NEW DELHI: Data released by the Central Pollution Control Board (CPCB) on Saturday showed air pollution levels in 2015 were higher than the two previous years at most its monitoring stations. On the contrary, figures released by the Delhi Pollution Control Committee (DPCC) showed a decline in PM 2.5 (fine, respirable pollution particles) concentrations in 2015.
CPCB scientists, however, advised against reading too much into the trends because they continue to use manually-operated stations whereas DPCC has automatic stations. CPCB's data also indicates that levels of nitrogen dioxide (NO2) have fallen in three out of six locations in 2015 compared with 2014, but PM 2.5 levels spiked at all locations compared with 2014.
The highest jump was seen in Pitampura and Shahdara. In Pitampura, the level increased from an annual average of 89 micrograms per cubic metres to 119 micrograms per cubic metres in 2015 while in Shahdara, it rose from 85 to 113 micrograms per cubic metres.
"I don't think we can conclude that the air quality is worsening on a year-on-year basis because meteorological factors often influence them. We are yet to conduct a five-year review to see the trends. Also, there should be continuous actions against air pollution to see a real change in the annual trends," said a CPCB scientist.
DPCC's annual average for their six automatic stations shows a sudden fall in 2015. However, the annual average for six manual monitoring stations by DPCC indicates a gradual increase from 73 micrograms per cubic metres in 2013 to 80 in 2014 and 100 in 2015.
"DPCC has submitted a report to the high court, which shows PM 2.5 levels to be higher than what CPCB claims. But there is also a declining trend in 2015. Manual monitoring stations show lower levels, which could lead to underestimation of the problem," said Anumita Roy Chowdhury, head CSE's clean air campaign.
The World Health Organization's (WHO) urban air quality database released on May 12 ranked the capital 11th among 3,000 polluted cities. In 2014, WHO had declared Delhi as the most polluted city , with a mean annual PM2.5 level of 153 gm3.That number has come down to 122 in the latest report.