Effect of season and weather on pediatric emergency department use

Abstract

It is commonly believed that emergency department (ED) use is affected by extreme weather. To test this hypothesis, data concerning use of a pediatric ED during three seasonally diverse months was analyzed in the light of Weather Bureau information concerning daily conditions during the study months. Seven measures of extreme weather were defined: 1) extreme cold (daily high temperature ≤25°F); 2) extreme heat (daily high temperature ≥88°F); 3) unusual cold (winter) with departure from normal of mean temperature <−10°F; 4) unusual heat (summer) with departure from normal of mean temperature >10°F; 5) precipitation ≥0.25 inches (in water-equivalent inches); 6) stormy (thunderstorm, hail, ice, or blowing snow); 7) snow-covered (≥6 inches of snow on the ground). Seasonal use patterns were examined and the proportion of days with each weather factor was compared with the proportion of visits on days with the factor. The data indicate 1) season has a major affect on ED use because it affects prevalence of disease and injury; 2) extremely cold and stormy conditions significant reductions in ED use of approximately 5–20%; 3) 80–95% of expected visits are made on days with very bad weather. The data indicate that weather is a minor factor in determining ED use.