Retrospective analysis of the relationship between the frequency of medical emergency calls by patients with bronchial asthma and the concentration of ground-level ozone on the South Coast of Crimea

Background: Russian studies still underestimate one bronchial asthma risk factor, namely, the ground-level ozone recognized by the World Health Organization as the second most dangerous toxicant for the respiratory system. It is of particular importance to determine safe levels of ozone exposure, particularly in areas where patients are undergoing pulmonary rehabilitation and conditions are conducive to the formation of elevated ozone concentrations.

Aim: To identify and describe the relationship between the frequency of medical emergency calls by patients with bronchial asthma and the ground-level ozone concentration (GLOC) on the South Coast of Crimea.

Material and methods: The study utilized data from the medical emergency calls in Yalta by patients with bronchial asthma in 2010–2014. The GLOCs for the same period were measured at the Karadag Background Environmental Monitoring Station by optical method using APOA 370 (HORIBA) automatic gas analyzer. The correlation between the number of medical emergency calls and GLOC values was analyzed using Spearman’s correlation coefficient.

Results: The number of medical emergency calls increased from 2010 to 2014, rising from 471 to 661. During the same period, GLOCs exceeding the permissible average annual values were observed. Correlation analysis revealed that ground-level ozone was a significant factor affecting the condition of bronchial asthma patients over the 2010–2014 period, to varying degree. Five statistically significant ( p ≤0.05) and nine tendency-level ( p ≤0.10) correlations were identified between the frequencies of medical emergency calls and the daily average amplitudes of fluctuations and maximal and minimal GLOCs. The greatest number of significant correlations was reported in 2012, which was also a year marked by high amplitudes of GLOC fluctuations in the context of episodes of above-limit single ozone concentration and higher daily averages, similar to 2011. The correlations were positive, with the majority exhibiting a weak association (0.35 ≤Rs ≤0.48). These correlations were not observed during the warm seasons, when GLOC is typically higher, but during the cold season.

Conclusion: The established correlations, when considered alongside reliable international data on the negative effect of ozone on respiratory health, serve to highlight the importance of further research in the region. It is imperative to ascertain the safe GLOC levels, taking into account the concomitant meteorological and technogenic factors of the South Coast of Crimea, which have the potential to significantly modify the effect of ozone on the human body. This will facilitate the development of an early warning system to mitigate the adverse effects of ground-level ozone on asthmatic patients.