An Air Quality Index (AQI) is a number used by government agencies to measure the air pollution levels and communicate it to the population. As the AQI increases, it means that a large percentage of the population will experience severe adverse health effects. The measurement of the AQI requires an air monitor and an air pollutant concentration over a specified averaging period. The results are grouped into ranges, and each range is assigned a descriptor, a color code and a standardized public health advisory.

Historically, all continents have been using the AQI established by the United States Environmental Protection Agency (EPA), which is a piecewise linear function of the pollutant concentration. If multiple pollutants are measured at a monitoring site, then the biggest AQI value in one hour average is reported for that location. However, air pollution in each country is very much specific to the country pollution type.

Air Quality Index in India

The pollution sources in India – and in most asian countries – are numerous and incompletely understood. In Delhi, for example, it comes mostly from light and heavy duty vehicle traffic emissions, road dust, solid fuel combustion for heating and cooking, biomass, waste burning, thermal power plants, diesel generators, construction and small-scale local industries. That’s why each country has to have their own AQI values.

The National Air Quality Index Standard (NAQI) in India was launched by The Minister for Environment, Forests & Climate Change, Shri Prakash Javadekar, on 17 September 2014. The initiative constitutes part of the Government’s mission to introduce the “culture of cleanliness”, as the air pollution has been a huge concern in the country, especially in urban areas. The National Air Monitoring Program (NAMP), that covers 240 cities in the country, has been operated by the  Central Pollution Control Board (CPCB) and developed by the Indian Institute of Technology, Kanpur (IIT), providing data in public domain, on real time basis. You can access it by clicking here.

To understand how the AQI works, you just have to know the six range categories (Good, Satisfactory, Moderately Polluted, Poor, Very Poor, and Severe) and check the associated health impacts. Solutions should be taken based on the AQI Category and the pollutant associated to it, as follows:

 

AQI categories and breakpoint concentrations with averaging times

(units: µg/m3 unless mentioned otherwise)

AQI Category (Range) PM10 (24hr) PM2.5 (24hr) NO2 (24hr) O3 (8hr) CO (8hr) SO2 (24hr) NH3 (24hr)

Pb (24hr)

Good (0-50)

0-50 0-30 0-40 0-50 0-1.0 0-40 0-200 0-0.5

Satisfactory (51-100)

51-100 31-60 41-80 51-100 1.1-2.0 41-80 201-400 0.5-1.0
Moderately polluted (101-200) 101-250 61-90 81-180 101-168 2.1-10 81-380 401-800

1.1-2.0

Poor (201-300) 251-350 91-120 181-280 169-208 10-17 381-800 801-1200

2.1-3.0

Very poor (301-400) 351-430 121-250 281-400 209-748 17-34 801-1600 1200-1800

3.1-3.5

Severe (401-500) 430+ 250+ 400+ 748+ 34+ 1600+ 1800+

3.5+

 

AQI: Health Impacts

AQI

Associated Health Impacts

Good (0-50)

Minimal impact

Satisfactory (51-100)

May cause minor breathing discomfort to sensitive people.

Moderately polluted (101–200)

May cause breathing discomfort to people with lung disease such as asthma, and discomfort to people with heart disease, children and older adults.

Poor (201-300)

May cause breathing discomfort to people on prolonged exposure, and discomfort to people with heart disease.
Very poor (301-400)

May cause respiratory illness to the people on prolonged exposure. Effect may be more pronounced in people with lung and heart diseases.

Severe (401-500)

May cause respiratory impact even on healthy people, and serious health impacts on people with lung/heart disease. The health impacts may be experienced even during light physical activity.

If you check the Indian NAQI, you are gonna realize that the Particulate Matter (PM) pollution ranks is the worst among the other pollutants. Compared to the other countries, ambient fine particulate matter (PM2.5) levels in Delhi rank among the highest levels measured in any city in the world: about 15 times higher than the World Health Organization (WHO) guideline concentrations. This means that several interventions to change this scenario must be taken by the government and the local population, otherwise we’re gonna still be facing a lot of health and environmental implications due to air pollution. Seems like building awareness is the best way to start.