Sharp drop and slow recovery of NO2 levels
Figure 1 depicts the evolution of NO2 levels over 5 regions which were strongly affected by the COVID-19 crisis. The figure shows the relative reduction in NO2 in 2020 compared to the observations over the same period in 2019, averaged for all big cities within the region.
As can be seen, average NO2 reductions of up to 50% were observed over Chinese cities at the peak of the crisis, whereas in India, Europe, North and South America, NO2 reductions ranged between 20 and 35% in the first weeks after the initiation of lockdown measures. Partial relaxation of the COVID-19 measures led to a gradual increase in NO2. In China, it took only 2 months to reach the NO2 levels of 2019, whereas in many other cities around the world, NO2 columns remained lower than in 2019 for more than 4 months.
In Europe and North America, the emergence of a second COVID-19 wave and the subsequent tightening of the restrictions in October 2020, led to new NO2 reductions, which are however still relatively weak compared to the first pandemic wave.
Great deal of attention for impact of coronavirus on NO2 pollution
Our results were published in peer-reviewed scientific literature (Bauwens et al.: Impact of coronavirus outbreak on NO2 pollution assessed using TROPOMI and OMI observations, Geophys. Res. Lett., 47, e2020GL087978, https://doi.org/10.1029/2020GL087978, 2020) and in press releases like:
- TROPOMI observes the impact of the corona virus on air quality in China
- Satellites see a worldwide decrease in nitrogen dioxide pollution as a result of the COVID-19 crisis, China shows first signs of economic recovery
- COVID-19: Air pollution returns as lockdowns are lifted
- Is the global COVID-19-related drop in NO2 pollution coming to an end? (ESA)
- Air pollution in a post-COVID-19 world (ESA)
The topic attracted a great deal of attention from the local and international media:
- VRT: Bonus voor de luchtkwaliteit door corona is bijna helemaal weggesmolten
- RTBF: Quand les effets du Covid-19 se voient depuis l'espace
- TheScientist: COVID-19 Lockdowns Will Have Negligible Effect on Climate Change
- Physics today: Coronavirus shutdowns clear the air, temporarily
Ongoing work on anthropogenic pollutants
This research is ongoing. The unanticipated atmospheric composition experiment caused by the pandemic constitutes a unique opportunity to test our understanding of atmospheric processes driving the abundance of anthropogenic pollutants.
Ongoing modelling work is being conducted in order to disentangle the impact of COVID-19 from the effects of meteorological variability and long-term emission abatement policies.