Air pollution mortality in elderly in Tehran, Iran

There are many studies discussing the correlation between air pollution and human health hazards. Yet, in Tehran there is not a survey using time series methodology. Thus, we conducted a study based on time series data on the topic in Tehran, Iran. Mean levels of NO, N02, NOX, CO, 03, S02  and PM 10 (particulate matters smaller than 10 micrometer in diameter) were measured in one station of Tehran's Air Quality Control Corporation and were used as main independent variables. Mean temperature, mean humidity, day of the week, month and season were considered as potential confounders and deaths in people older than 64 years in Tehran was the dependent variable. All the variables were measured during Mar. 1998 to Dec. 1999. Concentrations of air pollutants were different between seasons and so were the means of daily deaths. Out of main independent variables, S02, CO and PM l O showed statistically significant relations with the dependent variable (P<0.05). After controling for confounders, there was 3.4%, 2.6% and 3.36% increase in death rates, respectively, for each interquartile ascending (increase from 25th centile to 75th centile) in association to the mentioned pollutant centile concentration. No autocorrelation between residuals was observed (r=-0.059). The study showed that meteorological variables can confound the relation between air pollution and rate of deaths per day.