The concentration of suspended pollutants, which can be inhaled in to the body, was nearly eight times the permissible limits during the mornings last week in residential areas close to the Deonar dumping ground.
Hourly data from the Chembur air monitoring station set up by the System of Air Quality Weather Forecasting and Research (SAFAR) revealed that of levels of PM10 — air-borne particulate matter measuring less than 10 microns — were as high as 788ug/m3 as against a safety limit of 100ug/m3 between 8am and 9am; and 718 ug/m3 between 7am and 8am on January 29, two days after thick smog was released from the fire at the dumping ground.
Similarly, PM2.5 — pollutants measuring 2.5 microns or less — between 8am and 9am were 583ug/m3 as against permissible standards of 60ug/m3; and 538ug/m3 between 7am and 8am on January 29.
PM, which consists of soot, organic matter and chemicals, can stick to the sides of the windpipe or travel deeper into the lungs.
Researchers from SAFAR, however, said no health warnings can be provided for hourly data as the air quality monitoring and forecasting agency of the government only analyses a daily average based on readings every 24 hours.
In case of PM1 — pollutant particles less than one micron — the levels were as high as 311ug/ m3 between 7am and 8am; and 330ug/m3 between 8am and 9am on January 29. However, no safety standards have been set for these pollutants as they are so small that they can enter the blood stream.
“Hourly data just indicates the accumulation of pollutants over a specific time frame, which allows us to calculate the average air quality during the day. It cannot indicate a health hazard as it is too small a time frame as compared to 24 hours to summarise the air quality at a particular location,” said Gufran Beig, project director, SAFAR, adding that overnight pollution levels were higher than those recorded during the day. This has been the trend since the additional source of pollution – biomass burning at Deonar dumping ground – began last Wednesday.
“Due to a fall in temperatures during the night, pollutants emanated during the early hours of the day get suspended faster around the eastern suburbs. But, later in the day, pollution decreases marginally owing to increase in temperatures and other meteorological factors,” he said.
The air quality index (AQI) – a composite pollution measuring indicator that takes into account PM levels, apart from concentration of five gaseous pollutants — on January 29 was at 325, which falls in the ‘very poor’ category in the morning, and further shot up to 341 by the evening, which was the highest since June last year when air quality monitoring and forecasting began in Mumbai.
The health advisory issued by SAFAR on the basis of the 24-hour average AQI on January 29 said, “The current AQI levels trigger a health alert for everyone. People sensitive to air pollution are advised to remain indoors and everyone is advised to use pollution masks.”
Doctors pointed out that the maximum number of heart and lung related cases were seen on January 29. “Although high hourly pollutant readings may not have a collective impact throughout the day, it is indicative of the quantum of pollutants inhaled by residents of Shivaji Nagar, Govandi and parts of Chembur close to the dumping ground and are unaware about it,” said Dr Sandeep Rane, cardiologist, Rane Hospital in Chembur.