Do Car Bans Actually Mitigate Air Pollution?

By Tali Trigg, Scientific American

13 February 17

Recent measures in Paris and New Delhi yield mixed results

n recent months, several cities from Paris to New Delhi have resorted to banning cars to improve worsening air pollution. While some see this as a long-term solution, others question if it is no more than an emergency band-aid on a profusely polluting limb. 

Air quality can be a hard thing to ascertain, but with increasing air quality monitoring, not to mention social media activity on the topic, air pollution is worsening in many cities, and nitrogen oxides (NOx) from the transport sector are a major culprit, with deleterious effects including asthma, heart disease, and cancer. 

Transport is not alone to blame; in many cities there are nearby power stations and/or industrial production, which contribute a large share of pollution, but these are understandably harder for politicians to shift overnight. So when citizens demand for action, they sometimes get it, but the question is: is it the right action?

In cities like Beijing, a bogeyman is often thrown under the wagon to appease citizens, such as street vendors, who despite unctuous smells do not actually contribute much to ambient air quality. In all cases, however, topography matters. If your city has the unfortunate bowl shape of Los Angeles, Mexico City, or Kathmandu, then it will always be harder dealing with poor air quality. Of course, that is not a reason for passivity, but action.

So, what can be done? Well, there are two broad paths really. Either you ban cars as an emergency measure. Or, you lay the groundwork for walking, cycling, and public transportation, so that car-free or car-optional lives become reality.

While car-free days have the additional and substantial benefit of increasing public awareness of sustainable transport, it will not be enough to solve dangerous air pollution in cities. Rather, long-term solutions include: permanently banning diesel cars — a carcinogenic fuel option, long overdue for reform, as well as improved access to buses, metro rail, walking, cycling, and especially connectivity between options. Other than that, forget about technology-driven quick-fixes that only politicians would choose — looking at you, electric buses. Sure, they have positive effects, but are not comprehensive nor serious near-term solutions to a very serious problem.

Finally, let’s not forget about proportionality. While passenger cars get a bad reputation, let’s not forget that the freight sector accounts for a significant portion of urban air pollution while accounting for a small part of the overall vehicle fleet. Sounds like an opportunity to me. And speaking of proportionality, consider this: in New Delhi, 14% of travel demand is carried by cars, but 80% of spending is dedicated towards it. Go figure.