Acute Symptom Responses to Environmental Tobacco Smoke in Asthmatic and Nonasthmatic Individuals

Abstract

Acute responses to 65 min exposures to environmental tobacco smoke (ETS) were tested in 24 healthy non-asthmatic nonsmokers and 16 asthmatic nonsmokers, using an environmental chamber. Each subject was exposed to air (sham), and machine-generated cigarette smoke containing 17 ppm and 31 ppm carbon monoxide (CO). Nonasthmatic subjects exercised intermittently (mean respiratory minute volume (VE) of 44 l/min during each of two 15–min exercise bouts); asthmatic subjects remained at rest. After completion of the exposure, subjects made a 0–5 rating of the severity of symptoms, as well as rating the overall severity of exposure on a 0–100 scale. Both symptoms and exposure severity rating were significantly related to CO concentrations. Ratings for a given ETS exposure tended to be higher for asthmatic than for nonasthmatic subjects. Overall exposure severity rating was significantly (p < 0.05) related to four symptom scores for the asthmatics and three for the nonasthmatic subjects. Symptoms common to both groups included unpleasant odour, and nasal discharge; shortness of breath was unique for nonasthmatics and eye irritation for asthmatk subjects. Although the nonasthmatic subjects were exercising intermittently, and thus received both a higher respiratory exposure (calculated from a CO-based index of ETS concentration, VE, and time) and biological exposure (calculated independently using a rebreathing estimate of the increment in carboxyhemoglobin level), the asthmatic subjects appeared to be more adversely affected by the ETS exposures in terms of their subjective responses.