Rakesh Kumar, chief scientist at the National Environment Engineering Research Institute (NEERI), Worli, spoke to HT about the chief sources of pollution in Mumbai.
Which pollutants affect human health the most?
Of course PM2.5, as they are fine particles and can enter our bodies through the normal breathing systems. Finer than PM 2.5 is PM 1, which can seep further into the lungs, passing through our natural filtration process.
What are the sources of pollutants such as particulate matter, oxides of nitrogen, sulphur dioxide and carbon monoxide?
Pollutants have multiple sources. In a larger area, fine particles come from combustive processes including the burning of fuel, garbage and wood. Construction dust from road surfacing work involving cement and coal-tar also disperses across the city.
How will the Air Quality Index help a city like Mumbai?
It is definitely useful and a step in the right direction. There are various sources naturally present in the air that cannot be controlled. These natural pollutants also make up part of a city’s air quality. Delhi has a larger number of natural sources of dust with respect to controlled pollutant particles, than Mumbai. In Mumbai, the sea breeze takes majority of the natural sources away. Thus, the Air Quality Index will be an indicator of our pollution-related issues.
What is the key problem that gives rise to high pollution levels in Mumbai?
The biggest problem in Mumbai is congestion. Along with narrow roads, there are scores of vehicles crammed in every part of the city. With green lungs depleting, construction and paving of roads are primary sources. Dumper trucks travelling in the city are another important source of air pollution.
What is the correlation between weather and pollution?
It is a complex phenomenon. The amount of pollutants in the air is less during the monsoon – when rain droplets mix with smaller dust particles and make them settle on the ground. Pollution also incorporates factors such as temperature, wind and sunlight. If there is no wind and sunlight is very bright, pollution levels are high. If there is a constant flow of wind but no moisture, pollutant particles will stagnate in the air, pushing up pollution levels.