Road dust accounts for up to 50% of Bengaluru pollution: Study

Even if the transportation sector’s contribution to air pollution (20%-40%) is brought down to zero, the broken roads of Bengaluru will continue to pump dust into the lungs of its residents. According to a study by the Centre for Study of Science, Technology and Policy (CSTEP), soil and road dust accounts for 25% to 50% of harmful particulate matters in the city.

Researchers from CSTEP looked into the sources of pollution in Bengaluru, one of the 122 cities identified as violating the national ambient air quality standards by the National Clean Air Programme.

The study, which began in 2019, is based on data from extensive surveys conducted in 32 locations across the city.

Besides identifying the sources, the study estimated that in 2019, around 24,600 tonnes of PM10 and 14,700 tonnes of PM2.5 were emitted from the BBMP area. The last time the city’s pollution was quantified was in 2010, when The Energy Resources Institute measured its PM10 load at 19,856 tonnes.

While national models have already estimated the levels of PM2.5 — flagged as harmful due to their ability to penetrate bloodstream and raise the risk of lung and heart diseases, stroke and cancer — CSTEP’s findings come as a stark warning for the city.

The study also identified the sources of polluting particles, with transportation recognised as the main contributor (39.9%) of PM2.5, followed by dust (25.3%) and secondary sulphate (13.2%) from coal, wood burning and industrial emissions.

When it comes to the bigger particles (PM10), soil and road dust led the chart by accounting for 51.1% of pollution followed by transportation (18.6%).

The study suggested ways to control dust re-suspension, from vacuum sweeping to end-to-end pavements with green cover and others. It also stressed the need to check construction dust.

Responding to a question, Pratima Singh, Research Scientist at CSTEP and one of the authors of the study, said that policy push for electric vehicles (EV) was in the right direction. “The importance of good roads seems to have been recognised considering the importance being given to new road infrastructure like white-topping. It may take time. However, in a growing city like Bengaluru, dust will continue to play a problem,” she said.

Asked about the role of poor roads in tail-pipe emission, she said a transport-specific model that considers emissions from different vehicles on different conditions of roads has to be developed. “There is an increased interest of authorities like the BBMP to take the lessons from this study to line departments to come up with a sound implementation strategy. We hope to see good results,” she said.