The government is looking to prepare a unified testing methodology to ensure that all agencies that map air pollution use accurate instruments.
The Council of Scientific and Industrial Research (CSIR) -National Physical Laboratory (NPL) is in the process of setting up ‘gas standards’, or reference samples of Carbon Monoxide (CO), Sulphur Dioxide (SO2), Nitrous Oxide (NO2) and Particulate –Pb (lead), –As (Arsenic) and –Ni (Nickel).
Currently, the National Ambient Air Quality standards specify the upper limits for pollutants and, based on this, the Air Quality Index — that grades air quality in cities from ‘Good’ to ‘Severe’ — is prepared for several Indian cities.
Devices not calibrated
“However we have noticed several times that these measurement devices are not calibrated and errors creep in,” said D.K. Aswal, Director, National Physical Laboratory. “This month, we are ready with the standards for several pollutants.”
Going ahead, he said, there would be talks with environment-monitoring agencies like the the Central Pollution Control Board (CPCB) to see if these can become reference standards for use by all private and public agencies that measure pollution levels.
CPCB has prescribed guidelines for the maximum permissible levels of 12 gases and pollutants, depending on residential, rural or industrial locations. Standards for PM2.5 were laid out in 2009, though CPCB is now mooting a proposal to revise these standards, a senior official in the organisation hadtold The Hindu earlier this year.
The NPL has also developed a custom air sampler that claims to measure PM2.5 levels far more accurately than existing devices.