Air quality reference
AQI Levels & Categories: Chart, Colours and Ranges
India's AQI has six categories: Good (0–50, green), Satisfactory (51–100), Moderate (101–200, yellow), Poor (201–300, orange), Very Poor (301–400, red) and Severe (401–500, maroon). Sensitive groups should take precautions above 100; above 300 affects everyone.
Air quality is a critical factor affecting public health and daily life, and understanding the Air Quality Index (AQI) is essential for making informed decisions about outdoor activities and health precautions. The AQI is a standardized measure used by governments worldwide to communicate the level of air pollution and associated health risks. This article provides an in-depth look at the AQI levels and categories, focusing on the Indian Central Pollution Control Board's (CPCB) six-category system, while also comparing it to the United States Environmental Protection Agency's (EPA) scale. By understanding the what the AQI number means, you can better protect yourself and your loved ones from the adverse effects of air pollution.
Understanding the Air Quality Index (AQI)
The AQI is a numerical scale designed to communicate the level of air pollution to the public. It takes into account the concentration of major pollutants such as PM2.5, PM10, NO2, O3, CO, SO2, NH3, and Pb. Each pollutant has a specific concentration range and corresponding AQI value. The AQI ranges from 0 to 500, with higher values indicating greater levels of air pollution and associated health risks. The AQI is divided into several categories, each with its own color code, to make it easier for the public to understand the severity of air pollution.
Indian CPCB AQI Categories and Ranges
The Indian CPCB has established six primary AQI categories, each with a specific range and color code. These categories help the public understand the current air quality and the associated health implications.
- Good (0-50, Green): Air quality is considered satisfactory and poses little or no risk to health. This is the ideal range for outdoor activities and breathing.
- Satisfactory (51-100, Light Green): Air quality is acceptable; however, there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution. Most people can continue their normal activities.
- Moderate (101-200, Yellow): Air quality is acceptable; however, some pollutants may cause moderate health concerns for a larger number of people. Sensitive groups, such as children, older adults, and those with respiratory conditions, should consider reducing prolonged outdoor activities.
- Poor (201-300, Orange): Air quality is unhealthy for sensitive groups. Members of sensitive groups may experience health effects, while the general public is less likely to be affected. Outdoor exercise should be limited, and those with respiratory conditions should stay indoors as much as possible.
- Very Poor (301-400, Red): Air quality is unhealthy for all groups. Everyone may begin to experience health effects, and sensitive groups may experience more serious effects. It is recommended to use how to protect children from air pollution measures such as wearing masks and using air purifiers.
- Severe (401-500, Maroon): Air quality is hazardous, and health warnings of emergency conditions are in place. Everyone is likely to be affected, and sensitive groups should avoid all outdoor activities. It is crucial to stay indoors and use air purifiers to reduce exposure to pollutants.
Health Implications of AQI Levels
The health effects of air pollution vary depending on the AQI level and the individual's sensitivity to pollutants. According to the World Health Organization (WHO), even moderate levels of air pollution can have adverse health effects, particularly for sensitive groups. At higher AQI levels, the risk of respiratory and cardiovascular issues increases significantly.
At Good and Satisfactory levels, the air quality is generally safe for most people. However, as the AQI moves into the Moderate range, sensitive groups may experience mild symptoms such as coughing or shortness of breath. When the AQI is Poor or Very Poor, sensitive groups and the general public may experience more severe symptoms, including aggravated asthma, respiratory infections, and decreased lung function. At the Severe level, the risk of serious health effects is high, and immediate action should be taken to minimize exposure.
Actions to Take at Each AQI Level
Understanding the AQI level is crucial for taking appropriate actions to protect your health. Here are some general guidelines for each category:
- Good (0-50): Enjoy outdoor activities without restrictions.
- Satisfactory (51-100): Most people can continue normal activities, but sensitive groups should monitor their symptoms.
- Moderate (101-200): Sensitive groups should reduce prolonged outdoor activities and consider wearing masks. The general public can continue activities but should be mindful of symptoms.
- Poor (201-300): Sensitive groups should avoid outdoor exercise and stay indoors as much as possible. The general public should limit outdoor activities and consider using air purifiers.
- Very Poor (301-400): Everyone should avoid outdoor exercise and minimize outdoor activities. Sensitive groups should stay indoors and use air purifiers. Wearing masks is recommended when outdoor exposure is unavoidable.
- Severe (401-500): Everyone should stay indoors and avoid all outdoor activities. Use air purifiers to maintain indoor air quality and wear masks if outdoor exposure is necessary.
Comparison with US EPA AQI Categories
While the Indian CPCB and US EPA both use the AQI to communicate air quality, there are some differences in the categories and ranges. The US EPA AQI scale includes the following categories:
- Good (0-50): Same as CPCB.
- Moderate (51-100): Similar to CPCB's Satisfactory.
- Unhealthy for Sensitive Groups (101-150): Comparable to CPCB's Moderate.
- Unhealthy (151-200): Similar to CPCB's Poor.
- Very Unhealthy (201-300): Comparable to CPCB's Very Poor.
- Hazardous (301-500): Similar to CPCB's Severe.
It's important to note that the US EPA's live AQI by city may have different implications for health and recommended actions due to variations in pollutant concentrations and local health guidelines.
Key takeaways
- The AQI is a vital tool for understanding air quality and its impact on health.
- The Indian CPCB categorizes AQI into six levels, each with specific health implications and recommended actions.
- Sensitive groups, including children, older adults, and those with respiratory conditions, should take extra precautions at higher AQI levels.
- At what the AQI number means, it's crucial to adjust outdoor activities and take protective measures to minimize exposure to pollutants.
- Comparing the CPCB and US EPA AQI scales highlights the importance of understanding local air quality standards and guidelines.
By staying informed about the AQI and its categories, you can make informed decisions to protect your health and well-being.
The six AQI categories (India CPCB scale)
| AQI | Category | Associated health impact |
|---|---|---|
| 0–50 | Good | Air quality is considered satisfactory and air pollution poses little or no risk. |
| 51–100 | Satisfactory | Acceptable air quality; minor breathing discomfort possible for unusually sensitive people. |
| 101–200 | Moderate | May cause breathing discomfort to people with lung disease such as asthma, and to children and older adults. |
| 201–300 | Poor | May cause breathing discomfort to most people on prolonged exposure. |
| 301–400 | Very Poor | May cause respiratory illness on prolonged exposure; effects more pronounced for people with lung and heart disease. |
| 401–500 | Severe | Affects healthy people and seriously impacts those with existing diseases; avoid outdoor activity. |
Frequently asked questions
What are the AQI levels?
India's AQI has six levels: Good (0–50), Satisfactory (51–100), Moderate (101–200), Poor (201–300), Very Poor (301–400) and Severe (401–500).
What are the AQI colour codes?
Good is green, Satisfactory light green, Moderate yellow, Poor orange, Very Poor red and Severe dark maroon.
What AQI level is unhealthy?
Above 100 the air begins to affect sensitive groups; above 200 ("Poor") it affects most people on prolonged exposure; above 300 it affects everyone.
What is the highest AQI category?
"Severe" (401–500) is the worst category — it affects healthy people and seriously harms those with existing heart or lung disease.
What AQI is safe for outdoor exercise?
An AQI under 100 is generally fine for outdoor exercise. Sensitive groups should be cautious above 100, and everyone should move workouts indoors above 200.