10/22/03 Low-level ozone exposure and childhood asthma symptomsSummaryPrevious studies have suggested that exposure to high levels of ozone and particulate matter of ú 2.5 micron diameter is a risk factor for respiratory symptoms in childhood asthma. In this current study, Gent et al of Yale Univ. School of Medicine in New Haven, CT prospectively examined parent-reported daily asthma symptoms and rescue med use in 271 children (< 12 years old) with physician diagnosed asthma. They found that increased levels of ozone, even within Environmental Protection Agency (EPA) approved levels, were associated with increased asthma symptoms in those children already on maintenance asthma medication. However, there was no association of such symptoms with ozone levels in those asthmatics not being treated with maintenance medications. There was no association of asthma symptoms with small diameter particulate matter levels within EPA acceptable levels. The authors concluded that even "acceptable" airborne levels of ozone can aggravate asthma in children with more pronounced disease. Reference JAMA 2003; 290:1859-67 Editor's Comments In my opinion, these "guilt by association" findings in epidemiologic studies do not definitely prove causality. However, they are certainly suggestive that even EPA-acceptable levels of ozone are potentially hazardous to children with active asthma. A previous study in Southern California indicated that asthma was worsened in children playing outdoor sports during time of increased outdoor levels of ozone. There was no significant association of asthma symptoms with outdoor levels of other air pollutants assessed in that study.
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