Estimating short-term mortality benefits associated with a reduction in tropospheric ozone. (1st May 2021) - Farzad, Kiarash
Abstract: Objective: Ground-level ozone (O3 ) is an air contaminant and can be harmful to the human health and environment. The objective of this study is to analyze the statistical trend of O3 and the association between the daily O3 exposure and mortality in Tehran, and to estimate the short-term health benefits of reducing the concentration of O3 in the ambient air of Tehran. Methods: The statistical parameters such as the mean, coefficient of variation, skewness, and kurtosis of O3 concentration for warm and cold seasons were calculated. The association and temporal relationship between the daily O3 concentration and different causes of mortality were analyzed using the generalized additive model (GAM). We utilized the BenMAP software to estimate the (short-term) avoidable mortality associated with reducing O3 concentration to the US EPA's standard level (70 ppb) for a full year and the warm seasons only. Results: The statistical analysis of O3 revealed an increase in the 1-h maximum and 8-h maximum concentrations in recent years. The association between O3 exposure and mortality was significant for the warm seasons when the concentration was highest. For every 10 ppb increase in the O3 concentration, there was 1.2% increase in mortality. Furthermore, the association was more significant for cardiovascular than respiratory attributed mortality. The analysis also showed a 3-day lag from the time of O3 exposure and mortality for the total population. The aforementioned scenario (for a full year) run in BenMAP resulted in 508 (90% CI: 69–937) annual all-cause avoidable deaths in Tehran. Conclusion: The maximum O3 concentration in Tehran has been increasing in the recent years, raising the alarm for potential adverse health impacts. In this study we found a significant association between short-term exposure to O3 and mortality during the warm seasons and a substantial predicted health benefit in reduction of this pollutant. Given the increasing ambient O3 concentration, it is necessary to further explore the aetiology/ies behind this increase and to consider how reductions in O3 precursors can reduce the public health burden in Tehran. Graphical abstract: Image 1 Highlights: The maximum concentration of O3 has risen over the last few years. O3 concentration is associated with mortality in warm seasons. 10 ppb increase in the O3 concentration, results in 1.2% increase in mortality. Reducing O3 to its standard limit could prevent 508 deaths annually.