Associations between air pollutants and emergency ambulance dispatches for all-cause and nervous system disease in China Qingdao: a time-stratified case-crossover study

Abstract

The health hazards of air pollution have been recognized worldwide, and emergency ambulance dispatches (EADs) data have excellent research value in the field of environmental health and wellness. This study evaluated EADs data from January 1, 2016 to December 31, 2019, in Qingdao to assess the impact of air pollution on all-cause as well as nervous system emergency ambulance dispatches (NS-EADs). This study adopted a time-stratified case-crossover design to construct a time-series distribution-lagged single-pollutant model to assess the effects of air pollution on all-cause and NS-EADs, stratified by gender, age, and season. Confounding factors that could affect the results were controlled for in the model. Air pollutants were positively associated with all-cause and NS-EADs. The findings of the single-day lag effect demonstrated positive associations between PM_2.5 (lag0 and lag1 days), CO (lag0 and lag1 days), PM₁₀ (lag0 and lag1 days), SO₂ (lag1 days), and NO₂ (lag1 days) with an increased risk of all-cause EADs. Additionally, O₃ (lag0 days), CO (lag0 days), PM₁₀ (lag0 days), and NO₂ (lag0 days) exhibited positive correlations with an elevated risk of NS-EADs. To be specific, with every 10 μg/m³ increase in the concentrations of O₃, CO, PM₁₀, and NO₂ at lag 0, there was a corresponding increase in NS-EADs risk of 0.67% (95% confidence interval, 0.05%, 1.30%); 0.05% (0.01%, 0.10%); 0.50% (0.13%, 0.87%); and 1.52% (0.24%, 2.82%), respectively. Stratified analysis revealed a higher risk of NS-EADs associated with air pollution, specifically observed in subgroups including individuals under 65 years old, males, and during the cold season. Air pollution was associated with all-cause EADs and NS-EADs, and males, people under 65 years old were more vulnerable to air pollution. Furthermore, the impact of air pollution is more pronounced during the cold season.