Air Pollution

Various sources are responsible for air pollution. The natural sources are forest fires, volcanic eruptions, bacterial decomposition of organic matters etc. Operation of industrial processes, burning of fuel for heating and cooking in households, plying of fuel-driven vehicles, use of explosives for mining and in warfare etc are anthropogenic sources of air pollution. The air pollutants may be either Primary or Secondary.

The primary pollutants are those which are directly released into the atmosphere and the secondary pollutants are products of atmospheric reactions of the main primary pollutants. Products of combustion – both complete and incomplete – of fossil fuels are the main primary pollutants released into the atmosphere. These include Carbon dioxide, carbon monoxide, sulphur dioxide, oxides of nitrogen and unburnt hydrocarbons. Carbon monoxide and carbon dioxide are products of oxidation of carbon. Sulphur dioxide comes from the burning of sulphur which is invariably present in coal and oil. Oxides of Nitrogen (NOx), is the product of high temperature combustion of fuel such as the one taking place inside internal combustion engines and even, to some extent, in thermal power plats. Besides the products of combustion of fossil fuels, primary pollutants also include suspended particulate matters (SPM) generated in various activities and other gases or vapours produced in specific industrial and natural processes e.g. ammonia, chlorine, chlorofluoro carbon, solvent vapours etc. A large variety of organic and inorganic compounds like aldehydes, ketones, acids, nitrates, epoxides and peroxyacetyl nitrate (PAN) present in the atmosphere in extremely low quantities, are considered as secondary pollutants. The well known meteorological phenomena associated with air pollution – the Acid Rain and the Photochemical Smog formation – are attributed to secondary pollutants formed atmospheric reactions.

Air pollution has become very serious in urban areas, mainly due to automobile exhausts, industrial emissions and construction works.

The State Pollution Control Board (SPCB) is entrusted with the direct implementation of the provisions of the Air Act, 1981 to prevent, control and abate air pollution in the State. National Ambient Air Quality Monitoring network was initiated by Central Pollution Control Board (CPCB) in 1984. In Odisha; 8 NAAQM stations have been established in different phases. Monitoring is being conducted in all eight stations. Board has also established a State Ambient Air Quality Monitoring Network (SAAQM). At present SAAQM network has 8 monitoring stations. The monitoring stations have been located in different areas viz. Residential or rural as well as commercial.

How is AQI calculated?

1. 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.

2. All the eight pollutants may not be monitored at all the locations. Overall AQI is calculated only if data are available for minimum three pollutants out of which one should necessarily be either PM2.5 or PM10. Else, data are considered insufficient for calculating AQI. Similarly, a minimum of 16 hours’ data is considered necessary for calculating subindex.

3. The sub-indices for monitored pollutants are calculated and disseminated, even if data are inadequate for determining AQI. The Individual pollutant-wise sub-index will provide air quality status for that pollutant.

4. The web-based system is designed to provide AQI on real time basis. It is an automated system that captures data from continuous monitoring stations without human intervention, and displays AQI based on running average values (e.g. AQI at 6am on a day will incorporate data from 6am on previous day to the current day).

5. For manual monitoring stations, an AQI calculator is developed wherein data can be fed manually to get AQI value

Source- CPCB Website

Source- CPCB Website

Source- CPCB Website