Ground-level ozone as a potential risk factor for emergency hemodynamic conditions in residents of the southern coast of Crimea

INTRODUCTION. The World Health Organization (WHO) ranks ground-level ozone as the second most dangerous atmospheric pollutant to human health. Its concentration must be monitored when determining air quality. This is especially important in southern regions, where conditions favour its formation in elevated concentrations. While the link between ozone exposure and respiratory diseases is well established, the evidence regarding cardiovascular diseases is controversial. OBJECTIVE. To determine the role of ground-level ozone as a possible risk factor in the occurrence of emergency conditions of the hemodynamic system of residents in the territory of the Southern Coast of Crimea. MATERIALS AND METHODS. A study was conducted on the daily registration of emergency medical services (EMS) calls due to cardiovascular emergencies, based on data from the Unified Crimean Republican Territorial Center for Emergency Care of the Ministry of Health of the Republic of Crimea for the period 2018–2022, and ground-level ozone concentrations (GLO) based on data from the Karadag station of background environmental monitoring (SBEM). GLO measurements were performed optically using an APOA 370 automatic gas analyzer (HORIBA); the dependence of the compared data was analyzed using nonparametric Spearman correlation analysis. RESULTS. During the study period, the ozone depletion level on the Black Sea coast of Crimea exhibited typical daily and seasonal fluctuations, reaching maximum values in the summer months and daytime hours. However, atypical increases in ozone depletion were also observed during cold or cool seasons: for example, in January 2019 and December 2022. Average annual ozone concentrations generally exceeded the standard values. Positive significant correlations were observed between ozone depletion and the incidence of cardiovascular emergencies in February 2019, 2020, and 2022, March 2022, and April 2020. Negative correlations were found in September 2018 and 2022, May 2019, and January 2022. Moreover, if minimum ozone concentrations were at least 40 μg/m³ and rose to 100 μg/m³ during the month, their increase led to an increase in the number of emergency calls. If minimum ozone concentrations were within 15–20 μg/m³ and did not exceed 50–60 mg/m³ during the month, a negative relationship between the number of calls and ozone concentrations was observed, indicating a nonlinear nature. DISCUSSION. The data obtained establishing the significance of ozone for the functioning of the cardiovascular system in the coastal area of Crimea are consistent with a number of scientific publications, including those on the multidirectional nature of the identified relationship, which may indicate either a delayed response to increased ozone or its nonlinear nature. The indirect influence of other meteorological and anthropogenic factors may play a significant role in the final effect of ozone, which likely explains often the controversial nature of epidemiological data obtained in different regions of the world. CONCLUSION. Analysis of emergency medical service data on the dependence of the incidence of cardiovascular emergencies on the ozone level provides grounds for considering ground-level ozone as a risk factor for cardiac patients, but its ambiguous nature requires further research to determine its dangerous/safe levels in a region such as the Black Sea coast of Russia.

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