A report by environmental group Ecologistas en Acción (Environmentalists in Action), Effect of the COVID-19 crisis on urban air quality in Spain, states that the drastic reduction in traffic is translating into an unprecedented improvement in air quality, which is currrently far below legal limits and WHO recommendations.

A report by environmental group Ecologistas en Acción (Environmentalists in Action), Effect of the COVID-19 crisis on urban air quality in Spain, states that the drastic reduction in traffic is translating into an unprecedented improvement in air quality, which is currrently far below legal limits and WHO recommendations. Atmospheric instability throughout March has also contributed to this improvement.

Restrictions to traffic, in place as a consequence of the current state of alert, caused a pronounced decrease in nitrogen dioxide between March 14th and 31st in the country’s main cities, as a consequence of the reduction to motorised traffic.

The environmental group stresses that this decrease in pollution has occurred in the context of an extreme situation, which is by no means desirable, and is causing deaths and serious difficulties to a large number of people.

First of all, Ecologistas en Acción wish to manifest their solidarity with everyone suffering from this pandemic and its consequences, as well as the essential public services who are on the frontline of this health and social emergency.

The report written by Ecologistas en Acción analyses the official data on nitrogen dioxide (NO 2 ) collected from 125 measuring stations spread across 24 cities in Spain during the month of March 2020, as well as in the previous ten years. It therefore offers a current picture of urban air quality in the last month, before and after the declaration of the state of alarm and the confinement measures.

Among the main conclusions of this report, the following stand out:

Since the declaration of the state of alarm on March 14th atmospheric pollution levels caused by nitrogen dioxide (NO 2 ) in the most important Spanish cities have been drastically reduced, a reduction that stands at 55 % of current pollution levels for this time of year, over the last decade.

) in the most important Spanish cities have been drastically reduced, a reduction that stands at 55 % of current pollution levels for this time of year, over the last decade. There is a generalised improvement in air quality, both in city centers as well as the outskirts; the measures taken to limit traffic are equally generalised. A certain difference in registered pollution persists; it is higher in traffic-oriented stations than in urban background stations.

NO 2 levels registered during the state of alarm are the lowest of the decade for the second half of March, in all the cities analysed. What is more, they remain far below the limit value and the WHO annual guide, when normally this threshold is frequently exceeded in March.

levels registered during the state of alarm are the lowest of the decade for the second half of March, in all the cities analysed. What is more, they remain far below the limit value and the WHO annual guide, when normally this threshold is frequently exceeded in March. On a national scale there appears to be less pollution decline in the cities of the Cantabrian seaboard, perhaps due to unidentified meteorological factors. On the other hand, cities on the Mediterranean coast display the greatest descent in NO 2 levels, on occasion even falling to levels that are more characteristic of rural background stations.

levels, on occasion even falling to levels that are more characteristic of rural background stations. The heavy rains and atmospheric instability prevailing in March have also contributed significantly to an improvement in general air quality.

Nitrogen dioxide (NO 2 ) is a pollutant typical of car exhaust tubes (as well as industrial and domestic boilers), which is why its evolution is directly linked to emissions from motorised traffic, which is mainly produced inside cities and is the single most important influence on urban air quality.

) is a pollutant typical of car exhaust tubes (as well as industrial and domestic boilers), which is why its evolution is directly linked to emissions from motorised traffic, which is mainly produced inside cities and is the single most important influence on urban air quality. Every year NO 2 causes approximately 7,000 premature deaths, according to Instituto de Salud Carlos III and the European Environment Agency. It is an irritant gas that exacerbates respiratory diseases and weakens resistance to infection; consequently, its drastic reduction is good news, in the context of the current sanitary emergency.

causes approximately 7,000 premature deaths, according to Instituto de Salud Carlos III and the European Environment Agency. It is an irritant gas that exacerbates respiratory diseases and weakens resistance to infection; consequently, its drastic reduction is good news, in the context of the current sanitary emergency. Although not included in this report, there has been a remarkable decrease in suspended particles (PM10 and PM2.5), as well as ozone levels, in the second half of March. The drastic fall in nitrogen dioxide (NO 2 ) emissions, the main ozone precursor pollutant, may have contributed to this circumstance, together with the unstable, rainy weather.

) emissions, the main ozone precursor pollutant, may have contributed to this circumstance, together with the unstable, rainy weather. The COVID-19 crisis proves that the structural reduction of motorised traffic, together with shifts in mobility patterns, are the best resource for the reduction of air pollution in cities, notwithstanding the fact that this has occurred in the context of an extreme and wholly undesirable situation that is causing deaths and serious problems to many people.

Ultimately, this dramatic situation caused by the coronavirus pandemic verifies what Ecologistas en Acción and the scientific community as a whole have argued for some time now: a reduction in urban motorised traffic has a clear effect on the decrease of pollution, which in turn leads to a significant improvement in public health.

Once we emerge from this tough crisis, from confinement and the limitations to our freedom of movement, this conclusion should guide urban mobility policies, by establishing ambitious low emissions zones, restoring public transport and promoting cycling and pedestrian traffic as alternative means of transport, instead of private motor vehicles.