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. 2021 Jun:197:111092.
doi: 10.1016/j.envres.2021.111092. Epub 2021 Mar 27.

Assessment of CO2 and aerosol (PM2.5, PM10, UFP) concentrations during the reopening of schools in the COVID-19 pandemic: The case of a metropolitan area in Central-Southern Spain

Florentina Villanueva  1 , Alberto Notario  2 , Beatriz Cabañas  2 , Pilar Martín  2 , Sagrario Salgado  2 , Marta Fonseca Gabriel  3
Affiliations

Assessment of CO2 and aerosol (PM2.5, PM10, UFP) concentrations during the reopening of schools in the COVID-19 pandemic: The case of a metropolitan area in Central-Southern Spain

Florentina Villanueva et al. Environ Res. 2021 Jun.

Abstract

Public health authorities have been paramount in guaranteeing that adequate fresh air ventilation is promoted in classrooms to avoid SARS-CoV-2 transmission in educational environments. In this work it was aimed to assess ventilation conditions (carbon dioxide, CO2) and suspended particulate matter (PM2.5, PM10 and UFP) levels in 19 classrooms - including preschool, primary and secondary education - located in the metropolitan area of Ciudad Real, Central-Southern Spain, during the school's reopening (from September 30th until October 27th, 2020) after about 7 months of lockdown due to COVID-19 pandemic. The classrooms that presented the worst indoor environmental conditions, according to the highest peak of concentration obtained, were particularly explored to identify the possible influencing factors and respective opportunities for improvement. Briefly, findings suggested that although ventilation promoted through opening windows and doors according to official recommendations is guaranteeing adequate ventilation conditions in most of the studied classrooms, thus minimizing the risk of SARS-CoV-2 airborne transmission, a total of 5 (26%) surveyed classrooms were found to exceed the recommended CO2 concentration limit value (700 ppm). In general, preschool rooms were the educational environments that registered better ventilation conditions, while secondary classrooms exhibited the highest peak and average CO2 concentrations. In turn, for PM2.5, PM10 and UFP, the concentrations assessed in preschools were, on average about 2-fold greater than the levels obtained in both primary and secondary classrooms. In fact, the indoor PM2.5 and PM10 concentrations substantially exceeded the recommended limits of 8hr-exposure, established by WHO, in 63% and 32% of the surveyed classrooms, respectively. Overall, it is expected that the findings presented in this study will assist the establishment of evidence-based measures (namely based on ensuring proper ventilation rates and air filtration) to mitigate preventable environmental harm in public school buildings, mainly at local and national levels.

Keywords: COVID-19 pandemic; Particulate matter; SARS-CoV-2 transmission risk mitigation; School environment; Ventilation conditions.

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Conflict of interest statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Fig. 1
Fig. 1
Location of the metropolitan area of Ciudad Real (in the province of Ciudad Real in red) in Castilla la Mancha, Spain (A), and location of the surveyed school buildings (B). (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)
Fig. 2
Fig. 2
(a) Evolution of CO2 levels in the classroom with the maximum peak and average CO2 concentrations obtained in the study (measured from the beginning of the lectures at 9 h until the end at 14.45 h (local time) on October 9th, 2020). The dashed line corresponds to the threshold of 700 ppm from national recommendations. (b) Diagram of the classroom showing the location of openings for ventilation purposes and of the monitors for CO2 and particulate matter assessment.
Fig. 3
Fig. 3
(a) Evolution of UFP number concentrations in the classroom with the maximum peak and average UFP levels obtained in the study (Measured from 9 until 14 h, local time, on September 30th, 2020). (b) Diagram showing the geometry of the room with windows opened into the sand playground.
Fig. 4
Fig. 4
Evolution of PM2.5 and PM10 in the classroom with the maximum peak and average particulate matter levels obtained in the study. (Measured from 9 h until 14 h, local time, on September 30th, 2020). The dashed lines correspond to the threshold of 25 and 50 μg/m3 recommended by the WHO guidelines for PM2.5 and PM10, respectively (WHO, 2006).
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References

