key: cord-1048599-40e3c0lq authors: Briz-Redon, A.; Belenguer-Sapina, C.; Serrano-Aroca, A. title: A city-level analysis of air pollution, climate and COVID-19 early spread during the Spanish lockdown date: 2020-08-13 journal: nan DOI: 10.1101/2020.08.09.20171041 sha: 06ed29abf643172caf1457650cce57e3a4fbd4cf doc_id: 1048599 cord_uid: 40e3c0lq The COVID-19 outbreak has escalated into the worse pandemic of the present century. The rapid spread of the new SARS-CoV-2 coronavirus has caused devastating health and economic crises all over the world, with Spain being one of the worst affected countries in terms of confirmed COVID-19 cases and deaths per inhabitant. In this situation, the Spanish Government declared the lockdown of the country with the aim of flattening the epidemic curve. The variations of air pollution in terms of fine particulate matter (PM2.5) levels in 8 cities of Spain are analyzed here considering the effect of meteorology during the COVID-19 lockdown period (from March 15th to April 12th 2020). The results of the analysis show that the 4-week Spanish lockdown was not long enough to reduce the PM2.5 levels in all the cities considered. These reductions were less than those expected, despite the drastically reduced human activity. Furthermore, no associations between COVID-19 accumulated cases and PM2.5 exposure or environmental conditions (temperature, precipitation, wind speed, sunlight hours, maximum pressure) were found during the early spread of the pandemic. CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted August 13, 2020. . https://doi.org/10.1101/2020.08.09.20171041 doi: medRxiv preprint . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted August 13, 2020. . https://doi.org/10.1101/2020.08.09.20171041 doi: medRxiv preprint . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 13, 2020. (1 st Q), and 3 rd quartile (3 rd Q) at each of the different periods (normal, minor and major 156 lockdown) considered for the analysis Pollution data was downloaded from several regional and local web pages that provide this 159 official information for each city: Bilbao (Euskadi.eus, 2020); Madrid (Ayuntamiento de 160 Madrid, 2020); San Sebastián (Euskadi.eus, 2020); Santiago de Compostela (Xunta de 161 Galicia, 2020); Valencia (GVA, 2020); Valladolid (Junta de Castilla y León, 2020); Vigo 162 (Xunta de Galicia, 2020) and Vitoria (Euskadi.eus, 2020). PM2.5 data was obtained from 163 traffic stations in the cities (see Table 1 ) whose pollution levels were mainly determined by 164 traffic emissions (UK Department for Environment Food and Rural Affairs, n.d.). CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 13, 2020. . https://doi.org/10.1101/2020.08.09.20171041 doi: medRxiv preprint application of this European Standard is from 1 µg/m 3 (detection method limit) up to 172 approximately 120 µg/m 3 . Meteorological Agency (AEMET) through its API. Eight meteorological stations were Table 3 . Statistical summary of the meteorological variables considered for the analysis in 183 terms of mean value, 1 st quartile (1 st Q), and 3 rd quartile (3 rd Q) during the entire study period. . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 13, 2020. . https://doi.org/10.1101/2020.08.09.20171041 doi: medRxiv preprint 186 COVID-19 data was also downloaded from multiple local and regional webpages: Bilbao The R programming language (Team, 2020) was used to carry out the statistical analysis. CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted August 13, 2020. . https://doi.org/10.1101/2020.08.09.20171041 doi: medRxiv preprint terms capable of capturing non-linear relationships between the meteorological variables and 210 the PM2.5 level. The association between COVID-19 spread and the PM2.5 levels and environment was also 228 studied for all the cities included in the study except for the case of Valencia, of which daily 229 COVID-19 data is not available. Hence, the number of accumulated COVID-19 cases in each 230 city was modelled in terms of each of the environmental covariates available (temperature, 231 precipitation, wind speed, sunlight hours, maximum atmospheric pressure, and PM2.5 level) . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted August 13, 2020. is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted August 13, 2020. . https://doi.org/10.1101/2020.08.09.20171041 doi: medRxiv preprint These measurements show a gradual reduction of PM2.5 levels in 2020 with respect to those 259 of 2019, especially during the major lockdown (see Table 2 ). However, other factors such as . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted August 13, 2020. Table 5 . . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted August 13, 2020. . https://doi.org/10.1101/2020.08.09.20171041 doi: medRxiv preprint First, it is worth noting that the two precipitation-related variables were discarded, suggesting 285 the absence of an association between precipitation and PM2.5 values, and also that the 306 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted August 13, 2020. . https://doi.org/10.1101/2020.08.09.20171041 doi: medRxiv preprint The results shown in Table 5 suggest that the minor lockdown led to overall increases in 318 PM2.5 levels in the cities considered. Nevertheless, the full analysis of the proposed model 319 requires the consideration of the estimated city-specific coefficients, which were omitted in 320 Table 5 . In fact, overall city-specific effects, overall period (no lockdown, minor lockdown, is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted August 13, 2020. . https://doi.org/10.1101/2020.08.09.20171041 doi: medRxiv preprint PM2.5 pollution levels. Differences between marginal effects are statistically significant when 327 the associated confidence intervals do not overlap. Figure 3 shows the city-specific marginal 328 effects estimated by Eq. (1) for PM2.5 levels during minor lockdown, major lockdown, and 329 no lockdown. As can be seen, the differences between PM2.5 concentrations during the normal period, 336 minor, and major lockdown were not significantly different in many of the cities. However, 337 there was a rising trend in the minor lockdown PM2.5 levels in some cities considering 338 meteorological and week-day effects, especially in Bilbao and San Sebastián. Considering 339 that relative humidity was not included in the linear regression, these results may simply be 340 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted August 13, 2020. an artifact due to high relative humidity episodes that can improve the aqueous-phase CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted August 13, 2020. CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 13, 2020. . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted August 13, 2020. . https://doi.org/10.1101/2020.08.09.20171041 doi: medRxiv preprint Severe air pollution 618 events not avoided by reduced anthropogenic activities during COVID-19 outbreak Director-General's opening remarks at the media briefing on COVID-19 -11 622 Coronavirus disease (COVID-19) Pandemic [WWW Document ggplot2: Elegant Graphics for Data Analysis Ambient ( outdoor ) air pollution International trade linked with disease burden from 633 airborne particulate pollution The short-term effects of air pollutants on 636 hospitalizations for respiratory disease in Hefei, China Fine particulate air pollution and hospital emergency room visits for respiratory disease in urban areas in Beijing, China Risk evaluation of 643 environmentally persistent free radicals in airborne particulate matter and in fl uence 644 of atmospheric factors Calidade do Aire de Galicia [WWW Document Temporal 649 variations of ambient air pollutants and meteorological influences on their 650 concentrations in Tehran during Association between short-term exposure to air 653 pollution and COVID-19 infection: Evidence from China Assessing the 656 relationship between surface levels of PM2.5 and PM10 particulate matter impact on