Weather, bldg work worsen smog in city

Mumbai: Mumbai's weather has gone from pleasantly cold to stiflingly hot in a matter of days, but the smog that continues to envelop the city is an indicator of the poison Mumbaikars have been inhaling. The weather, along with the city's congested roads and constant 

construction activity, had resulted in pollution levels increasing three-fold over the standard acceptable limits last week. 
    According to the Mumbai Pollution Control Board, pollution levels—particularly nitrogen oxide (NOx) and suspended particulate matter (SPM) — have been exceptionally high in the past few days. While the pollution levels in January were more than double the accepted limits, they have further worsened in February. 
    On February 1, SPM levels rose to as high as 342 micrograms per cubic metre. On February 6, the levels were 335 micrograms per cubic metre. NOx levels were also high at 178 micrograms per cubic metre on February 7. "Anything above 100 micrograms of SPM and 80 micrograms of NOx in a cubic metre of air is bad for human health," said an MPCB official. He added that in certain parts of the city, pollution levels were perennially higher than the standard limits. Traffic congestion compounds weather woes Pollution Levels In City Increase Three-Fold Over Normal Level in February Due To Fluctuating Mercury, Construction Work 
    Blame the weather, the traffic and the city's unceasing construction work for the foul air you breathe. 
    "When the weather gets cooler, SPM levels tend to rise because of inversion," said Dr Rakesh Kumar of the National Environment Engineering Research Institute. 
    Normally, the air near the earth's surface is warmer than that in the upper atmosphere. During inversion, however, there is cold air near the surface, which gets trapped under the warmer air. "At such a time, hot and cold air don't mix easily in the upper atmosphere. Because of this, pollutants get trapped in the lower atmosphere," explained Dr Kumar. 
    Last week, however, the weather had been consistently warm. What's more, extremely high pollution levels were recorded at the Sion air quality station of MPCB. 
    The figures recorded at Bandra air quality station, though high, were not as alarming. 
    Dr Kumar has a possible explanation for this too. "Strong winds break inversion and blow away pollutants. Since Bandra has a sea face, the pollutants are occasionally blown away. But Sion is not so fortunate, hence pollution levels there are higher." 
    However, a mere fluctuation in mercury levels is not the only cause of Mumbai's poor air quality, said experts, pointing out that increasing vehicular density and construction pollution are equally to blame. 
    "Pollution norms for vehicles may be in place, but their sheer numbers in Mumbai override the norms and lend to the addition in SPM levels," said Dr Neelam Rane, professor of physiology at D Y Patil Medical College. 
    Dr Rohini Chowgule, from the Indian Institute of Environmental Medicine (IIEM), said that 100 micrograms per cubic metre is actually a standard limit for industrial areas. 
    "The limit for normal breathing air in a residential area is much lower. Human actions like burning grass to make soil more fertile, apart from traffic and construction activity, are causing pollution levels to rise exceptionally high," she said. 
    "Moreover, vehicles emit more pollution when moving slowly. In Mumbai, the problem gets amplified due to the bumper-to-bumper traffic. Also, there is always some construction, renovation or restoration work happening, which is an even greater source of pollution," added Dr Rane.