Quick Answer
There is no single AQI value that CPCB defines as universally “safe.” For practical interpretation, AQI 0–50 is the CPCB Good category, while AQI 51–100 is Satisfactory.
Under India’s National Air Quality Index:
- 0–50 = Good
- 51–100 = Satisfactory
- 101–200 = Moderate
- 201–300 = Poor
- 301–400 = Very Poor
- 401–500 = Severe
CPCB associates the Good category with minimal impact and the Satisfactory category with possible minor breathing discomfort in sensitive people. The practical significance of an AQI value also depends on exposure duration, activity level, and individual sensitivity.
Introduction
Air quality can vary significantly across Indian cities depending on traffic, industrial activity, weather conditions, and seasonal factors. Many people check AQI values before going outside but are often unsure what AQI level is actually considered safe.
In India, the CPCB National Air Quality Index classifies AQI 0–50 as Good and 51–100 as Satisfactory. CPCB associates the Good category with minimal impact and the Satisfactory category with possible minor breathing discomfort in sensitive people.
Therefore, “safe AQI” is best understood as a practical way of asking about lower AQI ranges, rather than as a universal medical threshold. The health significance of an AQI value can also vary with exposure duration and individual sensitivity.
Understanding safe AQI ranges can help you make better decisions about outdoor exercise, commuting, and reducing unnecessary pollution exposure.
This guide explains what different AQI values mean and how to interpret them in relation to CPCB categories, exposure duration, activity level, and individual sensitivity.
Table of Contents
What Is AQI and Why Does It Matter?
AQI (Air Quality Index) is a system used to describe how clean or polluted the air is at a particular location. Instead of showing pollution measurements for individual pollutants separately, AQI combines multiple pollutants into a single number that is easier for the public to understand. To understand these numbers better, see How AQI is Calculated in India.
In India, the Central Pollution Control Board (CPCB) uses the National Air Quality Index framework to report air quality conditions across cities and monitoring stations. The underlying data comes from monitoring networks that continuously collect pollution measurements. Learn more in How Real-Time AQI Data Is Collected in India.
AQI is calculated using pollutants such as:
- PM2.5 (fine particulate matter)
- PM10 (coarse particulate matter)
- Nitrogen Dioxide (NO₂)
- Sulfur Dioxide (SO₂)
- Carbon Monoxide (CO)
- Ozone (O₃)
- Ammonia (NH₃)
- Lead (Pb)
As pollution levels increase, AQI values rise and potential health risks become greater.
For example:
- An AQI of 40 falls within the CPCB Good category.
- An AQI of 120 falls within the CPCB Moderate category.
- An AQI of 250 falls within the CPCB Poor category.
- An AQI of 400 falls within the CPCB Very Poor category.
The category provides the CPCB health-impact context for interpreting the number; the AQI value itself should not be treated as a universal medical threshold. These AQI values are generated using data from Air Pollution Monitoring Stations located across India.
What Is Considered a Safe AQI in India?
Under India’s National Air Quality Index, AQI 0–50 is classified as Good and AQI 51–100 as Satisfactory. These are the two lowest CPCB categories, but they should not be interpreted as a universal medical “safe zone.”
CPCB associates the Good category with minimal impact and the Satisfactory category with possible minor breathing discomfort in sensitive people. The practical significance of an AQI value also depends on exposure duration and individual sensitivity.
The CPCB AQI categories are shown below:
| AQI Range | CPCB Category | CPCB-associated health impact |
|---|---|---|
| 0–50 | Good | Minimal impact |
| 51–100 | Satisfactory | Minor breathing discomfort may occur in sensitive people |
| 101–200 | Moderate | Breathing discomfort may occur in people with lung or heart disease, children and older adults |
| 201–300 | Poor | Breathing discomfort may occur to people on prolonged exposure |
| 301–400 | Very Poor | Respiratory illness may occur on prolonged exposure |
| 401–500 | Severe | Respiratory effects may occur even in healthy people; existing diseases may be seriously affected |
For a detailed comparison between Indian and international air quality guidelines, see CPCB vs WHO Air Pollution Standards in India.
How to Read an AQI Number in India
The AQI number should be interpreted together with its CPCB category and the possible health impact associated with that category.
