Regularisation of the 'odd-even' scheme will "reduce" its impact and it should only be used as an emergency measure, a green body today said, underlining the need for implementing alternative measures like "congestion pricing" to lessen the number of vehicles on roads to tackle air pollution.
The Energy and Resources Institute (TERI) which released an impact assessment study on the two-phases of odd-even scheme observed that as private cars have limited contribution in the PM2.5 levels, the scheme yielded only "marginal" reductions (4-7 per cent) during both the phases.
TERI observed that the impact of the scheme with respect to traffic counts, average speeds and air quality declined during the second phase in comparison to the first phase and the decline could be probably due to people opting for "second cars with alternative number plates, installations of CNG kits or enhanced use of taxis".
"The results of the two phases of odd-even scheme in Delhi suggest that it is useful only when high pollution episodes are expected. We do not see merit in regularising the scheme.
"A more sustainable approach for dealing with air pollution not only in Delhi but also in other metropolises would be congestion pricing, which is a far more effective option," Director General of TERI Ajay Mathur said.
Congestion pricing is based on a 'pay-as-you-use' principle with an aim to reduce the number of vehicles and in turn encourage modal shift by charging vehicles on entry in restricted zones and times. This can be complemented by providing exemptions to higher-occupancy vehicles.
TERI said that such a model has proved to be successful in cities such as Singapore, London, Sweden, Rome, Durham, Seoul, San Diego etc.
The congestion pricing scheme can be first tried out in different ways including, all across congestion pricing, identification of low-emission zones and road-wise congestion pricing, TERI said.
TERI also urged the government to ensure the earliest possible introduction of BS-VI vehicle and fuel quality norms, real-time monitoring and reporting of industrial emissions in NCR and the need for business models to convert agricultural wastes into energy using biomass gasification technologies.
Sumit Sharma, fellow at TERI, said that the measures,
which were taken, were more to control particulate matter rather than Oxides of Nitrogen (NOx). "We need multi-sectoral measures for the whole NCR to effectively reduce air pollutant levels, which calls for regular air quality management plans based on scientific studies," he said.
While TERI acknowledged that the scheme was successful in raising public awareness on air pollution as well as in improving traffic speeds, it also cautioned against the regularization of this scheme, saying the rule should at best be used as an emergency measure.
The body said that during phase II of the scheme, the general variation of PM 2.5 concentration due to daily changes in local emissions, meteorology and background concentrations (influences from outside Delhi) was 42 per cent.
The reduction achieved from the scheme during this phase seems too small (4 per cent) to be captured among the other more dominating factors.
TERI said that as in the case of other cities in the world that have tried out the scheme, people could look for alternatives by purchasing new or old cars which would, over a period of time, neutralise and negate the positive impacts.
"This is likely to happen as the public transportation system is not reliable and attractive enough to encourage the car users to shift to public transport.
"Hence, the odd-even scheme should be used only as an emergency measure when the pollution levels are expected to be very high like winters. Regularizing it or its frequent use may only reduce its impacts, unless public transportation is improved and sales of alternative vehicles are checked," it said.
TERI emphasized that air quality management plans should be based on scientific studies that are updated every 3-5 years and air-quality targets must be defined for each year and strategies must be enforced to achieve them in line with these plans.
TERI said that during phase-II of the scheme, the averaged PM2.5 concentrations at five locations were 1.4-4.3 times higher than prescribed 24-hourly standard, NO2 concentrations were 0.6-1.36 times the prescribed standard while PM10 levels were 1.8-4.0 times above the prescribed standard.
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Elaborating on the congestion pricing, TERI said the equity concern of the principle may be taken care of by carefully setting up the congestion charges and earmarking the revenues from congestion pricing for providing mass transport options in these zones as a public responsibility.
It said that car users in general are much richer than the non-car users and should pay for the additional pollution caused due to their cars.
"Congestion charges can be applied to more categories of vehicles and may not be restricted to only one category (like cars in the present Odd-Even system). This can certainly lead to much higher reduction in congestion and pollution levels in the city.
"It is expected that through congestion pricing, public transport will improve and attract more people as there will be a clear discouragement to use private vehicles. Contrary to the Odd-even scheme, the congestion pricing scheme can work throughout the year and provide year-long benefits of lower congestion and pollution levels and savings on fuel," TERI said.
It said that during phase-I (January, 2016), there was an increase of 25 per cent, 22 percent, and 27 per cent in PM2.5, PM10, and NOx concentrations respectively while in phase-II, the increase was 39 per cent, 26 per cent and 25 per cent, respectively.
The main reasons, TERI said for the increase were meteorological factors and background influences and during both the scheme periods, lower wind speeds and mixing height values led to relatively lesser dispersion of the pollutants, leading to higher concentrations.
"Odd-Even-II led to a reduction of 4 per cent in 24-hourly PM2.5 concentrations, largely because of the fewer number of cars on road. In other words, the concentrations could have been 4 per cent higher than those observed in absence of the scheme.
"The 4 per cent decrease in PM2.5 attributable to a 17 per cent decrease in car numbers is because the lower number of cars on the roads also reduce idling emissions from other category of vehicles (2-wheelers and buses) and reduce the amount of road dust," it said.
On medium term measures, TERI said that enhancement of public transportation systems and non-motorised options, E-mobility and demand control measures should be done while stack emission control devices should be maintained.
It said that industrial emission trading schemes and fiscal measures should be explored while standards for NOx and other important pollutants for industrial establishments should be put in place apart from ensuring 24x7 power supply in NCR to curb the use of Diesel generator.
