Study hints at bias in the country’s air pollution monitoring
SHORTCOMING The report said that there was no meta data or quality control data available for public scrutiny.
India’s network of manual and real-time (automatic) air pollution monitoring stations is resulting in an information bias and may not be giving a representative picture for health epidemiology studies, a new study done by US and Indian scientists this year revealed.
Currently, India has one air pollution monitoring station for every two million people. It has more manual than real time monitoring stations. The real-time stations are concentrated in north India, some western and southern states — Delhi, Uttar Pradesh, Rajasthan, Maharashtra, Telangana — but there is no real-time data reporting from central states — Chhattisgarh, Jharkhand, Odisha — that have a heavy burden of polluting industries and mines. There are no real-time stations in the northeastern states either.
The report — ‘Monitoring Particulate Matter in India: Recent Trends and Future Outlook’ — to be published shortly, has mapped manual air pollution monitoring stations under the National Air Quality Monitoring Programme (NAMP) based on population density, and found that air pollution dataset from India mainly represents urban and peri-urban areas. Lack of data from rural areas may also be contributing to exposure misrepresentation, the study found.
While urban bias in such monitoring is known, the report has raised questions about data quality from manual monitoring stations and discussed trends in PM 10 (coarse pollution particles) concentrations from 2004 to 2015 from the NAMP.
NEW DELHI:
MANUAL VERSUS AUTOMATIC STATIONS
There are 683 manual air quality stations in 300 cities and towns and a network of 87 continuous automatic air quality monitoring stations (CAAQMS) that provide data in real time from 52 cities in only 15 states, the report found.
The manual stations in India collect samples over eight-hour spans typically twice a week, which may not provide representative air quality status. Manual monitoring also results in delay in data collection and has a large error margin and variation. Manual stations should pick up data for at least 104 days a year, but at most stations, data was captured for fewer days than required. The report added that there was no meta data or quality control data available for public scrutiny.
A senior Central Pollution Control Board (CPCB) official said the number of stations has increased marginally since this study was conducted.
0.23% OF PM 10 TRENDS MEET ‘WHO’ STANDARDS
The study also assessed PM 10 concentration trends from 683 NAMP stations between 2004 and 2015 to find only 0.23% annual averages met the annual World Health Organisation (WHO) guideline and about 19% met the Indian annual standard.
In 12 years, only one station at Tekka Bench Ridge in Shimla met the WHO standard twice — in 2004 and 2005.
Sarora in Chhatisgarh recorded the highest PM 10 concentrations in 2011, but Delhi has consistently been the most polluted state since 2008. PM 10 concentrations were the highest in northern India — Uttar Pradesh, Delhi, Jharkhand, Punjab and Rajasthan.
GOOD REAL-TIME NETWORK MAY COST A LOT
The report recommends increasing funding to improve data collection. Speciation data of particulate matter (chemical composition of PM) will be more useful as that will help target specific sources of pollution.
The CPCB plans to set up realtime stations by 2020. Average cost of a real-time station is ~1 crore.