For example:
| AQI | CPCB Category | What it means |
|---|---|---|
| 40 | Good | Minimal impact |
| 75 | Satisfactory | Minor breathing discomfort may occur in sensitive people |
| 100 | Satisfactory | Upper end of the Satisfactory category |
| 103 | Moderate | Falls within the Moderate category |
| 150 | Moderate | Falls within the Moderate category |
| 200 | Moderate | Upper end of the Moderate category |
| 250 | Poor | Falls within the Poor category |
| 300 | Poor | Upper end of the Poor category |
| 400 | Very Poor | Falls within the Very Poor category |
| 500 | Severe | Highest value within the CPCB 0–500 scale |
A Real CPCB AQI Example: Kolkata
To see how the CPCB categories appear in real-world AQI reporting, we reviewed the CPCB National AQI portal for Kolkata.
| Date | CPCB-reported AQI | CPCB Category |
|---|---|---|
| 28 Sep 2026 | 95 | Satisfactory |
| 29 Sep 2026 | 104 | Moderate |
| 30 Sep 2026 | 133 | Moderate |
| 1 Oct 2026, 8:00 AM | 118 | Moderate |
What this shows: Kolkata’s reported AQI moved from 95 (Satisfactory) to 104 (Moderate) between 28 and 29 September. The change illustrates that AQI 101 marks the beginning of a different CPCB category; it should not be interpreted as a sudden medical “danger threshold.”
Is AQI 50 Safe?
AQI 50 is at the upper end of the CPCB Good category. CPCB associates the Good category with minimal impact.
This does not mean that the air is completely free of pollutants or that every person has identical risk. People who are more sensitive to air pollution may still need to consider their individual circumstances.
AQI 50 is therefore better described as a value within the CPCB Good category rather than as a universal medical “safe” threshold.
Is AQI 100 Safe?
AQI 100 is the upper limit of the CPCB Satisfactory category.
CPCB associates the Satisfactory category with possible minor breathing discomfort in sensitive people. AQI 100 should therefore be described as the upper end of the Satisfactory range rather than as a universally safe AQI value.
For people who are more sensitive to air pollution, exposure duration and individual health conditions are important when interpreting the reading.
AQI 50 vs AQI 100
Both values are within the two lowest CPCB categories, but they are not in the same category.
- AQI 50: Good
- AQI 100: Satisfactory
CPCB associates Good with minimal impact, while Satisfactory may involve minor breathing discomfort in sensitive people.
The difference therefore matters when interpreting the CPCB category, even though both values are below 101.
In most Indian cities, AQI values fluctuate throughout the day. Therefore, a single AQI reading should be interpreted alongside overall exposure duration and daily air quality trends.
Is AQI 150 Safe?
AQI 150 falls within the CPCB Moderate category.
CPCB associates the Moderate category with possible breathing discomfort among people with lung or heart disease, children and older adults.
AQI 150 is therefore different from AQI 100 because the two values belong to different CPCB categories. The practical effect of exposure can also depend on the duration and intensity of outdoor activity and individual sensitivity.
Is AQI 200 Dangerous?
AQI 200 is at the upper end of the CPCB Moderate category.
CPCB associates the Moderate category with possible breathing discomfort among people with lung or heart disease, children and older adults. AQI 200 is therefore still within the Moderate category; the next CPCB category, Poor, begins at AQI 201.
The appropriate response also depends on exposure duration, activity level and individual sensitivity.
Is AQI 300 Dangerous?
AQI 300 falls within the CPCB Poor category.
CPCB associates the Poor category with breathing discomfort to people on prolonged exposure. AQI 300 falls within the Poor category, while AQI 200 remains within the Moderate category.
The health significance of the reading can also depend on how long a person is exposed and on individual sensitivity.
Is AQI 500 Safe?
No. AQI 500 is the highest value within the CPCB Severe category. CPCB associates the Severe category with respiratory effects even in healthy people and serious effects on people with existing diseases.
How AQI Can Affect More Sensitive Groups
Children, older adults, and people with certain heart or lung conditions can be more vulnerable to air pollution. CPCB identifies children, older adults, and people with lung or heart disease as groups that may experience breathing discomfort within the Moderate AQI category.
How Should You Think About Outdoor Exercise and AQI?
Why Exposure Duration Matters
Many people focus only on the AQI number, but exposure duration also plays an important role.
For example:
A short outdoor activity and a several-hour outdoor training session at the same AQI can result in different total exposure because the duration of exposure is different.
This is one reason why air quality recommendations often consider both AQI levels and the amount of time spent outdoors.
Why Safe AQI Levels Can Be Different for Different People
Many people search for a single AQI value that is either “safe” or “unsafe.” In reality, air pollution affects people differently depending on age, health status, activity level, and exposure duration.
This is why the same AQI reading may have very different effects on different individuals.
Age Matters
Children and older adults are generally more sensitive to air pollution than healthy working-age adults.
Children:
- Have developing lungs
- Spend more time playing outdoors
- May inhale more air relative to their body size
Older adults:
- Often have reduced lung function
- May have underlying cardiovascular or respiratory conditions
- Can experience symptoms more easily during pollution episodes
As a result, AQI levels that are manageable for a healthy adult may cause discomfort for more vulnerable groups.
