times higher, making long-term exposure relevant to both respiratory and cardiovascular health.
Which mask works for air pollution?
| Mask type | PM2.5 protection | Why |
|---|---|---|
| Cloth mask | Not reliable | Not designed to provide fine-particle filtration with a tight seal |
| Surgical mask | Limited for PM2.5 | Does not seal closely to the face, so fine particles can enter around the edges |
| N95 / KN95 / FFP2 / P2 respirator | Better choice when certified and well fitted | Designed for fine-particle filtration and a closer facial seal |
The key word is fit. Even a good filter loses much of its benefit if air leaks around the nose or cheeks.
How to wear an N95/KN95/FFP2 correctly
- Cover from the bridge of the nose to under the chin.
- Press the nose clip, if present, to follow the shape of the nose.
- Check for gaps around the cheeks and sides.
- Notice whether air leaks around the edges when you breathe out.
- Dense facial hair can interfere with the seal.
- Replace the respirator if it becomes damp, dirty, damaged or difficult to breathe through.
- Check the packaging for the stated certification or standard; “N95-style” wording alone is not enough.
Should children wear adult N95/KN95 respirators?
Adult respirators may not seal properly on a smaller face. Do not assume an adult N95 or KN95 will protect a child effectively. On high-pollution days, reducing outdoor play, improving indoor air and asking a paediatric clinician for guidance is the safer approach, especially for children with respiratory disease.
How to keep indoor air cleaner
- When outdoor AQI is very poor, avoid leaving doors and windows unnecessarily open.
- If you use an air purifier, follow room-size and device instructions.
- Use recirculation mode on air conditioning where appropriate.
- Do not smoke indoors.
- Reduce mosquito-coil, incense and other indoor smoke sources.
- Use exhaust or suitable ventilation for cooking smoke; ventilate when outdoor air is better.
- Damp cleaning can reduce airborne dust compared with dry sweeping.
Who needs extra caution?
| Group | What helps |
|---|---|
| Asthma/COPD | Reduce outdoor exertion when AQI is high and follow the prescribed inhaler plan |
| Heart disease | Avoid heavy outdoor exertion; seek assessment for new chest discomfort |
| Older adults | Shift or shorten outdoor walks during pollution peaks |
| Children | Reduce outdoor play and prioritize cleaner indoor air |
| Pregnancy | Reduce exposure on high-AQI days and seek advice for persistent symptoms |
| Outdoor workers | Certified well-fitted respirators, breaks and exposure reduction are important |
Can you exercise outside on a polluted day?
Once AQI rises above 100, sensitive groups should reduce prolonged or heavy outdoor exercise. Above 150, everyone should consider reducing intensity and duration. Indoor exercise or a lower-AQI time of day may be a better option.
When should you seek medical care?
- new or worsening shortness of breath
- wheezing that does not improve with the usual prescribed plan
- new chest pain or pressure
- bluish lips or face
- fast breathing or chest indrawing in a child
- severe dizziness, fainting or confusion
- persistent cough with blood, unexplained weight loss or prolonged symptoms
Common myths
| Myth | Reality |
|---|---|
| “Any mask protects against pollution.” | Fine-particle protection depends on a certified respirator and a good fit. |
| “A loose N95 works just as well.” | Leaks around the seal reduce protection. |
| “AQI matters only if you have asthma.” | High AQI can affect everyone, although sensitive groups are affected earlier. |
| “Indoor air is always safe.” | Outdoor pollution enters buildings, and indoor smoke sources also matter. |
Frequently asked questions
When does AQI become unhealthy?
101–150 is unhealthy for sensitive groups; 151–200 is unhealthy; 201–300 is very unhealthy; 301–500 is hazardous.
Which mask is better for air pollution?
A certified N95, KN95, FFP2 or P2 respirator can reduce fine-particle exposure when it fits well.
Does a surgical mask protect against PM2.5?
It is not a reliable substitute for a fitted respirator against fine-particle pollution because it does not seal closely to the face.
Why does respirator fit matter?
If unfiltered air leaks around the edges, the filtration benefit is reduced.
Can a child use an adult N95?
An adult respirator may not seal properly on a smaller face. Seek child-specific fit and medical guidance when needed.
What is PM2.5?
Fine particles with a diameter of 2.5 micrometres or less that can travel deep into the respiratory tract.
Should windows stay closed on a high-AQI day?
When outdoor air is very polluted, reduce unnecessary opening; ventilate when outdoor air quality improves.
Can an air purifier help?
An appropriate purifier can reduce indoor particle exposure when used according to room-size and device instructions.
Sources
- Bangladesh Department of Environment — Ambient Air Quality / AQI categories.
- WHO — Global Air Quality Guidelines.
- AirNow — Air Quality 101.
- Better Health Channel — Face masks for environmental hazards.
- IQAir — Dhaka air-pollution reporting and protection advice.
- Prothom Alo — Bangladesh respiratory specialists on pollution-related illness.
This article is for general health information. Check respirator certification, fit and reuse instructions against the manufacturer or applicable standard. People with asthma, COPD, heart disease, pregnancy or persistent breathing symptoms should seek clinician guidance when needed.
[executed on device: Aziz-MacBook.local (e21e2c25-9602-4c8d-b57a-8ddf9e985cd7)]
Related Products
