Context:
The Air Quality Index of Mumbai is worse than Delhi.
About AQI:
- Air Quality Index is a tool for effective communication of air quality status to people in terms, that are easy to understand.
- It transforms complex air quality data of various pollutants into a single number (index value), nomenclature and colour.
- 6 AQI categories – Good, Satisfactory, Moderately polluted, Poor, Very Poor, and Severe.
- Each of these categories is decided based on ambient concentration values of air pollutants and their likely health impacts (known as health breakpoints).
- AQ sub-index and health breakpoints are evolved for 8 pollutants (PM10, PM2.5, NO2, SO2, CO, O3, NH3, and Pb) for which short-term (up to 24-hours) National Ambient Air Quality Standards are prescribed.
- The worst sub-index determines the overall AQI. AQI categories and health breakpoints for the 8 pollutants are as follow:
How is AQI calculated?
- The Sub-indices for individual pollutants at a monitoring location are calculated using its 24-hourly average concentration value (8-hourly in case of CO and O3) and health breakpoint concentration range. The worst sub-index is the AQI for that location.
- All the 8 pollutants may not be monitored at all the locations. Overall AQI is calculated only if data are available for minimum 3 pollutants out of which one should necessarily be either PM2.5 or PM10. Else, data are considered insufficient for calculating AQI.
- A minimum of 16 hours’ data is considered necessary for calculating sub index.
SAFAR
- SAFAR – System of Air Quality and Weather Forecasting and Research
- Objective:
- To provide location-specific information on air quality in near real time and its forecast 1-3 days in advance for the first time in India.
- It has been combined with the early warning system on weather parameters.
- Initiative by Ministry of Earth Sciences (MoES)
- Developed by Indian Institute of Tropical Meteorology, Pune, along with ESSO partner institutions namely India Meteorological Department (IMD) and National Centre for Medium Range Weather Forecasting (NCMRWF)
- For greater metropolitan cities of India
Source: The Indian Express
Previous year question
In the context of WHO Air Quality Guidelines, consider the following statements:
1. The 24-hour mean of PM2.5 should not exceed 15 µg/m³ and annual mean of PM2.5 should not exceed 5 µg/m3.
2. In a year, the highest levels of ozone pollution occur during the periods of inclement weather.
3. PM10 can penetrate the lung barrier and enter the bloodstream.
4. Excessive ozone in the air can trigger asthma.
Which of the statements given above are correct? [UPSC Civil Services Exam – 2022 Prelims]
(a) 1, 3 and 4
(b) 1 and 4 only
(c) 2, 3 and 4
(d) 1 and 2 only
Answer: (b)
In the cities of our country, which among the following atmospheric gases are normally considered in calculating the value of Air Quality Index?
1. Carbon dioxide
2. Carbon monoxide
3. Nitrogen dioxide
4. Sulfur dioxide
5. Methane
Select the correct answer using the code given below. [UPSC Civil Services Exam – 2016 Prelims]
(a) 1, 2 and 3 only
(b) 2, 3 and 4 only
(c) 1, 4 and 5 only
(d) 1, 2, 3, 4 and 5
Answer: (b)
