Worsening air quality justifies odd-even rule: Centre for Science and Environment3 min read . Updated: 01 Jan 2016, 05:01 PM IST
December 2014 had at least 3% of days in good and satisfactory categories, but December 2015 has none, says the Centre for Science and Environment
New Delhi: Air quality in the last two months of 2015 in Delhi was “worse" and this justified emergency actions such as the odd and even system, the Centre for Science and Environment (CSE) has said.
The CSE released the results of its analysis of the air quality data from continuous monitoring by the Delhi Pollution Control Committee (DPCC) to show how this winter pollution levels have worsened compared to last year. “
Both November and December 2015 show higher number of days in severe category, the worst category according to the National Air Quality Index. November had 73% of days in severe category against 53% in November 2014.
“December 2014 had at least 3% of days in good and satisfactory categories, but December 2015 has none. There has not been a single good air quality day this winter," the CSE analysis said.
It said that this justified emergency action such as the odd and even system that Delhi should pilot successfully to reduce toxic exposure during smog episodes. “If globally smog episode is defined as three consecutive days in the worst category of the air quality index, then the 2015 winter has already witnessed 11 such smog episodes. Such levels have lasted for 10 consecutive days as well," it said.
CSE said in its analysis that if with public support half of the cars are off the road, the total toxic load of particulate matter and nitrogen oxides can be halved from the car segment. “Total toxins, including benzene, PAH (polycyclic aromatic hydrocarbons) and other cancer causing substances can also be cut. More reduction is possible from diesel cars and SUVs (sports utility vehicles)," it said.
The CSE has urged that the odd and even number system be enforced with stringency to help develop alternative commuting practices and systems that can be sustained on a longer-term basis. “Given the level of choking pollution in the city and its health impact, people need to support to reduce their pollution footprint. Despite the exemptions granted to two-wheelers and women, voluntary participation is critical to reduce public health risk in the city," it said. “Delhi government should take this opportunity to improve the public transport services. Reduced congestion will be an opportunity to make the public transport perform more efficiently," it said.
The CSE said that a user of a single occupancy petrol car meeting Bharat Stage-IV standards can reduce per capita particulate emissions per kilometre by at least two times by using a CNG (compressed natural gas) bus, and the benefit will be higher if the shift is from cars meeting older emissions norms.
At the same time, it said that a user of single occupancy diesel car meeting Bharat Stage-IV can reduce per capita particulate emissions per kilometre by at least 40 times by using a CNG bus.
It said that the programme will also allow enormous fuel savings and mitigation of heat-trapping carbon dioxide (CO2) emissions. “Per capita CO2 emissions from a single occupancy petrol car can reduce by 15 times with shift to buses. Also, per capita CO2 emissions from a single occupancy diesel car can reduce by 13 times with shift to buses and SUVs to 22 times. This translates into substantial fuel savings," it said.
From a public health perspective, the CSE said that a study by the Indian Institute of Technology, Kanpur, has shown that in winter, vehicles are the second largest emitters of PM 2.5 after road dust, if both combustion sources and dust sources are considered. But vehicles are the top emitters among the combustion sources in winter.
Moreover, in different parts of Delhi, diesel four-wheelers are the source of at least 60-70% of PM 2.5 in winter. Several other studies in Delhi have shown how real-time exposure on roads and close to roadside are several times higher than background ambient levels, the CSE said.
Noting that vehicular emissions contain some of the deadliest toxins such as PAH and benzene, which are more in diesel emissions, the CSE said that serious health impacts have been associated with emissions from traffic. It said that a recently released study in the US by the Health Effect Institute has implicated PM 2.5 from diesel and coal with increased incidence of deaths due to ischemic heart disease. PTI