BANGALORE: Bus Day, the recently introduced initiative by the Bangalore Metropolitan Transport Corporation, appears to have had not many takers if one is to go by air pollution figures released by the Karnataka State Pollution Control Board.

The second edition of this initiative, which aims to motivate people to give up their vehicles and use public transport, took place on March 4, However, the pollution indicator figures indicate that compared to its previous edition (on February 4) the dip in pollution levels recorded at key traffic centres was not as substantial, KSPCB officials claim. While the RSPM (respiratory suspended particulate matter) levels — a critical indicator of air pollution levels — saw a decrease of 20.8 per cent on February 4, the Bus Day held last week on the Bannerghatta Road route recorded a decrease of 13 per cent in RSPM.

Cleaner air

KSPCB officials, who recorded pollution levels at different points using their mobile vans, found that there was indeed a change in general air quality on both occasions. In all these locations, a recce on days prior to Bus Day recorded values of RSPM and nitrous oxides exceeded national ambient air quality standards. Other parameters — sulphur dioxide, carbon monoxide and ozone — did not exceed ambient air quality standards.

This Bus Day, pollution levels recorded on the Marathahalli bus rote recorded a decrease in RSPM (13.5 per cent), sulphur dioxide (14.7 per cent), nitrous oxide (13.59 per cent), carbon monoxide (12.73 per cent) and ozone (7.2 per cent). On subsequent days, the pollution levels also bounced back to old levels.

Anomaly

Curiously, while the dip in nitrous oxides, sulphur dioxide and RSPM decreased (when the two Bus Days are compared), that of carbon monoxide bucked the trend. However, KSPCB officials said this could be due to a variety of reasons. Though both Bannerghatta Road and Marathahalli routes lie on traffic-intensive roads, the composition of air in both regions may be different, the official said. “RSPM levels are the best and clearest indicators of pollution, going by which there is a dip in the effect the initiative has had on the ambient air quality,” the official explained.

The official, however, pointed out that they found that by evening, when traffic was at its peak, the frequency of the buses reduced, countering the good effects of the morning. This means that those who took a bus to work in the morning could well have taken less eco-friendly means back home.