The severity of the relationship between daily air pollution and cardiovascular deaths in Ahvaz, Iran- using generalized additive models (GAMs) for seven years during March 2008 - March 2015

Abstract Background and objectives: Some epidemiological evidence has shown the relationship between environmental air pollution and adverse health effects. The aim of this study was to evaluate the effect of daily air pollution on daily cardiovascular mortality in Ahvaz city. Materials and Methods: In this ecological study, air pollution data was inquired from the Ahvaz Environmental Protection Agency (EPA). The mortality data was collected from the Health Deputy of Ahvaz Jundishapur University of Medical Sciences. Using semi-parametric regression with Generalized additive models (GAM) was used to analyze the data with different lags of air pollutants for up to 7 days. An increase of 10 units in all pollutants except CO (1 unit) was used to compute the relative risk of deaths. Results: During March 2008 until March 2015, 10625 cardiovascular deaths occurred in Ahwaz, in which 6138 (57.8%) were male. The average number of daily, monthly, seasonal and annual deaths from cardiovascular diseases calculated 4.15, 126.49, 379.46, and 1517.86, respectively. Based on the analysis of the generalized additive model, the strongest correlation between NO2 and cardiovascular mortality was seen on lag 6, with a relative risk; RR = 1.007 and confidence interval; 95% CI: (1.002-1.012) for NO2. The correlation coefficient of NO2 with cardiac death was positive, significant and equal to 0.042 (P-value = 0.034). No significant relationship was found between the O3, SO2 and NO pollutants with the number of cardiovascular deaths. The increase in PM10 and CO levels had an inverse impact on the increase of cardiovascular mortality; and RR = 0.998, CI: (0.997-0.999) and RR = 0.989, CI: (0.979-0.999) for them, respectively. Conclusion: The results of this study showed that NO2 air pollutant is associated with increase cardiovascular mortality in Ahvaz. Reduction of environmental air pollution can be effective in reducing mortality from cardiovascular diseases and better life.