Modest Increases in Ambient Ozone Concentration are Associated with Increases in School Absenteeism

Frank D. Gilliland and John Peters
University of Southern California, Los Angeles
P30ES07048

Background: Poor air quality is widely recognized as a risk factor for causing or exacerbating pulmonary diseases such as asthma. Ozone (O3), nitrogen dioxide (NO2), and particulate matter less than 10 mm in diameter (PM10) are known to contribute to temporary changes in lung function, increase risk of respiratory infections, more visits to physicians and emergency rooms, increased hospital admissions, and increased mortality. The economic impact of these illnesses is staggering when medical expenses and lost work productivity are taken together. School absenteeism is an important but poorly understood adverse outcome in children causing missed learning opportunities and the inability of the children to fully participate in school activities. The National Asthma Education and Prevention Program, the President's Task Force on Environmental Health Risks and Safety Risks to Children, and the DHHS Asthma Workgroup have all targeted school absenteeism as a high priority in the fight against asthma.

Advance: This paper describes an investigation of the relationships between O3, NO2, PM10, and school absenteeismduring the first 6 months of 1996 in a cohort of 4th grade children living in 12 southern California communities. The pollutants were measured hourly at monitoring sites in each of the 12 communities. Short-term change in O3 was associated with substantial increases in school absences from both upper and lower respiratory illnesses. An increase of 20 ppb of daytime O3 was associated with increases of 62.9% in illness-related absentee rates, 82.9% for respiratory illnesses, 45.1% for upper respiratory illnesses, and 173.9% for lower respiratory illnesses with cough. In addition, the short-term effects of the O3 increase were larger in communities with lower average PM10 concentrations than communities with high average PM10.

Implication: This study demonstrates that relatively small changes in O3 are associated with increases in respiratory illnesses and subsequent school absenteeism in 9-10 year old children. The level of exposures observed in this study are common suggesting that the increases in school absenteeism resulting from relatively modest changes in ambient O3 concentration documents an important adverse impact on children's health and well-being.

Publication: Gilliland FD, Berhane K, Rappaport EB, Thomas DC, Avol E, Gauderman WJ, London SJ, Margolis HG, McConnell R, Islam KT, and Peters JM. The Effects of Ambient Air Pollution of School Absenteeism due to Respiratory Illnesses. Epidemiology, 2001 Jan;12(1):43-54.