It’s not even Diwali, and a toxic haze has already covered Mumbai. Vaishnavi Chandrashekhar spoke to IIT Bombay environmental scientist Abhishek Chakraborty about what’s behind the early pollution and whether govt’s measures will help.
Because of climate change, but one thing that’s been happening pan-India is that wind speeds have been slowing, partly. Because mumbai has good sunlight and humidity, which are both conducive to producing secondary pollutants, chemistry has never been in our favour. Mumbai saw a spike in air pollution levels last week, with visible haze. What do you think is happening? With a few days or even a week of haze, we can’t be sure. Maybe the wind came from a direction that had a lot of pollution. This means mixing of air is getting less efficient, leading to more accumulation of pollution. Some studies indicate a slowdown is also happening in Mumbai’s sea breeze. So its effectiveness in reducing pollution could be declining. There are three components influencing pollution: emission, meteorology, and chemistry. Mumbai has high emissions, but the meteorology used to be in our favour. It was only meteorology that saved us, and now that is getting weakened. I suspect that untimely haze events are going to increase in the future. Warmer temperatures can also accelerate some of the atmospheric reactions involved in the formation of ground-level ozone and secondary particulates. How do sunlight and humidity influence pollution? Emissions have increased, of course, and construction is part of that. Construction activity contributes a lot of coarse particles, which can increase pollution load and reduce visibility. These particles can also contribute to secondary particulate formation. Last week, we saw official air monitors record lower pollution levels compared with independent platforms like IQAIR.
Regulatory bodies like CPCB and MPCB use instruments that are the gold standard for air quality measurement, compared with the low-cost sensors and satellite data that these groups use. But there are many factors that affect the results of reference-grade monitors: Are they being calibrated properly? Are they relaying data correctly?