Air Quality Index (AQI)


The World Health Organization (WHO) and US-EPA are widely recognized all over the globe as general guideline book for providing the general air quality index and standards. But the ambient air quality standard and break points vary from one country to another, the first step is to come up with country specific NAAQS which the Ministry of Environment and Forest (MoEF), Govt of India has released and updated in 2009 for India. However, concept of AQI was not available for India. Scientists of Ministry of Earth Sciences (MoES) from IITM, Pune came up with the concept of AQI in India for the first time after extensive research and collecting and analysing Health data and published a technical scientific report (AQI Report, SAFAR-2010B, MoES, GoI, 2010). This has provided yet another milestone in India’s Air Quality management history.

The AQI has been developed to provide advice on expected levels of air pollution. In addition, information on the short-term effects on health that might be expected to occur at the different bands of the index (Good, Moderate, Poor, Very Poor and Critical) is provided. It is expected that the vulnerable people, children and asthmatic people may experience health effects even on Low air pollution days (long-term). This advice applies to anyone experiencing symptoms. The purpose of the AQI is to help you understand what local air quality means to your health. The value of AQI corresponds to concentration of the specific pollutant present in the air at the time of measurement. Different AQI values are generated for various pollutants. To make it easier to understand, the AQI is divided into colour bands as shown in the figure below.Air pollution has a range of effects on health. It will be interesting to know the air pollution levels at which people need to make major changes to their living habits to avoid exposure. However, nobody needs to fear going outdoors to perform their routine activities. Severity of the presence of air pollutant depends on its concentration in the air. AQI value represents the concentration of pollutant in the air. AQI level can be interpreted for health impact as:

Figure: Different categories of AQI shown in different colours and associated impacts.

Air Quality Index and related Health Advisory:

For Gaseous/Particulate pollution: (Whichever is more)

Pollution Range of Air Quality Index (AQI) Effect Health advisory
1) 0 to 100 Good Air quality is satisfactory, and air pollution poses little or no risk
2) 101 to 200 Moderate Air quality is acceptable; however, there may be a moderate health concern for people sensitive to air pollution.
3) 201 to 300 Poor Sensitive people may experience health effects. The general public is less likely to be affected.
4) 301 to 400 Very Poor It triggers health alert everyone may experience more or less health effects, avoid outdoor activity. It is advisable to use pollution masks
5) 401 Onwards Critical It is Health warning of emergency conditions, immediate precautionary measures are required