Does new data suggest air pollution in Bengaluru is reducing? Nope, say experts

Data released by Union Environment Minister Prakash Javadekar showed a dip in PM10 levels in 14 cities including Benglauru, Delhi, and Vijayawada.
Does new data suggest air pollution in Bengaluru is reducing? Nope, say experts
Does new data suggest air pollution in Bengaluru is reducing? Nope, say experts
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On July 12, Environment Forest and Climate Change Minister Prakash Javadekar presented data related to air pollution for 2016, 2017 and 2018 in the Lok Sabha in response to a question on the rising pollution levels in the country. In the 50 cities surveyed, 14 cities, including Bengaluru, showed a trend of reducing PM10 particulate matter in the air in the given years.

The data had information about sulphur dioxide, nitrogen dioxide, PM2.5 and PM10 particulate matter in the air in cities in 19 Indian states. “With respect to PM10, 14 cities showed an increasing trend, 14 cities showed a decreasing concentration, 22 cities showed a fluctuating trend. With respect to PM2.5, trends are available for 17 cities and out of 17 cities, 8 cities showed an increasing trend, 04 cities showed a decreasing concentration, 5 cities showed a fluctuating trend,” it noted. Some of the cities where PM10 levels have gone down are Delhi, Varanasi, Ranchi, Raipur, Bengaluru, Vijayawada, Jameshedpur, and Malappuram, among others.

However, does reduction of particulate matter in the air mean that the air is getting cleaner? It’s not that simple, say experts.

PM10 and PM2.5 are respirable particles in the air. PM10 particles measure 10 micrometres or less in diameter; and PM2.5 particles have a diameter 2.5 micrometres or less.

Indian National Ambient Air Quality Standards (NAAQS) standards for concentration of PM2.5 are 40 µg/m3 (annual average) and 60 µg/m3 (24-hour average) in industrial, residential, rural or other areas. The limits for PM10 concentration are 60 µg/m3 (annual average) and 100 µg/m3 (24-hour average). The smaller particles are more dangerous because they tend to remain suspended in the air, not weighed down, and settle in the lungs and respiratory tract.

Data unreflective of reality

According to the National Air Quality Monitoring Program (NAMP) numbers provided, in Bengaluru, the annual average PM10 levels were at 103 µg/m3 in 2016. They dropped to 92 µg/m3 in 2017 and to 90 µg/m3 in 2018. Annual average PM 2.5 levels in the city were 51 µg/m3 in 2016, compared to 46 µg/m3 and 47 µg/m3 in 2017 and 2018 respectively.

For the many cities, including those surveyed in Kerala and Andhra Pradesh, there was no PM2.5 data available.

On face value, it may appear that a reduction in PM10 levels is a cause for cheer – it should mean that pollution levels are decreasing, right? This may not be the case, especially given that Environment Minister provided only the data from NAMP’s manual air quality monitoring stations.

Under NAMP, four key air pollutants - Sulphur dioxide, Nitrogen dioxide, PM10, and PM2.5 – are being monitored in 779 stations across 29 states and 6 Union Territories. These monitoring stations are of two kinds – continuous or real-time ones and manual ones. The problem with the data presented in the Lok Sabha is that it only takes into account the manual stations, say experts. Manual stations are required to record data for a minimum of only 104 days a year, typically two times a week for 24 hours: 4-hourly sampling for gaseous pollutants, and 8-hourly sampling for particulate matter.

Polash Mukerjee, the Lead for Air Quality at Natural Resources Defense Council, India, points out that the manual stations’ data is not as accurate as real-time ones. “It does not present an accurate picture especially when not backed up by data from the real-time stations,” he tells TNM.

Aishwarya Sudhir, Air Quality Program Lead, Health and Environment Alliance (HEAL), agrees. “Apart from the infrequency of data collection, in Bengaluru, many of the NAMP manual monitors are at places which have more greenery around. One needs to re-asses where the monitoring stations by the state are located,” she adds.

Further, Monitoring particulate matter in India: recent trends and future outlook, study published in September 2018, also points to an urban bias in the placements of the monitoring stations, with not many in rural areas. “This is relevant to note since residential combustion emissions, typically associated with solid fuel use, are a key source of air pollution across the country,” it says. The study also says that “outside of these 4-hour and 8-hour time periods, no data is collected at the manual stations based on publicly available information.”

Unfair to compare pollution in cities

In the aftermath of the data being released, there were reports on how the cities PM10 and PM2.5 levels compare to each other. However, this does not make sense, Aishwarya says.

She explains that each city has a peculiar pattern of pollution, which is affected by practices as well meteorological conditions. Unlike Delhi-NCR, Punjab, Haryana and other neighbouring states, where the pollution due to burning of crops for instance travels cross border, the sources of Bengaluru’s air pollution are within the city.

“Comparing cities when they have different kinds of pollutants and their factors is not sensible because their respective problems are very peculiar. One has to understand that the problem of poor air in Bengaluru is not similar to that of Delhi and the NCR states, the pollution levels in a city like ours are experienced at a much lower height owing to its sources - transport, waste burning, road as well as construction dust. The rampant dust being generated from Namma Metro expansion, rising bronchial and cardiac ailments in the city are certainly not indicative of the figures cited by the Hon'ble Minister,” Aishwarya argues.  

Further, Polash points out that the levels of PM10 dipping from 2016 to 2018 in cities including Bengaluru are hardly a cause for celebration. “They are still way above the NAAQS standards for ambient air quality,” he says, adding that it doesn’t make air pollution any less a cause for concern.

Need for multi-agency cooperation, transparency

Both Polash and Aishwarya stress on the need for cooperation between various government agencies to effectively tackle pollution.

“The data that was presented in the Parliament was given to the minister by the pollution control boards. This is not the first time that this has happened. However, we have noticed that the data provided by state pollution control boards is not entirely transparent – for instance, we have till date not been able to get the raw data for PM10 levels in the city. We don’t know when the data was collected, on what days, for what period of time,” Aishwarya says.

Further, given that air pollution has increasingly become a concern to ensure quality of life, there are tougher questions being asked to governments about what they are doing. Perhaps the reason why this arguably biased data was presented in the Parliament was because the Indian government too wants to be seen doing something about it, said an expert who did not wish to be named.

However, Polash says that air pollution is a complex problem which does not have overnight solutions. Aishwarya adds that even the state pollution control boards are overburdened, and have several limitations such as manpower. “They should not be left alone to deal with air pollution. Other government agencies should also support them,” she says.  

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