Pulmonary function changes in asthmatics associated with low-level SO sub(2) and NO sub(2) 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. 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 SO sub(2). During other times, increased levels of SO sub(2) and NO sub(2) increased temperature, and increased intake of medicine, and low relative humidity corresponded to decreased peak flow. Increased levels of SO sub(2) and NO sub(2) corresponded synergistically to decreased peak flow at levels above 40 mu g/m super(3).