Drive in Bangalore to choke on poisonous air

If you travel on Sarjapura Road regularly, please block your nose the next time you do so. Do the same if you are passing through Magadi Road, Jeevan Bhima Nagar, Hennur Ring Road, Banashankari Ring Road and Lalbagh Road, for the suspended particulate matter (SPM) and sulphur dioxide levels in the air, a measure of the extent of pollution, on these six roads are way beyond the prescribed safety limits. This was revealed by a recent survey conducted by a team of college students and environmentalists.

These roads and four others — NGEF Road, Mekhri Circle, Bannerghattta Road and Race Course Road —  were taken up for the study, titled “Impact of street tree canopies on pollution and micro climate in Bangalore”, which was conducted by Mount Carmel and St Joseph’s colleges under the guidance of Dr Harini Nagendra, DST Ramanujan Fellow and Urban Ecology coordinator at Ashoka Trust for Research in Ecology.

“A 200-metre stretch on each of these 10 roads was surveyed during the monsoon in July-August 2009. It was found that there was a 10 degree Celsius difference in the temperatures at places with and without tree cover. A similar study will be conducted this  summer and the results, we are sure, will be even more shocking as many trees have been felled in this interregnum,” Dr Harini said.

On a tree-shorn stretch of Sarjapura Road, the SPM level was found to be about 717 micrograms per metre cube (MPMC) as against the National Ambient Air Quality standard of 180 MPMC. This was treble that of the SPM level on a green stretch here.
As against the desired sulphur dioxide levels of between zero and 60 MPMC, Lalbagh Road showed 53 MPMC.

K Sankara Rao from the Centre for Ecological Sciences in Indian Institute of Science, said that increasing pollution levels would result in health problems, including respiratory complications.
While the city, especially major roads, have been stripped of tall old tree cover, the pollution levels are higher on roads that lost tree cover to road widening and infrastructural works.

Dr Harini observed that over the years, a number of major trees had been lost. But there was neither any databank on the exact number of trees nor a policy in place to control the unbridled felling, she said.

Dr Harini, who has visited several nations, said, though the tree-diversity in Bangalore was better than that in Beijing, Mexico, the US and north Europe, the tree density was much lower.
She said that the Bruhat Bangalore Mahanagara Palike (BBMP) had also planted exotic tree species in place of felled trees, instead of planting native species like tamarind, mango, ficus, rain trees and copper pod.

BBMP forest cell deputy conservator of forests, SA Hubert, told DNA that big leafy trees could not be planted on major city roads as after 10 years they would have to be felled. He said experts were being consulted to identify the right tree species that could be planted on major roads and residential roads.