Pulmonary function changes in asthmatics associated with low-level SO2 and NO2 air pollution, weather, and medicine intake. An 8-month prospective study analyzed by neural networks.

This paper presents the response in subjects with asthma to gaseous air-pollution levels, weather, and medicine intake as identified by principal-component analysis and neural network techniques. Pulmonary function measured by respiratory peak-flow rate in nonallergic asthmatics was associated with ambient, low-level, air-pollution concentrations of sulfur dioxide and nitrogen dioxide, temperature, relative humidity, and medicine intake. Results from 27 nonallergic asthmatics aged 18-60 years with well-characterized bronchial asthma and regular medical treatment were analyzed from two cities. During an 8-month period, each subject kept a diary table, which included symptoms, lung function (evening peak flow), medicine intake, and tobacco smoking. High intake of medicine and high ambient temperatures corresponded to decreased peak flow. The changes in temperature did not occur in situations with low medicine intake. During frost periods, peak-flow values decreased independently of medicine intake and levels of SO2. During other times, increased levels of SO2 and NO2 increased temperature, and increased intake of medicine, and low relative humidity corresponded to decreased peak flow. Increased levels of SO2 and NO2 corresponded synergistically to decreased peak flow at levels above 40 micrograms/m3.