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

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.

Effects of the COVID-19 pandemic on the environment, waste management, and energy sectors: a deeper look into the long-term impacts

“…A decision tree was established by primary constituents that were disintegrated from down-welling radiance spectra, which showed to be the highest durable methodology to obtain NO 2 readings. Improved differentiation of the NO 2 reading scale was derived with a partial least square regression model, and down-welling radiance measurements can be used to observe NO 2 levels continuously (Naethe et al 2020 ).…”

“…COVID-19 has made a great impact all across the world. Almost all countries are currently focusing their efforts to prevent the spread of COVID-19 disease by enacting policies such as the complete closure of public places (Liu et al 2021a , b ; Muhammad et al 2020 ; Naethe et al 2020 ). Though these policies or regulations may have a significant impact on the economies of most countries, they have some negative or positive effects on the environment, such as a substantial drop in the greenhouse gas emissions that have not been seen since World War II, as many industries in the world halted production and vehicle usage drastically decreased.…”

Reconstruction of Daily Courses of SO42−, NO3−, NH4+ Concentrations in Precipitation from Cumulative Samples

“…The visible drop in NO3 − concentrations observed at the LIB site in the past two years is likely to be due to the COVID-19 pandemic and related lockdowns with subsequent decreases in NOx in ambient air (precursors of NO3 − in precipitation), which was reported from many urban regions in Europe [62][63][64], including the Czech Republic [65]. A decrease in the number of cars operated in urban areas due to people being in home…”

Characterisation and Field Test of a Simple AvaSpec Array Spectroradiometer for Solar Irradiance Measurements at an Alpine Site

“…Further details on the application of spectroradiometers to PV technology are provided in Section S1 of the Supplementary Materials. Array spectroradiometers are also adopted in studies about air quality, photochemistry and atmospheric composition [12][13][14][15][16][17][18][19][20][21], by taking advantage of the spectral signature of some light-absorbing atmospheric compounds; phototherapy and medical dosimetry [22,23], in which the observation of the radiation spectrum is essential for assessing wavelengthdependent biological effects; measurement of the Earth's surface reflectance, e.g., to identify snow impurities [24]; and the monitoring of water quality and ecosystems [25][26][27]. Finally, array systems are not only useful in research but may also be introduced in industrial applications where reference solar spectra are required [28] or where spectroscopy-based techniques are employed for process control [29].…”