The European Space Agency recently launched an online map that shows global air pollution data collected from its Copernicus Sentinel-5P satellite. The map shows averaged nitrogen dioxide concentrations using a 14-day moving average. Fluctuations in emissions as well as changes in conditions due to sunlight, temperature, and wind affect the day-to-day levels of NO2. The 14-day average helps to eliminate short-term effects such as weather conditions and cloud cover in order for users to see regional pollution level trends. NO2 pollution can be traced to industrial activities, vehicle traffic, and power plants. NO2 acts as an irritant and elevated levels can cause respiratory problems in humans by inflaming the linings of the lungs.
To see changes over time, a simple function at the bottom of the map lets users scroll backwards and forwards in time to see NO2 levels. Users can zoom into a particular area for a more detailed look at NO2 levels.
For example, the two maps below show the changes on NO2 levels during the period before Italy entered a country-wide lockdown and during a period in the middle of the country’s lockdown due to the COVID-19 pandemic. NO2 levels across the region shown dropped as more areas enforced “stay at home” orders and air traffic diminished.