How have the Covid pandemic and lockdown affected air quality in cities?

Air pollution in cities fell over the course of the first national lockdown, but now meets or exceeds pre-pandemic levels in 80 per cent of places studied.

Briefing published on 10 December 2020 by Valentine Quinio and Kathrin Enenkel

The pandemic has pushed air quality concerns down the agenda as national and local policymakers grapple with immediate healthcare and economic impacts. Important measures like Clean Air Zones (CAZs) have lost what priority they had, sometimes on the grounds that air quality has improved this year as a by-product of restrictions to control the spread of the virus.

This briefing finds that:

  • Although in cities and large towns like Glasgow, Warrington and Oxford, NO2 concentration levels more than halved during lockdown, not all cities and large towns experienced a significant improvement in air quality.
  • When restrictions were lifted, air pollution returned to its pre-pandemic levels in 39 of 49 cities and large towns studied, even though none had returned to previous levels of economic activity.

While many cities and large towns felt the benefit of a short-term reduction in air pollution, the long-term impact of the pandemic may be to make pollution worse as changed behaviour becomes entrenched even as economic activity is restored.

Figure 1: Evolution of NO2 concentration levels before and after the introduction of the first national lockdown

Urgent action is needed to prevent air pollution rising as Covid restrictions end

There are four main implications for policy that this analysis illustrates:

1. The pandemic does not lessen the need for action on air quality
2. Greater home working is not the answer to cleaner air
3. Policy needs to disincentivise car and other vehicle usage to improve air quality
4. Reducing car usage does not affect all pollutants equally

What needs to change

Air pollution is a killer. Research shows it causes 40,000 deaths a year. And a recent study suggested that 15 per cent of Covid deaths could be attributed to air pollution, through its harmful impact on cardiovascular and respiratory conditions. To reduce deaths in the future, the following needs to happen:

1. Accelerate the implementation of charging Clean Air Zones.

Those cities that have cancelled them should reverse their decisions, and those that have not brought proposals to consultation, despite poor air quality caused by traffic, should do so.

2. Encourage people to return to – and swap to – public transport once the pandemic is under control.

The implementation of charging Clean Air Zones will only be successful if people have alternatives to private vehicles. Expanding public transport usage must therefore be at the core of long-term strategies for cleaner air, which need to work hard to rebuild habits and confidence eroded by the pandemic.

3. Evaluate temporary active travel measures introduced during the pandemic and implement them if they are shown to be effective.

A number of cities have put temporary measures in place to encourage walking and cycling, such as the pop-up cycle lanes in cities like Manchester, Bristol and London. If these measures are shown to be effective in encouraging people to change behaviour then they should be made permanent, and other cities should take note of the lessons from these experiments.

4. Adopt World Health Organization (WHO) guidelines for PM2.5 in the Environment Bill.

The current limit for PM2.5 is more than twice as high as the one recommended by the WHO. In March 2020, as the pandemic began, MPs voted not to introduce the WHO guidelines, and the current Bill includes only a commitment to set a target by 2022, with no certainty over what this target will be. As the Bill continues its passage, its amendment should be the first of a number of steps needed to bring down PM2.5 emissions.

This research was conducted in partnership with CREA.

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