Gaps in estimating Bengaluru's air pollution

Bengaluru isn't near the Delhi level yet when it comes to air pollution, but that doesn't mean all is well

Winter mornings are dusty and smoggy in most areas of Bengaluru, with polluted air. Meanwhile, Karnataka State Pollution Control Board’s (KSPCB) live air pollution monitoring system shows all parameters in green in most areas, which gives a feeling of everything being allright.

“I was behind BBMP asking for sweeping machines in our area to remove dust from roads. Along with vehicular pollution, dust on the road is too high and winter is adding to our woes. The KCDC composting plant nearby emits a foul smell.. it is a major health hazard,” says Lalithamba B V, a resident of HSR Layout. Areas where constructions are going on are the worst hit.

KSPCB’s monitoring network does not cover HSR Layout. The nearest high-precision air pollution monitoring system, called Continuous Ambient Air Quality Monitoring Station (CAAQMS) is near Silk Board, which on most days shows “moderate” level of air pollution.

Bengaluru has seven CAAQMSs by KSPCB and three by Central Pollution Control Board (CPCB), which are high-precision instruments that generate data on particulate matter, sulphur, nitrogen and carbon-based gases. The data from these is used to come up with policies that guide air pollution mitigation. The city has 13 more manual monitoring systems, which do not provide live data.

Bengaluru’s population was 84,43,675 according to the 2011 census. Indian Standard (Part 14) (Methods for Measurement of Air Pollution), released by the Bureau of Indian Standards (BIS) specifies the criteria for installing monitoring stations. According to this, if we go purely by population, a minimum of 17 ambient air quality monitoring equipment are required to measure air pollution, including suspended particulate matter (SPM) and sulphur dioxide (SO2).

However, the same document also says that to analyse air quality trends, “A city with a population of 5 to 10 lakh should have 5 to 10 monitoring stations distributed so that one station represents 10 to 20 km2.” This means that for 700 sqkm of area, Bengaluru needs a minimum of 35 stations. Again, it’s ambiguous.

The number also depends on the population density but there is no clear definition or guideline. The standards suggest one station per 5 to 10 km2 in cities with a large population with complex topography or with an unusually large number of pollution sources.

An under-monitored city?

“The estimated requirement for air quality monitors in Bengaluru was 41, but since 2018, the number of real-time monitoring stations has remained the same,” says Aishwarya Sudhir, who was Air Quality programme lead, Health and Environment Alliance (HEAL).

“There is a visible problem of road dust across the city. Several stretches where the roadworks and metro expansion is underway are particularly bad. Monitoring has to be mandatory across some of these corridors; regular and localised mitigation measures have to be adopted immediately to safeguard public health,” she adds.

So, does the city have enough monitors?

“If we combine sensors and reference monitors, then the answer is a yes. The sensor data typically needs some correction against the reference stations data for calibration and then can be used for policy discussions,” says Sarath Guttikunda, Founder of Urban Emissions.

“No, they are not enough, but under the NCAP programme, they are introducing four more monitoring instruments. These equipment are costly, including maintenance. There is a recent notice that says the money that comes to cities under NCAP should not be used for buying these instruments, so the funding of new monitoring stations is a challenge,” says Pratima Singh, a senior air pollution research scientist at CSTEP who is a part of a team that worked with the KSPCB on air pollution studies and policies.

The CPCB notification issued in November 2022 bans municipalities and state pollution boards from buying new monitors using the 15th finance commission grants earmarked for the national clean air programme (NCAP).

This is because, “A few cities are putting all the money into buying and installing monitoring stations, just to show the spend. It’s huge money with each instrument costing more than Rs 1 crore. It’s a waste of money, it defeats the purpose, we need to implement strategies, instead of just using the money to implement the monitoring network,” she opines.

“City government can tap into resources from environment department or state pollution control board to set up a monitoring network,” she says. However, “lack of sufficient monitors in a city should not be a reason to not implement solutions,” she adds.

She says that according to CPCB guidelines monitoring systems need to be put in all representative areas of a city: Industrial areas, traffic junctions, domestic areas and on kerbside, which provide enough data to help formulate policies.

Low-cost sensors not recommended

In a city like Bengaluru measuring more than 700 sqkm, to know what’s happening on the air pollution front at a ward level or to go hyperlocal, the city needs more devices. For example, to prioritise which area to introduce the sweeping machine to, the BBMP technically needs to compare local data of PM10 and PM2.5 (particles under 10 and 2.5 micrograms respectively) and see where there is more dust which can be cleaned by the sweeping machine, say experts.

Low-cost air pollution sensors are used in such situations, in order to get a sense of pollution in an area, by various organisations. However, in a notification issued in March, CPCB banned the usage of data from low-cost sensors for public information and air quality index generation.

The reason is related to technicalities. “These are not of reference grade. You can get a device ranging from Rs 5000 to Rs 2-3 lakh. These instruments need to be calibrated before usage, and then only collect the data. But lack of technical understanding on using these instruments has lead to misleading numbers,” says Pratima.

The second reason, she says, is that the data obtained from these instruments is not appropriate to develop an air quality index. While CPCB notice doesn’t ban the usage of low-cost sensors for monitoring and research purposes, developing policies from such data is not recommended. Non-calibrated data or generalising the near source data will be a wrong representation leading to panic situations among citizens.

Lack of local information

However, not having hyperlocal pollution information makes many polluted areas to remain unmonitored with no interventions to fix the issues, while the residents are left to bear the cost of it.

For example, the KSPCB has its CAAQMS in two places, ie on Bapuji Nagar in Mysore Road and in Silk Board junction. On November 28, the air quality at Bapuji Nagar on Mysore Road dipped to ‘very poor’ level with an Air Quality Index of 301, PM2.5 and PM10 being the primary pollutants. The monitoring station at Silk Board also continuously records moderate or poor air quality.

While these are the only two major traffic junctions that are monitored, many other trafficked junctions go unnoticed and may escape policy interventions, says an expert.

With moderate pollution, people with respiratory allergies are likely to be affected. A major pollutant in Bengaluru’s air is carbon monoxide, which can act as a slow poison for overall health, specifically the brain. Bengaluru’s air is full of these three pollutants and the long-term health effect is not difficult to foresee.

“Four years ago we conducted a study on traffic police, bus drivers and conductors on the effects of air pollution. We found airway obstructions among those who looked normal. We wanted to extend the studies,” says Dr Nagaraj, director of Rajiv Gandhi Institute of Chest Diseases. He says the state government has asked the Institute to conduct studies on chronic lung diseases, and they will start the studies after the existing vacancies are filled up.