Acute respiratory health effects of air pollution on children with asthma in US inner cities.

BACKGROUND: Children with asthma in inner-city communities may be particularly vulnerable to adverse effects of air pollution because of their airways disease and exposure to relatively high levels of motor vehicle emissions. OBJECTIVE: To investigate the association between fluctuations in outdoor air pollution and asthma morbidity among inner-city children with asthma. METHODS: We analyzed data from 861 children with persistent asthma in 7 US urban communities who performed 2-week periods of twice-daily pulmonary function testing every 6 months for 2 years. Asthma symptom data were collected every 2 months. Daily pollution measurements were obtained from the Aerometric Information Retrieval System. The relationship of lung function and symptoms to fluctuations in pollutant concentrations was examined by using mixed models. RESULTS: Almost all pollutant concentrations measured were below the National Ambient Air Quality Standards. In single-pollutant models, higher 5-day average concentrations of NO2, sulfur dioxide, and particles smaller than 2.5 microm were associated with significantly lower pulmonary function. Higher pollutant levels were independently associated with reduced lung function in a 3-pollutant model. Higher concentrations of NO2 and particles smaller than 2.5 microm were associated with asthma-related missed school days, and higher NO2 concentrations were associated with asthma symptoms. CONCLUSION: Among inner-city children with asthma, short-term increases in air pollutant concentrations below the National Ambient Air Quality Standards were associated with adverse respiratory health effects. The associations with NO2 suggest that motor vehicle emissions may be causing excess morbidity in this population.

Classification of asthma severity in children: the contribution of pulmonary function testing.

BACKGROUND: Despite increasing awareness of the National Asthma Education and Prevention Program guidelines, the relative contribution of symptom frequency or pulmonary function to the recommended asthma severity levels remains poorly understood. OBJECTIVE: To determine whether adding lung function measurements to clinical history substantially changes the asthma severity classification, thereby influencing treatment decisions. DESIGN: Baseline data were studied from children enrolled in 2 multicenter studies: phase 1 of the National Cooperative Inner-City Asthma Study (1992-1994) (cohort 1) and the Inner-City Asthma Study (1998-2001) (cohort 2). SETTING: Fifteen (8 for cohort 1 and 7 for cohort 2) major metropolitan inner-city areas in the United States. PARTICIPANTS: Inner-city children aged 8 through 11 years with asthma. MAIN OUTCOME MEASURES: Proportion of children reclassified from less severe asthma categories based on symptom frequency into more severe categories because of lung function. RESULTS: Of children with symptoms of mild intermittent asthma, 22.8% in cohort 1 and 27.7% in cohort 2 would be reclassified as having either moderate or severe persistent asthma. Of children with symptoms of mild persistent asthma, 31.2% in cohort 1 and 33.3% in cohort 2 would be similarly reclassified. CONCLUSIONS: In 2 different studies of inner-city children with asthma, approximately one third of the participants were reclassified into higher National Asthma Education and Prevention Program asthma severity categories when pulmonary function was considered in addition to symptom frequency. This may have direct implications for the undertreatment of asthma.