Temporal air quality (NO2, O3, and PM10) changes in urban and rural stations in Catalonia during COVID-19 lockdown: an association with human mobility and satellite data

Validity of air quality as a measure of human mobility. The COVID-19 context.

“…On the other hand, for Wakiso, only the correlation between air quality and movement in places of residence was statistically signi cant. These ndings are consistent with those of a previous study in Barcelona that found a positive correlation between the mobility in places classi ed as retail and recreation with nitrogen dioxide and coarse particulate matter (Gorrochategui et al 2021).…”

A model for simultaneous evaluation of NO2, O3, and PM10 pollution in urban and rural areas: handling incomplete data sets with multivariate curve resolution analysis

“…Considering that the principal emission source of NO 2 is traffic, it is reasonable that the four MCR-ALS resolved components evidenced a decline in the year-mode, corresponding to a diminution in April 2020 (under the strictest lockdown), compared to 2019 (under no pandemic) and 2018 (under no pandemic and no other traffic restrictions in Barcelona, such as the low emission zones (LEZs; LEZ -Àrea Metropolitana de Barcelona, 2020). Moreover, as stated in a previous study of the authors (Gorrochategui et al, 2021), in April 2020 a historical record of rainfall was registered in the control site of Observatory Fabra (8). Therefore, the highly rainy conditions of April 2020 favored the cleansing of the atmosphere, including NO 2 gases.…”

“…Also, the diminution observed in Z-mode profile in 2019, and to a greater extent in 2020, in the month of April was also produced when analyzing all the years, but to a lesser extent. This might be due to the fact that the traffic restriction policies were mostly implemented during the strictest confinement (from 14 March to 4 May in Catalonia) and were gradually removed in the de-escalation phases (Gorrochategui et al, 2021). Also, the extraordinary rainy conditions registered in April 2020 (Gorrochategui et al, 2021) were not registered for the rest of the months, making the NO 2 depletion less noticeable in the analysis of the entire year.…”

“…This might be due to the fact that the traffic restriction policies were mostly implemented during the strictest confinement (from 14 March to 4 May in Catalonia) and were gradually removed in the de-escalation phases (Gorrochategui et al, 2021). Also, the extraordinary rainy conditions registered in April 2020 (Gorrochategui et al, 2021) were not registered for the rest of the months, making the NO 2 depletion less noticeable in the analysis of the entire year. Regarding stations, the ones showing the higher contribution were the same three urban stations (i.e., Vall d'Hebron (1), Granollers (2) and Gràcia ( 6)) observed in the study of the month of April.…”

“…The selected air quality monitoring stations consisted of three urban stations (Gràcia, Vall d'Hebron and Granollers), one semiurban stations (Manlleu), and one control site (Observatori Fabra), all located in the province of Barcelona, and three rural stations, i.e., Juneda and Bellver de Cerdanya in the province of Lleida, and Begur (Costa Brava, NE Catalonia) in the province of Girona. More detailed information about the characteristics of the stations is provided in a previous air quality monitoring study by the authors (Gorrochategui et al, 2021). The NO 2 concentrations were measured by means of chemiluminescence according to the UNE method 77212:1993, using automatically operated MCV 30QL analyzers.…”