The odd and even scheme has helped to arrest the peaking of pollution in Delhi when hostile weather—no-wind condition, dipping of temperature and western disturbance—trapped toxic pollution
Credit: Flickr The Delhi High Court on Monday ruled that Delhi government’s odd-even scheme would continue till January 15 as planned.
The court said it would "not interfere with the notification". However, the judges added, the government, must consider some of the issues raised by petitioners on odd-even if it implements such a scheme again.
The court’s decision follows the claims of a group of lawyers that the week-long implementation of the scheme had not made any difference to Delhi’s air quality but had caused personal inconvenience to car users. Therefore, it had to be discontinued.
Late last week, senior counsel Harish Salve, appearing for the Delhi government, submitted before a Bench of Chief Justice G Rohini and Justice Jayant Nath, a status report on air pollution and the impact of the odd-even scheme from the Environment Pollution (Prevention and Control) Authority or EPCA. Salve argued that the scheme was an emergency response to the “emergency” situation that had arisen because of the high air pollution level in Delhi. The scheme had made a “definite positive” effect and had arrested the peaking of the air pollution level. It, therefore, had to be continued.
Evidence of change
The status report submitted to the Chief Justice Bench has highlighted the air pollution trends this winter has shown. Cold temperature, lower mixing height of air, calm and no-wind conditions trapped air and pollution. This has necessitated tougher emergency action to reduce pollution.
The winter months of November and December 2015 show a higher number of days in the “severe” category—four times the safe standard—which is the worst category according to the National Air Quality Index. November 2015 had 73 per cent of days in the severe category against 53 per cent in November, 2014. December 2015 has 67 per cent of days in the severe category as against 65 per cent in December 2014. December 2014 at least had 3 per cent of days in the “good and satisfactory” category but December 2015 has none. There has not been a single good air quality day this winter. On several consecutive days, the PM2.5 levels have remained in the worst category according to the National Air Quality Index.
The odd and even programme has been implemented as an emergency action to arrest the high emergency peak when the overall pollution levels have gone 5 to 6 times higher than the standards. This is needed to protect public health in a city where every third child has impaired lungs.
The EPCA note has pointed out that this is also not the only action that is being taken in the city to arrest runaway air pollution. The Supreme Court has taken firm steps to check heavy commercial vehicles from entering Delhi; it has issued directions on enforcement of construction and road dust as well as garbage burning. The Delhi government is also bringing action against the Badarpur Thermal Power Plant. The odd-even scheme is designed for immediate refief as it takes off the roads almost half the private cars, which contribute to pollution from their tailpipe and pollution because of congestion.
The odd-even scheme has resulted in the lowest pollution peak compared to the previous high smog episodes this winter: An analysis carried out by the Centre for Science and Environment (CSE) has shown that this winter, out of all the severe smog episodes so far (with several consecutive days in severe category) the peak pollution during the odd and even programme has been the lowest. This shows that despite the hostile weather conditions—no wind, temperature dip and western disturbance, the peak pollution during the odd and even scheme has been much lower. The earlier smog episodes have seen much higher peaks and much more rapid build-up compared to the rise that happened during the first week of the odd and even programme. This proves reduced traffic volume has arrested the peaking of pollution. The first week of winter has witnessed worse weather conditions and yet the peaking of pollution has been lower.
This validates the importance of emergency action. Because of the odd-even scheme in operation, the pollution peak is less and so, air is less hazardous (or not as hazardous as it could have been in these conditions). This is why governments take emergency action. This is why odd-even scheme is so necessary in winter months, when pollution peaks.
Graph 1: Drop in the intensity of smog episodes due to odd and even programme in week 1
During the odd-even programme, day time, even with lower wind speed has shown faster drop in pollution: It is also clearly evident from the air pollution data that despite the lower wind speed on some days during the odd and even scheme, pollution has fallen during those hours. The CSE analysis has further shown that it is notable that during days before the programme was started, pollution levels had increased when wind speed was low. This brings out the clear impact of the odd and even scheme on the pollution levels. Even when wind was not there to blow it away, the scheme succeeded in arresting the upward trend. Both, the real time pollution and wind data are from the Delhi Pollution Control monitoring stations.
Graph 2: Odd and even days in Delhi show that even on days without wind pollution levels declined as opposed to pre-scheme days
Pollution load from cars are lower; per capita emissions of car users is also down during the odd and even programme: The EPCA status report has also cited findings that show that both, particulate and nitrogen oxide load from the cars have reduced substantially during the odd and even programme—by as much as 40 per cent. Higher share of pollution benefits have come from a reduction in diesel cars.
This indicates reduced exposure to toxic pollution from vehicles on roads and close to the road side. It is estimated by the US-based Health Effect Institute that the maximum impact of vehicular pollution is up to 500 metres from the road side and 55 per cent of Delhi’s population live within that zone. This has serious public health implications. Studies by researchers of the University of California, Berkeley have shown that in Delhi, the pollution level on the road and close to the road side is at least 1.5 times higher and peaks 15 times higher than the ambient concentration. This programme has therefore contributed to the reduction in exposure to toxic fumes.
