Nitrogen Dioxide (NO2) is a well-known pollutant – primarily produced by the burning of fossil fuels and is closely linked to road traffic. I.e the more petrol and diesel cars on the road the greater the levels of NO2. NO2 is associated with a wide variety of respiratory problems and has a direct impact on human health, especially the very young and very old. For this reason, tracking and understanding NO2 is critical to human health.
Recently there have been fascinating studies showing just how strong the correlation is between nitrogen dioxide in the atmosphere and human behaviour is, both in Europe and across China, with sudden changes around the world during and after the COVID-19 lockdown.
A study published over a decade ago, and using data going back to 1994 have shown that Chinese Holiday results in a dramatic decrease in NO2 and other related pollutants. A more recent study in July 2020 using satellite data shows how NO2 levels drop dramatically during the Lunar New Year.
On the day of the Lunar New Year, there is a drop of around 40% of NO2, with levels slowly returning over the next few days. This difference was more pronounced in 2020 due to the lockdown, but the effect is still visible every year.
The image below shows the No2 levels relative to the Lunar new year, with a massive drop on the day itself. It is interesting to note that while the 2020 lockdown showed a more pronounced effect in the days after the new year, on the day of the new year there was no real difference.
There is a variety of satellite technology used to map NO2, including:
- Tropospheric Monitoring Instrument (TROPOMI) on ESA’s Sentinel-5 satellite.
- Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite