Air pollution mortality benefits of sustained COVID-19 mobility restrictions in Australian cities

Objectives: Emissions from road traffic, power generation and industry were substantially reduced during pandemic lockdown periods globally. Thus, we analysed reductions in traffic-related air pollution in Australian capital cities during March–April 2020 and then modelled the mortality benefits that could be realised if similar reductions were sustained by structural policy interventions. Study design: Satellite, air pollution monitor and land use observations were used to estimate ground-level nitrogen dioxide (NO₂) concentrations in all Australian capital cities during: (a) a typical year with no prolonged air pollution events; (b) a hypothetical sustained reduction in NO₂ equivalent to the COVID-19 lockdowns. Methods: We use the WHO recommended NO₂ exposure-response coefficient for mortality (1.023, 95 % CI: 1.008–1.037, per 10 μg/m³ annual average) to assess gains in life expectancy and population-wide years of life from reduced exposure to traffic-related air pollution. Results: We attribute 1.1 % of deaths to anthropogenic NO₂ exposures in Australian cities, corresponding to a total of 13,340 years of life lost annually. Although COVID-19-related reductions in NO₂ varied widely between Australian cities during April 2020, equivalent and sustained reductions in NO₂ emissions could reduce NO₂-attributable deaths by 27 %, resulting in 3348 years of life gained annually. Conclusions: COVID-19 mobility restrictions reduced NO₂ emissions and population-wide exposures in Australian cities. When sustained to the same extent by policy interventions that reduce fossil fuel consumption by favouring the uptake of electric vehicles, active travel and public transport, the health, mortality and economic benefits will be measurable in Australian cities.