Changes of NOx in urban air detected with monitoring VIS-NIR field spectrometer during the coronavirus pandemic: A case study in Germany

https://doi.org/10.1016/j.scitotenv.2020.141286Get rights and content

Highlights

  • A significant drop in urban NO2 emission was reported during the COVID-19 lock-down.

  • Simultaneous measurements of down-welling light model NO2 concentration

  • Inexpensive field spectrometer system reproduced the drop in NO2 levels.

  • Exploited wavebands in visible range model NO2 levels with promising accuracy

  • Monitoring NO2 as risk factor for COVID-19 may also include field spectrometers.

Abstract

The global outbreak of the coronavirus pandemic has led to a significant reduction of traffic and traffic-related urban air pollution. One important pollutant in this context is NO2. Sudden change in NO2 emissions related to reduction of urban traffic due to infection protection measures can be detected in Düsseldorf, Germany with continuous measurements of down-welling light with a RoX automated field-spectrometer. In comparison to a nearby reference instrument, a waveband around 590 nm was identified as significant for the retrieval in the VIS-NIR spectral range. A decision tree based on principal components which were decomposed from down-welling radiance spectra has been the most robust approach to retrieved NO2 values. Better differentiation of the NO2 value-range is achieved with a partial least square regression model. The results suggest that traffic-related changes of NOx pollution in urban air can be detected through continuous down-welling radiance measurements with inexpensive automated field-spectrometer systems.

Keywords

Air pollution
Field-spectrometer
Hyperspectral remote-sensing
Coronavirus

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