Covid-19 lockdowns have improved global air quality, data shows

Around the world, Covid lockdowns have led to improvements in air pollution. In northern India, the Himalayas were visible in the distance for the first time in a generation. And during the first nine weeks of the UK lockdown, nitrogen dioxide along London’s roads decreased by an average of 31% compared with the pre-lockdown period.

Non-essential shops in the capital reopened on 15 June but life and traffic pollution have still not returned to normal. Compared with 2019, decreases of more than 40% have been measured along roads in the City of London and Westminster, including the Strand and West End.

Q&A How to tackle air pollution

What are the best policies to reduce air pollution?

Most air pollution is produced by the burning of fossil fuels and waste, and this is the focus of the World Health Organization’s global recommendations:

  • Moving from coal and gas power stations and diesel generators to solar, wind and hydropower
  • Prioritise walking, cycling and public transport over cars in urban areas and shift to electric cars
  • Improve the energy efficiency of homes to reduce heating needs and avoid coal and wood burning inside
  • Promote waste reduction and use incineration only when unavoidable and when emissions controls are in place
  • Reduce the burning of stubble in fields upwind of cities
  • Create green spaces in cities to help remove some pollutants

In the UK, the government’s extensive research shows deterring polluting vehicles from city and town centres is by far the quickest, most cost-effective way to cut levels of nitrogen dioxide pollution, which are at illegal levels in most urban areas.

Other policies include:

  • Retrofitting of buses, heavy goods vehicles and taxis, which is the next most effective option
  • Scrappage schemes for older, polluting vehicles and subsidies for electric vehicles can also help

What are the best ways to avoid air pollution?

The solution to air pollution is stopping it at source but until that happens, experts including the British Lung Foundation (BLF) suggest the following:

  • Avoid spending long periods of time in places where pollution builds up, such as busy roads
  • If you travel on foot or a bike, using backstreet routes away from congested roads can cut exposure by half. Even on busy streets, cyclists experience less pollution than drivers
  • Some scientists recommend parents use covers on their buggies to protect infants
  • Go to work earlier, before the rush hour has begun and levels of pollution have built up
  • When air pollution is high and if you have lung condition such as asthma, reduce or avoid strenuous outdoor exercise, or do your exercise inside
  • There is very little evidence to recommend the use of face masks, according to the BLF

This builds on the improvements from London’s ultra-low emission zone. But there are emerging signs of a return to pre-lockdown pollution on some suburban roads.

The town of Horley, north-east of Gatwick, has recorded a 60% reduction in residential areas close to the airport fence and about 40% in a nearby children’s playground.

UK government measurement equipment near Heathrow detected a 46% improvement. The biggest reduction was 64%, recorded near the entrance to the Beech Street tunnel, which is closed to diesel and petrol traffic.

o Thanks to Timothy Baker, Louise Mittal and Anna Font, London Air and Imperial College London for discussion and coding assistance.

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