Car-free day sees drop in air pollution

Delhi-based non-profit Centre for Science and Environment (CSE) has found a dramatic reduction in the exposure levels to particulate pollution on the stretch from Red Fort to India Gate during the car-free day that was observed on Thursday. Pollution levels were 60 percent lower than the levels observed in the same place, at the same time, on Wednesday.

This observed reduction is further supported by the city-wide official ambient monitoring done by the Delhi Pollution Control Committee. This has shown an overall drop of 45 percent in PM2.5 level in the city. The car-free initiative, as well as the low traffic load on the national holiday of Dussehra, has helped lower the pollution levels and toxic exposure in the city.

“This initiative of the Delhi government has only helped to prove how the growing car numbers in Delhi aggravate toxic pollution; if these numbers are controlled, pollution can be lowered significantly. Though this event has been planned for one road stretch a day every month to help build public awareness, this will need simultaneous action to restrain car usage on a daily basis for real change. Otherwise, this will get reduced to only a symbolic gesture. Restraint on cars can help to save lives and protect the lungs of our children,” says CSE executive director Anumita Roychowdhury.

CSE has carried out real-time exposure monitoring on the stretch from Red Fort to India Gate that was earmarked for the half-day car-free event. This monitoring is different from the ambient monitoring that the government does. Exposure monitoring captures the pollution on road and roadside that is influenced by the direct emissions from vehicles within our breathing zone. This is normally higher than the ambient level. The exposure monitoring on the road was carried out by CSE first on October 21 -- a regular day -- and during the car-free event on October 22.

October 21, a regular day: On this day when the road stretch from Red Fort and India Gate had high traffic volumes, the PM10 level was as high as 750 microgrammes per cubic metre (cu m) and the PM2.5 level was 689 microgrammes per cu m. This was three times higher than the average ambient PM2.5 level in the city.

October 22, car-free day: The dramatic drop in exposure to pollution – as much as 60 percent: During the morning hours (7 am to 12 noon) when the car-free event was on and there were few cars on the road the PM10 level was 310 microgrammes per cu m and the PM2.5 level was 265 microgrammes per cum m. This shows a dramatic drop of 59 percent in PM10 levels and 62 percent in PM2.5 levels compared to the previous day. This was still two times higher than the city-wide PM2.5 level on Friday. Few cars were still running on the targeted stretch.

Hourly variation in pollution levels on car free day shows winter condition setting in. The hourly pollution data on car free day shows that though the overall levels had declined compared to the previous day, the level in the morning was higher than around noon. At 7 am when the car-free event commenced, the hourly average of the PM2.5 level was 384 microgrammes per cu m. But by noon it dropped to 148 microgrammes per cu m – as much as 61 percent drop. Cool and calm weather condition in the morning hours had trapped more pollution. By the noon it dissipated. This just foreshadows the winter pollution crisis that Delhi faces. Delhi needs urgent winter pollution action plan to ensure that Delhi does not see a repeat of the alarming winter pollution like the last year.

City-wide official ambient monitoring done by the Delhi Pollution Control Committee shows significant reduction in overall ambient pollution level: CSE has also analysed the DPCC ambient air pollution data of the mornings of October 21 and October 22 for four monitoring locations – Mandir Marg, Punjabi Bagh, R K Puram and Anand Vihar -- and found 45 percent drop in the average PM2.5 level in the city. October 22 being a national holiday on the occasion of Dusshera there was a significant reduction in overall traffic volume in the city. Official monitoring also shows higher pollution in the morning hours than in the noon.  

Half of the particulate load from the transport sector in Delhi comes from personal vehicles

According to the non-profit, growing dependence on personal vehicles – cars and two-wheelers – further aggravate the pollution problem. The personal vehicles already contribute half of the total particulate load from the transport sector in Delhi. It is getting worse with an increase in some diesel cars and SUVs. Compared to petrol cars particulate and nitrogen oxide emissions from diesel cars is just double. Bigger diesel SUVs pollute even more. Diesel SUVs emit 80-90 percent more particulate matter and 60 -90 percent more nitrogen oxide compared to diesel cars. Increase in diesel cars is also increasing lung cancer risk in the city.

Immediately link and scale up metro-bus-autos/taxis-walk and cycle: This is needed immediately to connect door steps of people with their destinations for effortless movement without the car. Connect each and every neighbourhood with efficient and reliable public transport service.

Provide safe and barrier free walking and cycling infrastructure: Redesign roads and road network to give safe and priority infrastructure to walkers, cyclists and public transport users.

Adopt parking policy and taxation measures to restrain car usage: Limit legal parking areas across the city and demarcate them on the ground. Impose a high penalty for illegal parking on public space. Charge high parking charges and also price residential parking in public spaces. Impose higher taxes on cars for their congestion and pollution impacts. Use the revenue to build public transport.