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The Air Quality Index (AQI) is an index for reporting air quality on a daily basis. It measures air pollution affects one's health within a short time period. The purpose of the AQI is to help people know how the local air quality impacts their health.

As per the Environmental Protection Agency (EPA) the AQI is calculated for five major air pollutants: 
  • Ground-level ozone
  • Particle pollution/particulate matter (PM2.5/pm 10)
  • Carbon Monoxide
  • Sulfur dioxide
  • Nitrogen dioxide

The higher the AQI value, the more level of air pollution and greater impacts on health. The concept of AQI has been widely used in many developed countries for over the last three decades. AQI quickly disseminates air quality information in real-time.

AQI is calculated differently in various countries by using different point scales to report air quality. India follows the 500 point scale wherein rating between 0 and 50 is considered good. Rating between 301 to 500 range is deemed hazardous. The monitoring is done daily and concentrations of the major pollutants are recorded daily. These raw measurements are converted into a separate AQI value for each pollutant (ground-level ozone, particle pollution, carbon monoxide, and sulfur dioxide) using standard formulae developed by EPA.

The highest of these AQI values are reported as the AQI value for that day. The Air Quality Index categories are as under:

·         Good (0–50) - Minimal Impact

·         Satisfactory (51–100) - May cause minor breathing difficulties in sensitive people.

·         Moderately polluted (101–200) - May cause breathing difficulties in people with lung disease like asthma, and discomfort to people with heart disease, children and older adults.

 ·         Poor (201–300) - May cause breathing difficulties in people on prolonged exposure, and discomfort to people with heart disease

 ·         Very Poor (301–400) - May cause respiratory illness in people on prolonged exposure. Effect may be more pronounced in people with lung and heart diseases.

 ·         Severe (401-500) - May cause respiratory issues in healthy people, and serious health issues in people with lung/heart disease. Difficulties may be experienced even during light physical activity.

Objectives of Air Quality Index (AQI)
  • Comparing air quality conditions at different locations/cities.
  • It also helps in identifying faulty standards and inadequate monitoring programmes.
  • AQI helps in analysing the change in air quality (improvement or degradation).
  • AQI informs the public about environmental conditions. It is especially useful for people suffering from illnesses aggravated or caused by air pollution.

Status of Air Quality Index in Punjab

Source: Punjab Pollution Control Board, 2019