People living in Mumbai and Navi Mumbai have been breathing polluted air, which falls under the “poor to severe” category for a considerable number of observations throughout 2013-14, found a report on the air quality status of Maharashtra, published by the Maharashtra Pollution Control Board (MPCB). The report was prepared by The Energy and Resources Institute (TERI) based on air quality data monitored by MPCB.

Ambient air quality monitoring stations (AAQMS) at Sion and Bandra recorded ‘moderate’ and ‘poor’ air quality for 70 to 80 per cent of the recorded observations, while ‘poor’ or ‘moderate’ air quality was recorded for more than 35 and 60 per cent of the observations respectively at Navi Mumbai and Panvel. Data for air quality is regularly recorded by the AAQMS of MPCB, which monitor three parameters, namely respirable suspended particulate matter (RSPM), oxides of nitrogen and sulphur dioxide.

Of the 72 active AAQMS in the state, two are located in Mumbai at Sion and Bandra and seven in Navi Mumbai.

In the state, RSPM was found to exceed annual standard at almost all (70 out of total 72) monitoring stations, while annual oxides of nitrogen concentrations exceeded the standard at one-third of the stations monitored.

The ambient air pollution is assessed by calculating the air quality index – while AQI range of 0-80 microgrammes per cubic metre for sulphur dioxide and oxides of nitrogen and 0-100 microgrammes per cubic metre for RSPM indicated ‘good’, an AQI of more than 150 microgrammes per cubic metre for RSPM and more than 368 microgrammes per cubic metre and 181 microgrammes per cubic metre for sulphur dioxide and oxides of nitrogen indicates ‘poor’.

Of the three pollutants, the report found RSPM to be the major cause of pollution in Navi Mumbai, and in Mumbai, it found RSPM and oxides of nitrogen to be the major cause.

In 2013-14, Sion recorded the highest annual concentrations of nitrogen oxide of about 106 microgrammes per cubic metre, more than 2.5 times the standards. In Navi Mumbai, areas like Panvel, Taloja and Mahape were among the top five AAQMS that recorded highest RSPM concentrations in 2013-14. The various quarry sites in the vicinity could be attributed to high RSPM concentrations in this region, the report added.

Although RSPM pollution is on a decline in Mumbai region, the annual concentrations across the decade has been almost two to three times the annual standard, the report found. Thane and Raigad regions have, in the past three years, recorded an inclining trend for annual RSPM concentrations, the report said.

As per Indian Petroleum and Natural Gas statistics for 2012-13, Maharashtra has the highest number of registered vehicles and consumes the maximum amount of fossil fuels in the country.

“Sulphur dioxide and oxides of nitrogen are irritants to the airway, depending on the size of RSPM and where they deposit themselves in the lung, they can cause inflammation and definitely decrease the lung capacity, which is what makes people breathless,” said Dr Amita Athavale, head of environmental pollution research centre at KEM Hospital.