Association between ozone and hospitalization for acute respiratory diseases in children less than 2 years of age.

To clarify the health effects of ozone exposure in young children, the authors studied the association between air pollution and hospital admissions for acute respiratory problems in children less than 2 years of age during the 15-year period from 1980 to 1994 in Toronto, Canada. The daily time series of admissions was adjusted for the influences of day of the week, season, and weather. A 35% (95% confidence interval: 19%, 52%) increase in the daily hospitalization rate for respiratory problems was associated with a 5-day moving average of the daily 1-hour maximum ozone concentration of 45 parts per billion, the May-August average value. The ozone effect persisted after adjustment for other ambient air pollutants or weather variables. Ozone was not associated with hospital admissions during the September-April period. Ambient ozone levels in the summertime should be considered a risk factor for respiratory problems in children less than 2 years of age.

Air pollution, aeroallergens and cardiorespiratory emergency department visits in Saint John, Canada.

Existing studies of the association between air pollution, aeroallergens and emergency department (ED) visits have generally examined the effects of a few pollutants or aeroallergens on individual conditions such as asthma or chronic obstructive pulmonary disease. In this study, we considered a wide variety of respiratory and cardiac conditions and an extensive set of pollutants and aeroallergens, and utilized prospectively collected information on possible effect modifiers which would not normally be available from purely administrative data. The association between air pollution, aeroallergens and cardiorespiratory ED visits (n = 19,821) was examined for the period 1992 to 1996 using generalized additive models. ED visit, air pollution and aeroallergen time series were prefiltered using LOESS smoothers to minimize temporal confounding, and a parsimonious model was constructed to control for confounding by weather and day of week. Multipollutant and multi-aeroallergen models were constructed using stepwise procedures and sensitivity analyses were conducted by season, diagnosis, and selected individual characteristics or effect modifiers. In single-pollutant models, positive effects of all pollutants but NO2 and COH were observed on asthma visits, and positive effects on all respiratory diagnosis groups were observed for O3, SO2, PM10, PM2.5, and SO4(2-). Among cardiac conditions, only dysrhythmia visits were positively associated with all measures of particulate matter. In the final year-round multipollutant models, a 20.9% increase in cardiac ED visits was attributed to the combination of O3 (16.0%, 95% CI 2.8-30.9) and SO2 (4.9%, 95%CI 1.7-8.2) at the mean concentration of each pollutant. In the final multipollutant model for respiratory visits, O3 accounted for 3.9% of visits (95% CI 0.8-7.2), and SO2 for 3.7% (95% CI 1.5-6.0), whereas a weak, negative association was observed with NO2. In multi-aeroallergen models of warm season asthma ED visits, Ascomycetes, Alternaria and small round fungal spores accounted for 4.5% (95% CI 1.8-7.4), 4.7% (95% CI 1.0-8.6) and 3.0% (95% CI 0.8-5.1), respectively, of visits at their mean concentrations, and these effects were not sensitive to adjustment for air pollution effects. In conclusion, we observed a significant influence of the air pollution mix on cardiac and respiratory ED visits. Although in single-pollutant models, positive associations were noted between ED visits and some measures of particulate matter, in multipollutant models, pollutant gases, particularly ozone, exhibited more consistent effects. Aeroallergens were also significantly associated with warm season asthma ED visits.

Beyond administrative data: characterizing cardiorespiratory disease episodes among patients visiting the emergency department.

We attempted to address deficiencies in administrative health service data during a study of cardiorespiratory emergency department visits. From 1994-1996, we obtained data on 9,264 visits and conducted 1,772 follow-up interviews. The median interval between symptoms and visit ranged from 0.8 days (95% CI 0-1.7) for cardiac conditions to 4.0 days for chronic obstructive pulmonary disease (COPD) (95% CI 2.7-5.3) and respiratory infections (95% CI 3.5-4.5). Infection was the most common trigger of respiratory visits. Although most had improved at follow-up, symptoms persisted following the visit for a mean of 4.5 days (95% CI 3.8-5.4) for cardiac conditions to 8.4 days (95% CI 7.2-9.5) for COPD. Among adults aged < 70, the mean number of reduced activity days per episode ranged from 4.7 (95% CI 3.9-5.4) for asthma to 6.6 (95% CI 5.9-7.4) for respiratory infections. Our data assist in interpreting epidemiological studies based on administrative data, and illustrate the broad impacts of cardiorespiratory disease episodes.

Effects of particulate and gaseous air pollution on cardiorespiratory hospitalizations.

We obtained data on daily numbers of admissions to hospital in Toronto, Canada, from 1980 to 1994 for respiratory, cardiac, cerebral vascular, and peripheral vascular diseases. We then linked the data to daily measures of particulate mass less than 10 microns in aerodynamic diameter (PM10), particulate mass less than 2.5 microns in aerodynamic diameter (PM2.5), and particulate mass between 2.5 and 10 microns in aerodynamic diameter (PM10-2.5), ozone, carbon monoxide, nitrogen dioxide, and sulfur dioxide. Air pollution was only associated weakly with hospitalization for cerebral vascular and peripheral vascular diseases. We controlled for temporal trends and climatic factors, and we found that increases of 10 microg/m3 in PM10, PM2.5, and PM10-2.5 were associated with 1.9%, 3.3%, and 2.9% respective increase in respiratory and cardiac hospital admissions. We further controlled for gaseous pollutants, and the percentages were reduced to 0.50%, 0.75%, and 0.77%, respectively. Of the 7.72 excess daily hospital admissions in Toronto attributable to the atmospheric pollution mix, 11.8% resulted from PM2.5, 8.2% to PM10-2.5, 17% to carbon monoxide, 40.4% to nitrogen dioxide, 2.8% to sulfur dioxide, and 19.8% to ozone.