Acute Respiratory Responses of Human Subjects to Air Quality in a Swine Building

Abstract

The purpose of this study was to test the following hypotheses: (1) an air quality control strategy can be directly evaluated by measuring respiratory responses of a human subject; and (2) improved air quality can improve human respiratory responses in swine building environments. Twenty human subjects, between 18 and 35 yr of age, who had never been exposed to an enclosed swine environment before, were exposed to air qualities in a treatment room and a control room, in a swine building. The treatment room was sprinkled with crude canola oil, which reduced the dust, endotoxin, ammonia and hydrogen sulphide by 93% (from 2·41 to 0·15 mg/m3), 89% (from 3984 to 452 EU/m3), 30% (from 26 to 18·3 p.p.m.) and 27% (from 0·38 to 0·27 p.p.m.), respectively, compared with the control room. The control room was identical to the treatment room but had no oil sprinkling treatment. Each subject spent 5 h in each room. They were scheduled to do a bicycle exercise that was intended to simulate the barn workers’ workload. Shift changes in forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and white blood count (WBC) of the subjects between the treatment and the control were all significantly different (p<0·03). Shift changes of FEV1were −1·94% for the treatment and −9·93% for the control. Shift changes of WBC were 6·35 count/μl for the treatment and 8·78 count/μl for the control. Means (±SE) of methacholine challenge (MC) were 181±108 and 140±113 mg/ml for the treatment and the control, respectively, but they were not significantly different (p=0·18) due to the large variation in values. This study demonstrated that (1) an air quality control strategy could be directly evaluated by measuring human respiratory responses; and (2) improved air quality (e.g. oil sprinkling) resulted in improved acute respiratory responses of human subjects.