Last two winters, the political atmosphere in Delhi has been the focus of the country. This winter, for every right reason, the pollution in atmosphere (NOT metaphoric pollution, thankfully) has been the focus of attention. Delhi saw fifteen days of odd-even rule and it is time we should honestly assess its impact during this period. As mentioned in my previous blog-post, I had been tracking the air pollution levels using open data available at various monitoring stations in Delhi for more than a month. The objective was to understand how much reduction in Particulate Matter (PM) pollution would we see if almost half of Delhi's private-owned-four-wheel-vehicles are removed from the road.
I appreciate the maturity and civic sense by which most of Delhi accepted this personal inconvenience, which had most definitely reduced traffic on road, resulting in substantial reduction of commuting time and improving response time of ambulances throughout the city. Beyond this, it is very unfortunate that I find no conclusive evidence that removing half of private-owned-four-wheel-vehicles will help control air pollution in this city at all. I had mentioned earlier that PM pollution rose during the first three days against all anticipation, but within few days there was a decrease and today PM2.5 levels are 19% lower than what it was on 3rd January while the PM10 levels have reduced by 40%. This can be seen from graphs of PM2.5 and PM10 levels plotted below.
Fig. 1: Comparison of PM2.5 AQI measured at various monitoring stations in Delhi with Wind Velocities and Relative Humidity
Fig. 2: Comparison of PM10 AQI measured at various monitoring stations in Delhi with Wind Velocities and Relative Humidity
Obviously, today air pollution is better than 3rd January, but the reason of my disappointment can be articulated by following two observations:
- PM levels are still more than acceptable levels, keeping Delhi in the category of one of the worst polluted cities, if not worst. This means, the air in Delhi is still "hazardous" for anyone living in this city.
- Overall reduction in air pollution seem to be due to weather and have no impact of reducing private-owned-four-wheel-vehicles.
I make the above conclusion based on observed AQI levels in Delhi. A definite trend is observed between PM concentration and wind velocities in the city. PM10 concentration across the city reduces by 60%-70% on days when wind velocities reach 8 Km/h to 11 Km/h. The effect of wind velocities on PM2.5 is not exactly same as the rate of reduction in PM2.5 concentration is less than half when compared with PM10, however I can conclude that a trend is also observed here. A careful analysis of relative humidity on non-windy days in Delhi presents a positive correlation of PM pollution in air with humidity in air. On days with high relative humidity, the air pollution observed is higher and vice versa.
With this in mind, when you look at the AQI levels during the first week of odd-even rule, a definite increase in air pollution is observed. On 8th January, the PM2.5 levels are second worst since 23rd December 2015 while PM10 levels reached its worst levels during the same period. These observations does not present any correlation with reduction in private-owned-four-wheel-vehicles with air pollution of PM. As mentioned before, I do acknowledge the achievement of odd-even rule in reducing traffic congestion but it will be wrong & ignorant to attribute the reduction in pollution that we observe on 15th-16th January to the odd-even rule.
Today we are at the same place where we were a month ago regarding the air pollution in Delhi. Apart from Odd-Even rule, I have not seen any initiative by state or central government to reduce the emission of PM in atmosphere that is still not on paper. It will not be wrong to say that odd-even rule has failed to serve its purpose but we do not have time to eulogize this failure. We must be proactive in finding solutions and the first thing we must honestly do is to acknowledge that this is not a easy problem to solve. Most countries are facing the threats of rising pollution. Cities in developed countries like London & Milan are facing similar concerns of rising pollution with more or less similar failures to control it.
Delhi and Beijing are world's most polluted mega cities and this is why we assume this to be a developing world problem but the scale of impact is global. It is therefore important for us to characterize and understand the cause of PM pollution to much greater detail. A lot of scientific studies are already available, including those in India, specifically addressing the air pollution in Indian metros. We must use these findings as guidelines to build comprehensive framework for hydrocarbon based fuel burning to address this issue of air pollution.
