Wednesday, September 23, 2009

Frequently Asked Questions: (5) Is Transport the Main Culprit of Air Pollution?

A common question with a difficult answer of “it depends”. Yes, the transport is growing rapidly in most of the developing country cities and the quotient its contribution to local and global air pollution problems is also increasing significantly. Yet, the answer lies in the mathematics of the points raised in the earlier questions.

On one side, the visibility of the growing sector creates an atmospheric cloud that multiples its contribution. Since the people are spending more time on the roads, because of traveling or due to sitting in a congestion zone, tend to experience the most and in such situations, the contribution of transport seem like the main culprit.

Yes, along the main corridors of the major cities, the contribution of the transport sector is the main culprit. However, city as a whole, it is important that a holistic picture and understanding of the sources (including the domestic and industrial) is established before a decision is made on the contribution (source apportionment).

For example, during the Olympics, the city of Beijing, did not achieve the reductions in the air pollution levels by cutting the vehicular fleet by half for the games period. They were able to achieve this reduction in conjunction with closing down a number of small and large industrial sites in the city.

Now, the long range transport plays a critical role. The transport emissions are ground based and tend to increase the local concentrations significantly. However, the industrial sector contributes farther distances. And for pollutants like sulfur dioxide, the transport quotient is even higher and this was also evident in Beijing during the games. A series of measures, based on the modeling studies, resulted in closing down of industries in the neighboring cities, to achieve the necessary air pollution reductions during the Olympic Games.

So, transport is an important culprit, but not necessarily the main culprit at all times.

Another example is Delhi. In 2001-02, while the bus fleet was being converted from diesel to CNG, a major intervention in the industrial sector was to relocate a significant number of smelters out of the city limits, which resulted in significant reductions. However, all the reduction are wiped out due to large increase in the car population; different story !!

See AQM in Delhi - Then, Now, and Next.
See Beijing to Delhi - Traffic problems highlighted
See Nano-carnomics in Urban India

See other FAQ's.

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