CHENNAI: For a short period of time when the city woke up to heavy smog, air pollution became a concern. Is it any better now? A new study has shown that the city’s IT corridor is a pollution hotspot, and people inhale high concentrations of pollutants all the time. The study, conducted by IIT-Madras, compares personal exposure to air pollution at sidewalks along the IT corridor and the Marina beach promenade. Multiple measurements were made for a period of 10 days. The results, experts say, were startling.
Pedestrians waiting near the corridors and traffic intersections are exposed to high pollutant concentrations. Along the IT corridor, the PM concentrations exceed the permissible levels most of the time by a probability of 40-100%. This means, there is significant contribution to pollution by local sources.
“There is a 30-100% probability of exceeding the critical PM2.5 concentration during the morning as compared to 10-22% probability during the evening. At beach promenade, the probability was found to be highly variable. During the morning the probability of exceeding permissible and critical concentration was found to vary between 6-100% and 2-97% respectively,” says the study.
“The lowest probability (6% and 2%) was observed on the day when there was a significant precipitation. During the weekend evening, the probability of exceeding the critical concentration was found to be 98% as compared to 10% during weekdays,” adds the study.
The study shows that pollution, even within cities, varies from one place to another. “There is a need to shift from city specific air quality management to location specific interventions,” says co-author of the study SM Shiva Nagendra. “This and earlier studies show there are many such hotspots in the city, where pollution levels are much higher than in other areas. This goes unnoticed. There is enough scientific evidence to show that sub-daily exposure to high PM levels can cause adverse health effects.”
Personal exposure
PhD Scholar Jyothi S Menon, another co-author, said personal exposure assessment is more important than ambient air. Jyothi said: “We do not know what kind of health hazards these concentrates would pose because there are no standards fixed. Ours is only a sample analysis and more research need to be conducted.”
The vehicular exhaust consists of particles of the smaller size range which can penetrate deep into the lungs. This is evident at IT corridor as the deposition at the pulmonary region was higher. While at beach promenade, the deposition at head region was higher which indicates the dominance of coarser particles.