Most of these studies indicate that implementation of any one strategy like odd-even rule will not be able to achieve significant reduction. With regards to pollution in Delhi, the data indicate that we have already implemented measures like introduction of higher emission standards of almost all vehicles including 2 wheelers and 3 wheelers, introduction of CNG for 3 Wheelers, taxis and buses, regulating sulfur content in diesel, ban on more than 8 years old buses, etc. in Delhi during last 15 years. With more than 200 Kms long metro rail service, Delhi is also placed as a city with one of the most viable public transport in the country. So, it will not be honest to blame past Governments for today's situation.
With all this in mind, to get further incremental reductions, the efforts required
would be much more than banning half of privately owned vehicles for a fortnight.
Some old studies point that transportation is responsible for 26% PM2.5 emission in the city. Of all the transport on road, share of four wheelers is 10% and reducing half of these vehicles will only present reduction of 1.3% of total emission in Delhi, if I dare to apply linear extrapolation. This definitely is not adequate response for the kind of crisis this city is facing today!
Thanks to wind, today the pollution in Delhi is even lower than what it was on 15th January. I will be discussing further on my findings about control options and studies done on Particulate Pollution in India soon. Till then, breathe easy Delhi.
With this in mind, when you look at the AQI levels during the first week of odd-even rule, a definite increase in air pollution is observed. On 8th January, the PM2.5 levels are second worst since 23rd December 2015 while PM10 levels reached its worst levels during the same period. These observations does not present any correlation with reduction in private-owned-four-wheel-vehicles with air pollution of PM. As mentioned before, I do acknowledge the achievement of odd-even rule in reducing traffic congestion but it will be wrong & ignorant to attribute the reduction in pollution that we observe on 15th-16th January to the odd-even rule.
Today we are at the same place where we were a month ago regarding the air pollution in Delhi. Apart from Odd-Even rule, I have not seen any initiative by state or central government to reduce the emission of PM in atmosphere that is still not on paper. It will not be wrong to say that odd-even rule has failed to serve its purpose but we do not have time to eulogize this failure. We must be proactive in finding solutions and the first thing we must honestly do is to acknowledge that this is not a easy problem to solve. Most countries are facing the threats of rising pollution. Cities in developed countries like London & Milan are facing similar concerns of rising pollution with more or less similar failures to control it.
Delhi and Beijing are world's most polluted mega cities and this is why we assume this to be a developing world problem but the scale of impact is global. It is therefore important for us to characterize and understand the cause of PM pollution to much greater detail. A lot of scientific studies are already available, including those in India, specifically addressing the air pollution in Indian metros. We must use these findings as guidelines to build comprehensive framework for hydrocarbon based fuel burning to address this issue of air pollution.
Most of these studies indicate that implementation of any one strategy like odd-even rule will not be able to achieve significant reduction. With regards to pollution in Delhi, the data indicate that we have already implemented measures like introduction of higher emission standards of almost all vehicles including 2 wheelers and 3 wheelers, introduction of CNG for 3 Wheelers, taxis and buses, regulating sulfur content in diesel, ban on more than 8 years old buses, etc. in Delhi during last 15 years. With more than 200 Kms long metro rail service, Delhi is also placed as a city with one of the most viable public transport in the country. So, it will not be honest to blame past Governments for today's situation.
With all this in mind, to get further incremental reductions, the efforts required
would be much more than banning half of privately owned vehicles for a fortnight.
Some old studies point that transportation is responsible for 26% PM2.5 emission in the city. Of all the transport on road, share of four wheelers is 10% and reducing half of these vehicles will only present reduction of 1.3% of total emission in Delhi, if I dare to apply linear extrapolation. This definitely is not adequate response for the kind of crisis this city is facing today!
Thanks to wind, today the pollution in Delhi is even lower than what it was on 15th January. I will be discussing further on my findings about control options and studies done on Particulate Pollution in India soon. Till then, breathe easy Delhi.
No comments:
Post a Comment