The 15-day odd-even car experiment turned Delhi in to the petri dish for the largest road apportionment experiment ever tried in a city in India. The audacious attempt by the Aam Admi Party to redirect public outcry over city’s dirty air in to an actionable, but singular agenda for citizens and the subsequent large-scale mobilisation of people raised expectations of a visible and substantial outcome at the end of the fortnight.
Conversion of public sentiment in to a mobilised citizenry requires rhetoric (even hyperbole at times) and a simple binary messaging — odd/even or nothing. Arvind Kejriwal, who had earlier iconized Jan Lokpal bill to whip up an anti-corruption platform, did well this time around too in mobilising collective civic action like it’s been rarely witnessed in the capital. But, the raised expectations of citizenry had to come to terms with the science of air-pollution. After all, the odd-even experiment was only a single-pronged temporary attack against a cocktail of pollutants, their complex chemistry and a lack of clarity over data between various agencies that measure pollutants — there is still no unanimity over which source causes how much pollution in Delhi.
This much was bound to be a truism despite the complexity of managing air-pollution — when you shut off a polluting source, even if for fortnight, the load of pollutants being spewed in to the atmosphere goes down. If nearly half the cars in Delhi remained shut down for a fortnight the pollution load being added to the ambient atmosphere from cars had to be lower than business as usual. Another truism is: if you halve the number of cars on the road you are bound to have less congestion on the roads. The latter truism is easier felt and did not require proof beyond driving experience for most.
The Centre for Science and Environment (CSE) presented calibrated, but positive answers to the question of how pollution had been impacted by the scheme, while the Delhi state government took the technically specific plea that the purpose was to reduce peak level pollution loads. Answers and analysis from other agencies and monitoring bodies varied. For good reason. But more of that later.
Both particulate and nitrogen oxide load from cars reduced substantially during the odd-even programme by as much as 40%, the court was informed based on CSE’s analysis. IIT Kanpur’s study was pointed to note that vehicles were the second highest contributor to particulate matter below 2.5 microns. But 31% of the load out of this comes from two-wheelers which were not covered by the scheme. Only cars were. The decongestion of roads improved efficiency of public transport. During the days smog prevailed it was not as intense as it could have been even though the weather conditions were worse than on days in November and December when all cars were on the road – peak load of pollutants in the atmosphere had been arrested some bit.
The calibration came in the prescription for future action. CSE said, “This is an opportunity in the city to create and test out the plan for augmented public transport services which can be sustained even after the programme is over. This will help Delhi catalyse longer-term solutions to the mobility crisis that is worsening the air pollution impacts.”
“It is one out of a menu of emergency actions — it is temporary and deployed only when there is an emergency. Naturally it’s not done during monsoons when rains wash away the pollutants faster. Cities like Beijing deploy the off-road policy more stringently and other emergency actions as well during such emergencies to get better results,” explains Anumita Roy Chowdhury, executive director of CSE.
CSE and other expert groups have long pushed for a much wider set of actions – some short term in times of emergency and some structural and long term - to help arrest deterioration in Delhi’s air. From congestion taxes to parking rationalisation, enhanced and integrated public transport systems to regulating other sources of pollution than vehicles. Kejriwal had picked up one small prong to spike the city in to action with. Earlier governments had avoided this as well as the more structural ones. The idea of a congestion tax in Delhi has been in place for more than half a decade but successfully brushed aside over years.
Some scientific facts were bound to limit the stand-alone short-term experiment’s end-purpose – making Delhi’s air less dangerous to breath. When an engine burns fuel it emits several kinds of harmful chemicals. Each chemical acts differently once discharged in the atmosphere. Some get dispersed further than others. Some are much more dangerous than others for human health even in small doses and some can be disproportionately harmful in high doses. Some break down or disappear faster than others. Some interact with other chemicals to cause disproportionate harm or create new chemicals in disproportionate levels — called secondary polluting chemicals which act like completely different animals.
And the life of these pollutants itself is dependent on factors such as moisture and ambient temperatures in a part of the city, which are impacted by the larger weather phenomenon the region is undergoing. A cold inversion can ensure pollutants stay settled down near the surface like a blanket choking the city. Higher ambient temperatures and moisture can alter how other toxics perform.
Take the case of ozone. It’s a deadly pollutant when floating close to ground. It is formed when family of nitrogen oxides (emitted from vehicles and other sources) mixes with volatile hydrocarbons (also originating from burning fossil fuels) in high temperatures. Ozone is a much more harmful chemical and it disperses wider and tends to migrate towards greener areas of the city — usually also the richer parts in case of Delhi.
To add to this complexity is the business of measuring pollution in the city’s air. It’s dependent on sampling – putting up meters that measure pollutants at specific spots at specific times or interval of times in parts of the vast city. Data can be measured and compared over time only if the method of measuring, the technology used to measure and the points where samples are taken remain consistent. In much of the rest of country there is no system in place to measure pollution. In Delhi there are multiple agencies and research organisations doing so through different methods. During comparisons over the fortnight measurement of exposure of people to the polluted air was often compared with measurements of the load of pollutants in the ambient air. They are correlated but not comparable.
For anyone critically assessing impact of this chemical cocktail on people's health she has to go beyond assessing just the ambient pollution load and inspect actual exposure of people to these chemicals in the air. That gets decided by the nature of the city planning. Do people live closer to roads and polluting sources? The impact on public health is disproportionately higher when people live closer to roads — within 500 meters — than those who live further away. It takes prolonged exposure to some pollutants — such as particulate matter (technically these are complex amalgamated particles called aerosols) and a shorter exposure to other more toxic chemicals that can lead to health problems.
In sum, you can take out 100,000 cars off the city roads for a fortnight but the net consequence of this on public health would depend in the least on the following parameters – the vintage and health of cars that went off-road, the distance they would have run otherwise and in what traffic situations, what mode of transport did the people use as replacement, how did the weather fare that fortnight and the physical planning and mobility plans of the city itself.
Against this, people in general wondered and the courts at times asked, tell us if removing the cars from the roads had a positive impact in reducing air pollution or not. The short answer had to be yes. But if asked by how much public health had been safeguarded by the measure — the answer would necessarily have to be full of caveats.
Congestion came down temporarily. This was an inevitable positive outcome of the experiment but in the long-term decongestion too would require overhauling public transport.
The last attempt, to apportion more road space to public transport, though at a much smaller scale, was to set up the bus rapid transport (BRT) system on a central artery of the capital. It failed due to technical hitches but got discredited as much due to lack of political support and car-owner’s complaints. Kejriwal found the right language to not say as much but make same people give up road-space to public transport at a city-wide level, albeit temporarily.
He has given a positive direction to the building anxiety in the city over air pollution. He has partly taken back the space for executive action from the judiciary by trying to work with it. Time would tell and sociologists can predict if it has raised expectations of the citizens from Kejriwal to deliver on the more structural changes that require government action and not civic mobilisation or only helped ease some pressure on his government to act this rather warm and easier winter.
Delhi is not the first city that got spurred in to action suddenly by extreme air pollution events. Across centuries and geographies cities and countries have acted exactly the same way to urban air pollution crisis (see box). The cities that have won the battle against air pollution did so with more long-term answers. But the complexity of the science of air pollution and that of politics ensures no other city in India can try the same experiment against air pollution and expect the same results.