Theoretical Aspects – Nitrogen Dioxide

  • For the general public, the most prominent sources of NO2 are internal combustion engines burning fossil fuels. Outdoors, NO2 can be a result of traffic from motor vehicles.
  • The TROPOMI instrument, single payload onboard Sentinel-5 Precursor, retrieves operationally tropospheric and stratospheric NO2 column products. The TROPOMI NOdata products pose an improvement over previous NO2 data sets, particularly in their unprecedented spatial resolution (7×3.5 km2), but also in the separation of the stratospheric and tropospheric contributions of the retrieved slant columns, and in the calculation of the air-mass factors used to convert slant to total columns.

Bucharest NO2 Quantity Comparison: 2019 vs. 2020 Lockdown Period

(Satellite Imagery)

  • What better place to start our investigation rather than the area of our school? It’s also a great spot as our high school is located in the heart of Bucharest, with crowded crossings as well as a large park nearby.
  • Our approach consisted of using Sentinel EO Browser’s imagery facility that color codes the level of nitrogen dioxide emissions, from dark blue (insignificant quantities) to dark red (alarmingly huge emissions). In this way, we obtained images of the NO2 emissions in our school area from several days when Romania was under strict lockdown in 2020 and compared them to the data from the same time period of the year 2019.
  • As the pictures below prove, the emissions in 2020 (right column – “blue”, meaning very low values) decreased a lot from 2019 (left column – “red & green”, so higher levels of NO2).
  • Therefore, as we know NO2 can be a result of intense traffic, we conclude the imposed restriction did indeed have a positive impact on the emissions of such a dangerous gas.
March 17, 2019March 17, 2020
March 18, 2019March 18, 2020
March 21, 2019March 21, 2020
March 27, 2019March 27, 2020
March 28, 2019March 28, 2020
April 06, 2019April 06, 2020

Bucharest NO2 Quantity Comparison: 2019 vs. 2020 Lockdown Period

(Satellite Data Analysis)

References: The tropospheric NO2 vertical column density (VCD) time-series are calculated using the Version 4.0 Aura Ozone Monitoring Instrument (OMI) Nitrogen Dioxide (NO2) Standard Product (OMNO2) available at Nevertheless, the processing and plotting of data into charts are the result of our work. More information about the satellite and data can be found on the Theoretical Aspects page of our website.