Acute cardio-respiratory effects of SO2 and NO2 exposure in southern Israel

Background: The impact of SO₂ and NO₂ on population health is growing, due to increasing industrialization. Objective: To measure the effects of ambient SO₂ and NO₂ on cardiac and respiratory emergency department (ED) patient load. Methods: Half-hourly values for NO₂ and SO₂ concentration, temperature, precipitation, and wind direction from 18 regional monitoring stations between January 2000 and December 2006, were pooled by consecutive 12-hour periods. Outcome data, based on ICD-9 codes, included acute cardiac and respiratory admissions to a regional ED. Cases and controls were periods with the highest and lowest ED patient volumes, respectively. For each 12-hour period, pollutant concentrations were introduced as independent exposure variables. Measurements during case and control periods were compared using logistic modeling to estimate the effects of pollutants on the risk of high-volume ED periods, adjusting for additional air quality parameters. Poisson regression addressed the number of daily admissions, enabling evaluation of the risks associated with single-unit increases in pollutant concentration. Results: Logistic regression analysis of the 2000-2004 data subset demonstrated that NO₂ and SO₂ concentrations were higher during case periods than during control periods: OR=1.45 (95%CI 1.09-1.93) for SO₂ and OR=2.34 (95%CI 1.69-3.23) for NO₂. The strongest specific association was found between NO₂ exposure and acute respiratory ED outcomes (OR=1.82, 95%CI 1.28-2.58). Poisson regression demonstrated similar associations, expressed as relative risks: RR=1.002 (95%CI 1.001-1.003) for NO₂ and RR=1.0065 (95%CI 1.0028-1.0102) for SO₂. Conclusion: Increased cardio-respiratory patient load associated with SO₂ and NO₂ concentrations is a marker of these pollutants' impact on population health.