Winter air dangerously toxic in Mumbai

  • Badri Chatterjee, Hindustan Times, Mumbai
  • Updated: Dec 29, 2015 00:38 IST

This year, the winter chill has also brought with it poor air quality. A recent study revealed the concentration of particulate matter 1 (PM1) – pollutant particles less than one microns that can get lodged in the lungs and bloodstream –seems to have risen between October and December.

A first-of-its-kind study for the city by System of Air Quality and Weather Forecasting and Research (SAFAR), found that PM1, which is largely released from vehicular exhaust – rose from 33 microgrammes (µg) per cubic metre (µg/m3) for October to 37 µg/m3 in November and 45 µg/m3 in December.

The concentration of PM1 was less in the months of August and September – 13 µg/m3 and 19 µg/m3 respectively – when rain washed the pollutants away.

“Unfortunately, India does not have any defined standard for PM1 particles,” said Gufran Beig, scientist at Indian Institute of Tropical Meteorology (IITM), Pune and project director, SAFAR.

“That’s because very few studies have been carried out globally to test this pollutant. The standard for slightly larger particles called PM 2.5 (particles less than 2.5 microns) is 60µg/m3. It is found that PM1 constitutes 30-40% of PM 2.5. The current levels of the pollutant in Mumbai are quite high and extremely dangerous for people sensitive to air pollution,” said Beig said.

SAFAR carried out separate studies at their nine monitoring sites in the city and found PM1 levels to be high at all the sites. The highest levels of PM1 were observed at Bhandup, which recorded 67µg/m3 in October, followed by Navi Mumbai at 50 µg/m3. In December, however, Chembur, Mazgaon and Navi Mumbai recorded the highest PM1 levels at 59 µg/m3, 53 µg/m3 and 55 µg/m3 respectively.

Beig said PM 2.5 particles, which are considered lethal to the cardiovascular system, had raised an alert in many nations. “Ultrafine PM1 particles were recorded to be way higher than national air quality standards. These particles penetrate tissues in the cardiovascular system leading to related diseases,” he said.

The levels of other pollutants that are taken into account while measuring the air quality index (AQI) — a pollution-measuring indicator – have been within safe limits for the period. Apart from particulate matter (PM1, PM2.5 and PM10), SAFAR also looks at the concentration of sulphur dioxide (SO2) — produced from the burning of fossil fuels (coal and oil) and nitrogen dioxide (NO2) — largely released by vehicles and fuel combustion. While SO2 levels were within safe limits for December, NO2 levels for Mumbai were calculated at 41.50 parts per billion (ppb) as against a safety limit of 42 ppb during December.

Scientists said there are serious health implications from the high levels of PM1 particles in the air.

“The proportion of PM1 is about 35% of the PM2.5 emissions in Mumbai, which is quite high. PM1 is found to be higher in locations close to slum areas, which indicates that bio-fuel emissions are contributing more to this pollutant, which are most likely to be black carbon from domestic cooking,” said Vivek Chattopadhyay, clean air programme manager, Centre for Science and Environment, Delhi.

Doctors said initially it was thought these particles were so small they would leave the body without any damage, but subsequent studies have found these can lead to serious health problems.

“Asthma, bronchitis, hypersensitivity pneumonitis [inflammation of lung tissue], chronic obstructive pulmonary disease (COPD) and bronchitis can all be triggered from such fine pollutant particles like PM1,” said Dr Sanjeev Mehta, pulmonologist (lung specialist), Lilavati Hospital in Bandra.

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