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Newsflash, Reading, 26/01/2022

Change in concentration of NO2, ozone, and particulate matter (PM2.5 and PM10) estimated at 80% SI score across 47 cities in Europe. NO2 and PMs are expressed by daily mean and O3 by daily maximum 8h-mean. Credit: London School of Hygiene & Tropical Medicine/Copernicus Atmosphere Monitoring Service

Government actions linked to road travel had the greatest impact on lowering NO2 concentrations and reducing the number of deaths, according to a new study released by the Copernicus Atmosphere Monitoring Service together with the London School of Hygiene and Tropical Medicine (LSHTM).

The Copernicus Atmosphere Monitoring Service (CAMS), implemented by the European Centre for Medium-Range Weather Forecasts on behalf of the European Commission with funding from the European Union, today announces its contribution to a study on air pollution levels in Europe during the first COVID-19 pandemic in spring and early summer 2020. The peer-reviewed research paper, led by the London School of Hygiene & Tropical Medicine, with contributions from CAMS and other leading institutions, examines the quantitative effects of reduced pollution levels and, for the first time to our knowledge, compared quantitatively the impact of different policy measures that were taken. The findings confirm earlier estimates that the decrease in pollution resulted in hundreds of avoided deaths across the cities.

The most important findings of the study were:

• The impact different policy measures had on air quality varied substantially among the measures taken.
• Measures restricting everyday life, such as school and workplace closure, had the strongest effects on air pollution levels. Restrictions around internal and international travel, however, showed much lower impact on local pollution levels.
• Scientists estimate a total of over 800 avoided deaths due to improved air quality resulting from the governmental measures taken to limit the spread of the SARS-Cov-2 virus.

Scientists involved in the study evaluated the association between various governmental measures and the decrease in the main regulatory pollutants including NO2, ozone, and fine particulate matter PM2.5 and PM10 across 47 major European cities and the associated short-term mortality during the onset period of the COVID-19 pandemic in Europe (February to July 2020).

Data from first COVID lockdown phase can help design more effective air pollution strategies

The main finding of the research was that the outcome differed substantially among the various interventions. For example, school and workplace closure, cancelling public events, and stay-at-home requirements had the strongest effects on reducing NO2 levels. On the other hand, restrictions on internal and international travel showed little impact on the local air pollution levels.

Importantly, the study quantified the changes in premature deaths from short-term changes in pollution across all cities. By using observed changes in daily concentrations of the pollutants studied, combined with assessment of people’s exposure, scientists estimate that a total of over 800 deaths were avoided with improved air quality resulting from the governmental measures taken to limit the spread of the SARS-Cov-2 virus. Paris, London, Barcelona, and Milan were among the top six cities with the highest number of avoided deaths.

Spanish, French and Italian cities had the largest decrease in NO2 of between 50% and 60% during the period, and this pollutant was substantially reduced across Europe. Reductions for other pollutants were less marked. This is expected because about half of NO2 emissions are generated by road transport, which was the most affected sector by government restrictions. Road transport is a much lower contributor to the total emissions of the other pollutants studied.

The groundbreaking research used surface level data provided by CAMS using an ensemble of regional air quality models to compare the concentrations of the main air pollutants obtained with two specific pollutant emissions scenarios, one corresponding to business-as-usual conditions and the other corresponding to a detailed estimate of emissions resulting from the actual governmental measures taken during the first lockdown, varying for each country, each day and for each of the main activity sectors (road traffic, industry…).

Lead scientists for the study used this unique air pollution dataset from CAMS and an advanced methodological approach to assess individual policy interventions in each city and their effects regarding decreasing pollution levels. While effects varied as expected, they observed a strong decrease in NO2, and to a lesser extent, fine particulate matter PM2.5, and PM10 in areas that enforced stricter lockdowns.

Vincent-Henri Peuch, Director of the Copernicus Atmosphere Monitoring Service (CAMS), comments: “This research benefits from a unique dataset provided by CAMS, which allows to compare as realistically and accurately as possible European air quality as it was experienced as a result of the COVID-19 measures and what would have happened under normal conditions. This overcomes many limitations of other studies, which compared for instance different years or different periods. The CAMS multi-model ensemble that has been used to generate this dataset has capabilities that have no equivalent in the world.”

“The findings are extremely significant as they consolidate the quantitative evidence that the COVID-related government measures had a direct effect on air pollution levels across Europe, particularly for NO2. Beyond the analysis of the mortality during the first months of the pandemic, this study could help shape future policy as the public health benefits of reducing pollution in our cities and the effectiveness of certain measures are clear to see,” he adds.

Rochelle Schneider, Honorary Assistant Professor in Geospatial Data Science at LSHTM, Visiting Scientist at ECMWF, and first author of the study says: “Government policies decided during the spring and early summer of 2020 gave us a unique opportunity to study a “real-life” scenario with lower air pollution levels. This paper conveyed strong messages on the potential of replicable, scalable, and collaborative research conducted with complementary expertise and knowledge from public health and tropical medicine universities, Copernicus, and meteorological institutes. Connecting expertise rapidly after and during the COVID-19 pandemic began has allowed us to estimate the health benefits from specific government measures. This, and other similar studies, can help drive the message that we definitely need to improve urban air quality for human health, and for the environment."

Antonio Gasparrini, Professor of Biostatistics and Epidemiology at London School of Hygiene and Tropical Medicine and senior author of the study says: “The lockdown during the first wave of the COVID-19 pandemic created immense health and social costs, however, it has offered unique conditions to investigate potential effects of strict policies to reduce pollution levels in urban areas. This ’natural experiment’ has given us a glimpse of how air quality can be improved by drastic public health measures that would be difficult to implement in normal times. The information can be important for designing effective policies to tackle the problem of pollution in our cities.”

Access the report here: https://www.nature.com/articles/s41598-021-04277-6