Planting Trees Will Provide Clean Air To Pune?

Pune has several hills scattered throughout its extents. About 1600 odd hectares of them going by the various sources. Some of the hill land is owned by government and is managed by the forest department, some is government owned and is covered by slums and some is under private ownership.

There is a grand plan to convert all or most of this 1600 odd hectares into bio-diversity parks. While the idea of setting aside large swaths of hills as open spaces is creditable, reporting by the media on the supposed benefits of these parks verges on the side of being silly.

Here are a couple of examples I see again and again in media reports on this issue, most recently in yesterday's Times of India (Nov 12 2010, Pune edition):

Air pollution in Pune is a threat to health and well being. The United Nations recommends at least 12 sq m of green area per person for adequate environment for physical and mental health.

An average family of five will require 60 sq m of green area to survive and breathe. Once it comes up, the BDP's will provide clean air for approximately 35 lakh people.

BDP's are the bio-diversity parks and 35 lakhs equals 3.5 million.

Reading this strange environmental calculus makes me wonder how people in Tokyo, Hong Kong, Dubai and Las Vegas, cities with either hyper dense populations or ones bereft of any greenery manage to live healthy lives.

Going by the U.N criteria as presented in the Times of India (TOI) all the people in these cities should be diseased wrecks by now.

The fact is that the greening of the hills will not make a dent in either offsetting carbon dioxide emissions or preventing other types of air pollutants. Pune by a rough estimation of the number of vehicles (approaching 2 million) likely emits more than a million tons of carbon dioxide a year from vehicles alone (here is another estimate). There are other sources that add to this.

1600 hectares of the Utopian forest that may or may not come up on these hills will sequester at most a few thousand tons of carbon dioxide per year. That is the best case scenario. Most likely the number will be disappointingly smaller. Currently the forest on these hills sequester a few tens of tons per year according to this study on carbon sequestration in Pune.

Besides trees don't suck in particulate matter and sulfur and nitrous compounds which have ill effects on health. More than CO2, these pollutants pose an immediate threat to our health. These continue to be emitted in large quantities mostly as vehicular emissions and tree plantations won't reduce their presence in the air above Pune.

I would like to see at least parts of these hills being left as open spaces..there are clear benefits in terms of providing cool recreational spaces for citizens and as a refuge for the urban bird and animal populations. But whether those hills are left barren or are built upon or are completely covered by trees won't make a difference in terms of providing clean air to the city.

That will happen only through cleaner and more efficient use of energy sources particularly a move towards cleaner vehicular fuels.