Background and Objective:
Synoptic circulation patterns (large-scale tropospheric motion systems) are likely to affect air pollution and morbidity associations, in light of increased global warming and changing climactic patterns. We evaluated the effect of synoptic circulation patterns (air masses) on the association of air pollution (PM10 and O3) and asthma/myocardial infarction (MI) hospital admissions among adults in North Carolina.
Daily surface meteorology data (including precipitation, wind speed, dew point) for five selected cities in North Carolina were obtained from the Climate Data Center of the National Oceanic Atmospheric and Oceanic Administration. We used a spatial synoptic classification (SCC) system (Sheridan, 2002) to classify each day over the ten year period with one of eight different climatic patterns (dry polar, moist tropical, etc.). Daily 24 hour ambient concentrations of PM10 and O3, were obtained from the U.S. EPA AQS (Air Quality System.) Asthma and MI hospital admissions data from a ten year period, 1996–2005, were obtained from the NC Department of Health and Human Services. Generalized linear models (GLMs) were used to assess the association of the hospitalizations with PM10 and O3 concentrations and specific air mass types with a zero to five day lag. We examined the effect across cities on days with same air mass type. In all models we adjusted for relative humidity, pressure, dew point, temperature, wind speed, and day-of-the-week effects.
Ozone was associated with asthma and MI admissions under dry moderate air conditions (23% increase [95% CI 17, 30] and 17% increase [95%CI 10, 19], respectively.) PM10 was associate with asthma hospitalizations (19% increase, 95%CI 6, 28], but not MI hospitalizations, under dry moderate conditions. A similar pattern was found for the moist tropical air mass.
Certain synoptic circulation patterns in conjunction with ambient air pollutant levels, were associated with increased asthma and MI hospitalizations.