Graph 3: Particulate and nitrogen oxide load reduction from cars during odd-even scheme
Moreover, higher occupancy of cars due to car pooling and sharing has also reduced per capita toxic emissions of car users substantially. Shift to other modes can be even more substantial. This is a significant contribution of Delhiites to the pollution control efforts that needs to be respected and encouraged for a longer term solution.
Graph 4: Reduction in per capita emission of PM and NOxdue to car pooling car during odd and even programme
Vehicles need special attention as they are the second highest polluter in the city. Vehicles need to be included in emergency action: The EPCA status report has further citied the most recent study by IIT Kanpur on assessment of pollution sources to Delhi’s air has established that overall, vehicles are the second largest emitter of PM2.5 after road dust. It also shows that vehicles in Delhi not only have high primary emissions of particulates but also gases like nitrogen oxides that convert to nitrate particles in the air and add to the overall PM2.5 levels in the city. This further enhances the role of particulates.
Graph 5: Sources of PM2.5 in Delhi: Vehicles are second highest
Cars are also the emitters of toxic pollutants. For example, the Kanpur IIT study has shown that in different locations of their study in Delhi, diesel vehicles contribute hugely to PM2.5—from 60 per cent to 90 per cent of PM2.5 from vehicles. According to the California Air Resources Board, the number of excess cancer cases per million people due to lifetime exposure to diesel fumes is 300 as opposed to 29 for benzene that comes from petrol.
A significant study by the Health Effect Institute, Boston, published in Environmental Health Perspective recently, has found that particles from coal and diesel are more harmful than wind-blown dust. These increase ischemic heart disease-related deaths. This is dangerous as the global Burden of Disease for India attributes half of air pollution deaths to heart disease.
Graph 6: Contribution of fuels in vehicular pollution
Vehicles especially contribute to air toxins like polycyclic aromatic hydrocarbons (PAH) whose levels have been found to be high in Delhi. The IIT study has found high levels of PAH in different locations in Delhi. Total PAH levels (14 compounds) in winter is very high at 80 ng/m3 (annual standard is 1 ng/m3).
Even road dust is not harmless because of vehicular pollution. A 2015 study by the University and Birmingham has studied road dust in Mathura Road, Delhi, in the summer of June 2013 and found several elements, including copper, zinc, cadmium and lead in high concentrations. Tailpipe emissions and non-exhaust sources in vehicles like wear and tear of brakes, tyres and other auto parts are one of the major contributors along with industrial and biomass sources. To reduce the toxic effect of road dust, a further reduction in vehicular emissions and also environmental regulations for car tyres are needed.
Impact of odd and even number programme on air quality in other countries: Several countries have implemented odd and even formula as an emergency action to reduce peak pollution levels. Many of those programmes are more stringent in terms of duration, penalty and minimal exemptions. There are evidences of impact on air quality in those global cities.
With this programme, several cities have reported a wide range of benefits including reduction in air quality, reduced congestion, improvement in public transport ridership etc. Lowering of pollution levels have been reported in different cities. Paris for instance, which implemented this programme in March 2014 and repeated in March 2015, saw an 18 per cent reduction in traffic volume and 6 per cent in pollution levels. But Beijing that has a longer and a more stringent programme has shown 38 per cent reduction in PM10.
This indicates that even this percentage reduction is necessary and is possible in the short term to reduce smog peaks.
Overall benefit of the programme and our recommendation: Delhi is piloting its first ever-emergency action to reduce peak pollution levels. This is consistent with the best global practices. Vehicles that are second highest emitters in the city are responsible for very high exposure and health impacts. Smog peak reduction will need action on vehicles.
The first few days of the programme has already demonstrated that the peak pollution levels are lower than the normal smog peaks of the season – despite the adverse weather conditions.
In other countries, the duration of the programme is adjusted according to the severity and persistence of the severe pollution problem. Given the current pollution levels and adverse weather conditions, it is recommended that the Delhi government be allowed to complete the programme as planned. The government should be able to create the right template for the programme to be able to roll it out as and when needed. This is needed to protect public health. The lung of every third child is impaired in this city.
The other benefit of the programme is the reduced congestion that has further contributed towards the lowering of pollution. Emissions from vehicles caught in congestion increase two times due to idling and frequent acceleration and deceleration.
Reduced congestion has also improved the journey speed for all road users including car users. This saves time, fuel and stress. A study on traffic volume and speed survey carried out by the School of Planning and Architecture, New Delhi, at 11 locations during the first few days of the odd and even scheme in Delhi has found that due to lowering of traffic volume, the travel time has reduced by 35 per cent. This brings out the importance of reducing traffic volume.
Another important benefit of the programme is the improved efficiency of the public transport system—bus, auto and taxis that can now do more trips, more kilometers and carry more people due to freeing up of road space. This benefit will have to be sustained for a longer-term solution to the pollution problem in the city.
It is also important to note that the people of Delhi and neighbouring states are following the rule—it shows their cooperation and their desire to be a part of the solution to check this toxic and deadly air pollution. It is clear that we need to do more and not less to arrest air pollution and also make this scheme more successful, by reducing exceptions.
It also means that the government of Delhi must now work to greatly augment public transport so that the city can go car-free more often and as a general practice. This will be the big transition that the city needs for truly effective and durable action against deadly and toxic air pollution.
This status report clearly brings out the importance of taking emergency action when weather turns hostile in Delhi and traps pollution.
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