Smog smothers city, relief by Sunday

A mixture of fog and air pollutants, the haze is not as innocent as it looks. It is, in fact, a silent killer for those suffering from cardiac troubles and asthmatic patients. Some countries even have a smog level alert system where such `vulnerable people’ are asked not to venture out of their homes. In Delhi, though a common feature every winter, no such watch is kept as yet.

The most immediate effects are burning sensation in the eyes, throat irritation and exhaustion felt by all residents in all areas of the city.

According to Dilip Biswas, chairman, Central Pollution Control Board (CPCB), the pollution is not the only criminal, the proof being that despite a lesser number vehicles on the road on Wednesday which was a holiday, smog had formed in the city.

However, the pollution figures show an increase as the `mixing height’ of the pollutants becomes as low as 200 m as compared to 1,000 m in summers enabling pollutants to disperse easily in the atmosphere.

Because of the high levels of Suspended Particulate Matter (SPM) in the city’s air, which is way above the prescribed norms, the mist turns into smog. Normally it is above 700 microgram/cubic metre as against 500 microgram/cubic metre the prescribed norm. During these days, it increases at least three times, according to environmentalists.

The other reason for the smog is a phenomenon known as `subsidence’. Because of prevailing pressure patterns, pollutants which should go up settle at lower levels explaining the `blanket’ which forces commuters to switch on their headlights even during daytime.

How accurate are the pollution board’s estimates. As the pollutants are “locked in the breathing zone”, it is important for it to be measured at that level. But CPCB has monitoring equipment placed on rooftops of buildings which does not give the accurate picture in these situations.

High-rise buildings act as blockades preventing the pollutants from dispersing. It is heavier in areas where the traffic movement is heavy or where there are industries.

According to the meteorological department, the frequency of the smog has not changed over the years. The pollution problem is aggravated because of weather conditions.

A spell of rain which is expected in the next few days will get the pollutants to settle. The situation is fast moving in that direction with medium high clouds at a height between 2,000 and 3,000 feet forming over the city.