Ambient air pollution and daily pediatric hospitalizations for asthma.

GOAL, SCOPE AND BACKGROUND: A series of severe air pollution episodes in Europe and North America prior to 1960 have focused scientific and regulatory attention on the adverse effects of air pollution on human health. As a consequence of significant reductions in ambient air pollution levels in the intervening years, scientists and public health officials have become more concerned with the potential health effects of exposure to routine concentrations of air pollution. Several recent time series studies conducted worldwide have found relatively low levels of air pollutants that are below national standards were associated with adverse effects on mortality and morbidity. This study examined the effects of ambient air pollution indicators on the daily rate of pediatric hospital admissions for asthma in the Oklahoma City Metropolitan area from 2001-2003.

METHODS

Data were collected for the number of children < or = 14 years old hospitalized for asthma on a daily basis (N = 1270) and ambient concentrations of NO2, O3, PM2.5, mold and pollen concentrations, and meso-scale meteorological conditions. Results. Negative binomial regression analysis revealed significant relationships between the total number of hospitalizations per day and the one-hour maximum NO2 level, the proportion of susceptible children < 5 years old, and the ratio of temperature to humidity.

DISCUSSION

This study of the total number of children aged < or = 14 years old experiencing hospitalizations on a daily basis in the Oklahoma City area from 2001-2003 underscores factors other than ambient air pollution, especially when concentrations are low, affect hospitalizations for pediatric asthma. For example, information related to indoor air quality, health care, family history, and exposure to environmental tobacco smoke and other irritants are not obtainable. Yet, those factors are risk drivers for asthma. Similarly, health privacy requirements prevented obtaining data on physiological factors specific to each child such as differentials in airways functional capacity or other impairments influenced asthma exacerbation. This makes calculating relative risk inappropriate.

CONCLUSIONS

Although ambient air pollution concentrations and meteorological conditions influence pediatric asthma hospitalizations, they are not the major predictors in the Oklahoma City metropolitan area. This is consistent with other research that finds limited effects associated with low levels for concentrations of the criteria pollutants.

RECOMMENDATIONS AND PERSPECTIVES

Although limiting concentrations for criteria air pollutants to levels below human health-based standards exhibited beneficial effects, other factors also need to be identified and addressed in order to reduce pediatric hospitalizations for asthma.