NEW DELHI: An experimental station being run by the Central Pollution Control Board to monitor some toxic trace gases shows the capital's air doesn't just have very high particulate matter levels, but is also laced with hazardous air pollutants, such as mercury and formaldehyde. But it's too early to say if the levels being recorded at this experimental station are too high, simply because there are no standards in India for these air toxics yet. Experts, however, say they are dangerous even at "trace" levels.
CPCB had set up a continuous air quality monitoring station based on Differential Optical absorption Spectroscopy (DOAS) at PariveshBhawan, East Arjun Nagar. It released data from the station from 2011 to 2016 in a draft report recently.
'The station monitors sulphur dioxide (SO2), ozone (O3), nitric oxide (NO), nitrogen dioxide (NO2), formaldehyde (FOR), benzene (BEN), toluene (TOL), p-Xylene(pXy) and mercury (Hg), most of which are categorised as air toxics in the US and in Europe. These are mainly gases, particles or aerosols present in the air at levels where they pose a hazard to human health and they include volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), heavy metals and aldehydes.
CPCB started monitoring them on an experimental basis to study whether the same technology can be used to monitor emissions at critically polluted areas like industrial clusters, thermal power plants or around, say, pesticide manufacturing units. Among the air toxins monitored here, there are safe standards set for both benzene and ozone—while O3 levels met the annual standard, the standard for benzene was breached in all years except 2016.
Unlike the US environment protection agency (EPA), India doesn't have an air toxics programme. According to US EPA, these pollutants are known or suspected to cause cancer or other serious health effects, such as reproductive effects or birth defects, or adverse environmental effects which is why EPA monitors 187 such air toxics. They regulate air toxics from large industrial facilities as well as smaller sources.
On what could be the source for mercury or toluene being recorded by the CPCB station, DipankarSaha, former head of CPCB air lab, said: "This is an experimental station. Scientists are still trying to understand and validate the data. The only reason this station was set up was because we wanted to see if the technology can be used for critically polluted areas without any difficulty."
CPCB has, however, not started monitoring these hazardous air pollutants on a large scale despite their serious health implications. "We have been saying that India needs a separate air toxics programme because these are pollutants, which will have to be eliminated from air, they are carcinogens. The monitoring should be done in a more widespread manner on a long-term basis," said AnumitaRoychowdhury, executive director at the Centre for Science and Environment.
