KEY POINTS

  • Satellite imagery shows significant decline in nitrogen dioxide emissions in Italy
  • Similar data was found in China at the peak of the coronavirus outbreak in the country
  • Reductions in activity in the hardest hit countries led to major reductions in air pollution

Satellite imagery captured a marked drop in nitrogen dioxide emissions over Italy. The drop in emissions coincides with the nationwide lockdown to prevent the further spread of coronavirus.

Air Pollution Decline

The European Space Agency's (ESA) Copernicus Sentinel-5P satellite captured the fluctuations in nitrogen dioxide emissions over Europe from Jan. 1 to March 11, 2020, the time when coronavirus began to spread to many European countries.

Interestingly, although not surprisingly, the data shows that the nitrogen dioxide emissions over Europe declined, particularly over the Po Valley in northern Italy where the emissions begin bright red in January, then, quickly dissipate towards the end of February when the first lockdowns were enforced. 

"Although there could be slight variations in the data due to cloud cover and changing weather, we are very confident that the reduction in emissions that we can see, coincides with the lockdown in Italy causing less traffic and industrial activities," Copernicus Sentinel-5P mission manager Claus Zehner said.

So far, Italy has been experiencing the biggest COVID-19 outbreak outside of China and the Italian government has since imposed a lockdown on much of the country. Evidently, the significant reduction in activities also resulted in marked declines in emissions from cars, factories and power plants.

Similarly, NASA and ESA satellites also captured dramatic declines in nitrogen dioxide coming from China in January when most of the activities in the country were halted due to the outbreak.

Nitrogen Dioxide

Nitrogen Dioxide falls under a group of highly reactive gasses known as nitrogen oxides. They primarily get in the air from the burning of fuels from sources such as cars and power plants and, may result in acid rain when they interact with the oxygen, water, and other chemicals in the atmosphere.

Apart from being harmful to ecosystems, nitrogen dioxide in the air is also harmful to health. When people breathe in air with high concentrations of nitrogen dioxide, it can cause irritations to the human respiratory system and aggravate respiratory diseases. Longer exposures may even cause people to develop asthma and even increase the vulnerability to respiratory diseases.

To combat these negative effects, the Environmental Protection Agency monitors the areas where air quality does not meet the national nitrogen dioxide standards so that the local governments can develop and implement plans to reduce nitrogen dioxide in the air and meet the standards.

Satellites such as Copernicus Sentinel-5P help monitor our atmosphere for such pollutants using the Tropomi instrument, which maps gasses such as nitrogen dioxide as well as other potentially harmful chemicals such as sulfur dioxide, methane, ozone, formaldehyde, and aerosols.

A deserted Via del Corso main shopping street in Rome, as Italy shut all stores except for pharmacies and food shops in a desperate bid to halt the spread of a coronavirus A deserted Via del Corso main shopping street in Rome, as Italy shut all stores except for pharmacies and food shops in a desperate bid to halt the spread of a coronavirus Photo: AFP / Alberto PIZZOLI