Warmer winter is cleaner too

The absence of real chill in what turned out to be one of the warmest winters in 107 years meant Delhiites breathed cleaner air than is usual in the winter months, according to Central Pollution Control Board (CPCB) data, reports Avishek G Dastidar.

The absence of real chill in what turned out to be one of the warmest winters in 107 years meant Delhiites breathed cleaner air than is usual in the winter months, according to Central Pollution Control Board (CPCB) data.

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The levels of toxic nitrogen oxide (NOx) in air samples at all the continuous monitoring stations of the CPCB in Delhi in December and January saw a considerable drop compared with the same period in the past two years.

On the other hand, at various places the levels of tiny harmful particles suspended in the air either went down or remained almost the same as the past two winters.

At the Siri Fort monitoring station, there were only six days in the past two months when the level of NOx breached the prescribed standard — as opposed to 46 days in the same period in 2007-08 and 53 days in 2006-07. The average concentration saw a drop from 133 micrograms per cubic meter (ug/m3) last winter to 43 ug/m3 this time.

The average concentration of dust levels in December and January dropped to 273 ug/m3 — a fall from 306 ug/m3 last winter recorded at the monitoring station at the Delhi College of Engineering.

At ITO, the level of particulate matter remained unchanged, while NOx concentration during the past two months saw a 50 per cent drop from the corresponding period in the previous year.