Association between ambient air pollution and fatal stroke mortality in Songjiang District of Shanghai

Objective To investigate the risk of fatal stroke mortality associated with short-term exposure to air pollution， and to determine the susceptible population.

Methods In this study， daily stroke mortalities of adults between 2012 and 2014 in Songjiang District， Shanghai were collected. Time-stratified case-crossover approach was used to assess the association between daily concentrations of air pollutants and fatal stroke mortalities.

Results This study included 514 patients who died from acute strokes. The average concentrations during the study period were 77.45 μg·m^-3 for PM_2.5， 21.22 μg·m^-3 for SO₂， and 57.59 μg·m^-3 for NO₂. The fatal stroke mortality of adults under the age of 65 was found to be significantly associated with NO₂. At the time of a Lag of 2 d and 03 d， a significantly higher risk of fatal stroke mortality in relation to NO₂ exposure was observed， and the OR values of ischemic stroke mortality for people were 3.86 （1.53-9.75） and 5.83 （1.40-24.34） respectively. People over the age of 65 were more sensitive to increased PM_2.5 concentrations， at the time of a Lag of 03 d， fatal strokes increased by 28% when PM_2.5 levels increased. A significantly higher risk of fatal stroke mortality in relation to increase of NO₂ concentration was observed among people who were overweight or obese.

Conclusion A significantly higher risk of fatal stroke mortality is associated with the increase of PM_2.5 and NO₂. The results also suggest that the susceptible population should take additional precautions to avoid or reduce the risk of fatal strokes.