Author(s)

Thomas Bourdrel^1*, Leo Zabrocki^2*, Nathalie Compte³, Bert Bravenboer³, Romain Decours⁴, Hélène Pelerin⁵, Laure De Decker⁶, Laurence Le Jumeau de Kergaradec⁷, Matthieu Lilamand⁸, Claire Roubaud Baudron⁹, Bertrand Fougère¹⁰, Rachid Mahmoudi¹¹, Benoit Schorr¹², Georges Kaltenbach¹², Thomas Vogel¹², Vincent-Henri Puech¹³, Fréderic Blanc¹, Marie-Abèle Bind¹⁴

¹ICube Laboratory, UMR 7357 and CNRS, University of Strasbourg, Strasbourg, France.
²Paris School of Economics, EHESS, Paris, France.
³Geriatric Department, Universitair Ziekenhuis Brussel, Bruxelles, Belgium.
⁴Service de Gériatrie, Centre hospitalier départemental de Vendée, La Roche Sur Yon, France.
⁵Unité de recherche clinique, Centre hospitalier départemental de Vendée, La Roche Sur Yon, France.
⁶Service de Médecine aigüe gériatrique Centre hospitalier universitaires de Nantes, Nantes, France.
⁷Service de Gérontologie, Centre hospitalier universitaires de Nantes, Nantes, France.
⁸Service de Gériatrie Assistance publique Hôpitaux de Paris (APHP) Nord, Paris, France.
⁹Unité Post Urgences Gériatriques Centre hospitalier universitaire de Bordeaux, Hôpital Pellegrin, Bordeaux, France.
¹⁰Department of Geriatric Medicine, Centre hospitalier universitaire de Tours, Tours, France.
¹¹Médecine Interne Gériatrie et Biologie du Vieillissement, Centre hopitalier universitaire de Reims, Reims, France.
¹²Pôle de Gériatrie, La Robertsau Geriatric Hospital, University Hospital of Strasbourg, Strasbourg, France.
¹³European Centre for Medium-Range Weather Forecasts, Copernicus Atmosphere Monitoring Service, London, UK.
¹⁴Biostatistics Center, Massachusetts General Hospital, Boston, MA, USA.

Because the elderly account for 80% of deaths from COVID-19 and they may be more vulnerable to air pollution, in this retrospective study we aimed to explore individual and environmental risk factors for COVID-19 mortality in the geriatric departments of seven European University hospitals, between February and May 2020. Long-term exposure to air pollution was estimated through annual pollutant concentrations at the residential address over the last two years. Short-term variations in air pollutants and weather parameters were also examined through a 20-day period before the confirmed PCR diagnostic of COVID-19. We found positive associations for diabetes and COVID-19 mortality (OR 2.2 CI 95%: 1.1, 4.4). Regarding environmental factors, we found no association between COVID-19 mortality and air pollutants and weather parameters; however, our study suffers from strong disparities—such as patient characteristics—between fairly polluted and less polluted cities. In order to overcome those disparities between cities, we aimed to explore the relationship between air pollution and COVID-19 mortality within each city, but even with the high-efficiency modelisation systems, differences in air pollutants were too small to estimate the effect of air pollution at the city level. Thus, this study highlights the need to improve the estimation of individual exposure to air pollution. To address this issue, solutions exist such as the increase of the number of fixed air monitors, or even better, through the use of individual markers of air pollution exposure such as urinary black carbon or passive individual samplers. Furthermore, we underline that outdoor air pollutant concentrations may not be representative of individual exposure, especially in the elderly, thus, we suggest that further studies focus on indoor air pollution. Regarding meteorological conditions, we found no association between UV, temperature, wind speed and COVID-19 mortality. We found a positive association between an increase in relative humidity (RH) and COVID-19 mortality, however, the influence of RH on COVID-19 mortality remains unclear, and additional studies are needed to confirm this potential link.

COVID-19 Mortality, Air Pollution, Particulate Matter, Ultraviolet Radiation, Temperature

Bourdrel, T. , Zabrocki, L. , Compte, N. , Bravenboer, B. , Decours, R. , Pelerin, H. , Decker, L. , de Kergaradec, L. , Lilamand, M. , Baudron, C. , Fougère, B. , Mahmoudi, R. , Schorr, B. , Kaltenbach, G. , Vogel, T. , Puech, V. , Blanc, F. and Bind, M. (2022) Individual and Environmental Risk Factors for COVID-19 Mortality in Elderly in 7 European University Hospitals. Journal of Environmental Protection, 13, 508-526. doi: 10.4236/jep.2022.137032.