    1. Allen J.G., Marr L.C. Recognizing and controlling airborne transmission of SARS‐CoV‐2 in indoor environments. Indoor Air. 2020;30:557–558. doi: 10.1111/ina.12697. - DOI - PMC - PubMed
    1. Annesi-Maesano I., Hulin M., Lavaud F., Raherison C., Kopferschmitt C., De Blay F., Charpin D.A., Denis C. Poor air quality in classrooms related to asthma and rhinitis in primary schoolchildren of the French 6 Cities Study. Thorax. 2012;67:682–688. doi: 10.1136/thoraxjnl-2011-200391. - DOI - PMC - PubMed
    1. Aranda A., Díaz-de-Mera Y., Notario A., Rodríguez D., Rodríguez A. Fine and ultrafine particles in small cities. A case study in the south of Europe. Environ. Sci. Pollut. Res. 2015;22:18477–18486. doi: 10.1007/s11356-015-5165-4. - DOI - PubMed
    1. Baloch R.M., Maesano C.N., Christoffersen J., Banerjee S., Gabriel M., Csobod É., de Oliveira Fernandes E., Annesi-Maesano I., Csobod É., Szuppinger P., Prokai R., Farkas P., Fuzi C., Cani E., Draganic J., Mogyorosy E.R., Korac Z., de Oliveira Fernandes E., Ventura G., Madureira J., Paciência I., Martins A., Pereira R., Ramos E., Rudnai P., Páldy A., Dura G., Beregszászi T., Vaskövi É., Magyar D., Pándics T., Remény-Nagy Z., Szentmihályi R., Udvardy O., Varró M.J., Kephalopoulos S., Kotzias D., Barrero-Moreno J., Mehmeti R., Vilic A., Maestro D., Moshammer H., Strasser G., Brigitte P., Hohenblum P., Goelen E., Stranger M., Spruy M., Sidjimov M., Hadjipanayis A., Katsonouri-Sazeides A., Demetriou E., Kubinova R., Kazmarová H., Dlouha B., Kotlík B., Vabar H., Ruut J., Metus M., Rand K., Järviste A., Nevalainen A., Hyvarinen A., Täubel M., Järvi K., Annesi-Maesano I., Mandin C., Berthineau B., Moriske H.-J., Giacomini M., Neumann A., Bartzis J., Kalimeri K., Saraga D., Santamouris M., Assimakopoulos M.N., Asimakopoulos V., Carrer P., Cattaneo A., Pulvirenti S., Vercelli F., Strangi F., Omeri E., Piazza S., D'Alcamo A., Fanetti A.C., Sestini P., Kouri M., Viegi G., Baldacci S., Maio S., Franzitta V., Bucchieri S., Cibella F., Neri M., Martuzevičius D., Krugly E., Montefort S., Fsadni P., Brewczyński P.Z., Krakowiak E., Kurek J., Kubarek E., Wlazło A., Borrego C., Alves C., Valente J., Gurzau E., Rosu C., Popita G., Neamtiu I., Neagu C., Norback D., Bluyssen P., Bohms M., Van Den Hazel P., Cassee F., de Bruin Y.B., Bartonova A., Yang A., Halzlová K., Jajcaj M., Kániková M., Miklankova O., Vítkivá M., Jovsevic-Stojanovic M., Zivkovic M., Stevanovic Zarko, Lazovic I., Stevanovic Zana, Zivkovic Z., Cerovic S., Jocic-Stojanovic J., Mumovic D., Tarttelin P., Chatzidiakou L., Chatzidiakou E., Dewolf M.-C. Indoor air pollution, physical and comfort parameters related to schoolchildren's health: data from the European SINPHONIE study. Sci. Total Environ. 2020;739:139870. doi: 10.1016/j.scitotenv.2020.139870. - DOI - PubMed
    1. Bi Q., Wu Yongsheng, Mei S., Ye C., Zou X., Zhang Z., Liu X., Wei L., Truelove S., Zhang T., Gao W., Cheng C., Tang X., Wu X., Wu Yu, Sun B., Huang S., Sun Y., Zhang J., Ma T., Lessler J., Feng T. Epidemiology and Transmission of COVID-19 in Shenzhen China: analysis of 391 cases and 1,286 of their close contacts. medRxiv. 2020 doi: 10.1101/2020.03.03.20028423. 2020.03.03.20028423. - DOI - PMC - PubMed

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