Existing Health Conditions Matter
People with certain medical conditions may be affected by air pollution at lower AQI levels.
Examples include:
- Asthma
- Chronic obstructive pulmonary disease (COPD)
- Heart disease
- Allergic respiratory conditions
For these individuals, even moderate pollution levels may trigger symptoms such as coughing, wheezing, chest tightness, or breathing discomfort.
Activity Level Matters
AQI exposure depends not only on pollution concentration but also on how much air a person breathes.
For example:
- Sitting indoors requires relatively little physical effort.
- Walking increases breathing rate.
- Running or playing sports significantly increases air intake.
This means two people exposed to the same AQI can receive very different pollution doses depending on their activity level.
Exposure Duration Matters
One of the most overlooked factors is exposure time.
A longer period of exposure can result in greater overall pollution intake.
However:
- Several hours outdoors
- Daily exposure during commuting
- Repeated exposure over multiple days
can increase overall pollution intake substantially.
Weather and Local Conditions Matter
AQI values can change throughout the day because of:
- Traffic patterns
- Wind speed
- Temperature inversions
- Industrial activity
- Seasonal factors
This is one reason why people should consider both current AQI readings and broader air quality trends rather than relying on a single number.
Daily AQI fluctuations are often influenced by weather conditions, atmospheric mixing, and local emissions. Learn more in Why Air Pollution Changes Daily.
What Should You Do at Different AQI Levels?
AQI values are most useful when they help people make practical decisions. While a single AQI reading does not determine exactly how every individual will respond, it can provide general guidance for outdoor activities and pollution exposure.
The table below summarizes the CPCB category and associated health context for each AQI range.
| AQI Range | CPCB Category | CPCB-associated health context |
|---|---|---|
| 0–50 | Good | Minimal impact |
| 51–100 | Satisfactory | Minor breathing discomfort may occur in sensitive people |
| 101–200 | Moderate | Breathing discomfort may occur in people with lung or heart disease, children and older adults |
| 201–300 | Poor | Breathing discomfort may occur to people on prolonged exposure |
| 301–400 | Very Poor | Respiratory illness may occur on prolonged exposure |
| 401–500 | Severe | Respiratory effects may occur even in healthy people; existing diseases may be seriously affected |
Frequently Asked Questions
What is the safe AQI limit in India?
CPCB does not define one AQI value as universally “safe.” AQI 0–50 is classified as Good and 51–100 as Satisfactory. CPCB associates the Satisfactory category with possible minor breathing discomfort in sensitive people.
What is the normal AQI level in India?
There is no single “normal” AQI value for all of India. AQI can vary by location, weather, season, time of day, and local emissions.
Is AQI 75 safe?
AQI 75 falls within the CPCB Satisfactory category. CPCB associates this category with possible minor breathing discomfort in sensitive people, so it is better described by its CPCB category rather than as a universal medical “safe” threshold.
Is AQI 100 safe?
AQI 100 is the upper end of the CPCB Satisfactory category. It should not be described as a universally safe medical threshold.
Is AQI 150 safe?
AQI 150 falls within the CPCB Moderate category. CPCB associates this category with possible breathing discomfort among people with lung or heart disease, children, and older adults.
Is AQI 300 hazardous?
AQI 300 falls within the Poor category, while AQI 200 remains within the Moderate category with breathing discomfort on prolonged exposure.
Conclusion
CPCB’s National Air Quality Index divides AQI into six categories, from Good to Severe. AQI 0–50 is Good, 51–100 is Satisfactory, 101–200 is Moderate, 201–300 is Poor, 301–400 is Very Poor, and 401–500 is Severe.
Instead of treating one AQI value as universally “safe” or “dangerous,” interpret the number together with its CPCB category, exposure duration, activity level, and individual sensitivity.
The Kolkata example also shows why the category matters: an AQI of 95 falls within Satisfactory, while 104 falls within Moderate. A category boundary is a classification change, not a sudden medical threshold.
Sources & References
This article uses information from official government publications, WHO guidance, IITM air-quality resources, and publicly available environmental data.
See our Sources & References page →
References
- Central Pollution Control Board (CPCB). National Air Quality Index (AQI) Framework
https://cpcb.nic.in/air-quality-index/ - Central Pollution Control Board (CPCB). Air Quality Index Information and Public Guidance
https://www.airquality.cpcb.gov.in/ccr/ - World Health Organization (WHO). Ambient (Outdoor) Air Pollution
https://www.who.int/health-topics/air-pollution - World Health Organization (WHO). Global Air Quality Guidelines (2021)
https://www.who.int/publications/i/item/9789240034228 - Indian Institute of Tropical Meteorology (IITM). Air Quality Early Warning System (AQEWS)
https://aqews.tropmet.res.in/