Air Quality & Air Purifier FAQ | Common Questions Answered Simply
Air Quality & Air Purifier – Frequently Asked Questions
This page answers some of the most common questions people have about air quality, indoor pollution, and air purifiers — explained simply and practically.
Air Quality & AQI
What is a good AQI level?
An AQI value below 50 is considered good for everyone.
Between 50 and 100, most people are comfortable, though sensitive individuals may notice minor effects.
Is AQI the same as PM2.5?
No.
- AQI is an index that combines multiple pollutants into one number
- PM2.5 is a specific pollutant — fine particulate matter
PM2.5 often has the largest impact on AQI and health.
Why is winter AQI usually worse in Indian cities?
Winter conditions often include:
- Lower wind speeds
- Temperature inversion
- Increased emissions
These factors trap pollutants close to the ground, raising AQI levels.
Does rain really clean the air?
Yes, to some extent.
Rain helps remove particulate matter from the air, which is why AQI often improves during the monsoon. However, pollution can return once rain stops.
Indoor Air Quality
Is indoor air always cleaner than outdoor air?
Not always.
Indoor air can be polluted by:
- Cooking fumes
- Incense and agarbatti
- Mosquito coils
- Cleaning chemicals
- Outdoor pollution entering indoors
In many cases, indoor PM2.5 levels can be similar to outdoor levels.
How much time do we actually spend indoors?
Most people spend 80–90% of their time indoors, which is why indoor air quality has a significant impact on long-term health.
Can opening windows always improve indoor air?
No.
- When outdoor AQI is good → ventilation helps
- When outdoor AQI is poor → ventilation may worsen indoor air
Timing ventilation based on outdoor conditions is important.
PM2.5 & Health
What PM2.5 level is considered safe indoors?
As a general guideline:
- Below 10–12 µg/m³ is very good
- 12–35 µg/m³ is acceptable for most people
- Sustained levels above this should be reduced if possible
These are reference values, not strict limits.
Who is most affected by PM2.5?
People more sensitive to PM2.5 include:
- Children
- Elderly individuals
- People with asthma or allergies
- Those with heart or lung conditions
Can PM2.5 cause long-term health problems?
Long-term exposure to elevated PM2.5 levels has been associated with increased risk of respiratory and cardiovascular problems. Reducing continuous exposure is important.
Air Purifiers
Do air purifiers really work?
Yes — when used correctly.
Air purifiers with true HEPA filters can significantly reduce indoor particulate levels, especially PM2.5.
Can an air purifier clean the whole house?
Usually not.
Most air purifiers are designed for single rooms. Multiple units are needed for multiple rooms.
Do air purifiers remove gases or odours?
HEPA filters remove particles, not gases.
- Activated carbon filters help reduce odours and some chemical fumes
- No household purifier removes all gases
Are air purifiers safe to use all night?
Yes.
Most purifiers are designed for continuous operation and are often used overnight, especially in bedrooms.
How long should an air purifier be run?
For best results:
- Run for several hours continuously
- Use auto or low-to-medium fan speeds for long durations
Short, occasional use is less effective.
Do air purifiers increase electricity bills?
Most household air purifiers consume modest power, similar to a ceiling fan or small appliance.
Running costs are usually low compared to their benefits.
How often do filters need to be replaced?
This depends on:
- Pollution levels
- Usage hours
- Filter type
Typically:
- HEPA filters last 6–12 months
- Pre-filters may need more frequent cleaning
Always follow manufacturer guidance.
Choosing & Using Air Purifiers
Is a more expensive purifier always better?
Not necessarily.
Performance depends on:
- CADR
- HEPA quality
- Room size match
Some mid-range models perform as well as expensive ones for typical rooms.
Is one large purifier better than two small ones?
Often, two correctly sized purifiers placed in key rooms work better than one large unit trying to cover everything.
Can I rely only on an air purifier?
No.
Air purifiers are support tools. Best results come from:
- Reducing indoor pollution sources
- Using ventilation wisely
- Using purifiers correctly
Final thought
Air quality management is about reducing long-term exposure, not achieving perfect numbers.
Understanding air quality, measuring sensibly, and using tools like air purifiers wisely can make a meaningful difference over time.
If you’re new to the topic, start with: