Comparison of Responses and Deposition Following Human Exposures Via Oral or Nasal Inhalation of Sulphuric Acid Aerosols

Abstract

Controlled human exposure studies with inhaled air pollutants frequently utilize mouth breathing. To determine the extent that the route of inhalation influences airway resonses to particulate pollutants, we examined pulmonary responses of asthmatics breathing sulfuric acid (H₂SO₄)aerosols by oral or nasal inhalation. Asthmatics were exposed to H₂SO₄aerosols in a 45m³chamber for one hour including 10minutes of exercise or via a mouthpiece for 16 minutes during resting ventilation. We produced aerosols in concentrations of 100 μg/m³and 450 μg/m³. We measured before and immediately after all exposures FYC, FEV, and specific airway conductance (SGaw). At the 450 μg/m³ concentration, there were remarkable similarities in airway resonses desite the different exosure routes . Although the exposures were not strictly comarable in duration. we calculated tracheobronchial (TB) deposition for the two modes of aerosol administration and utilized con temorary models for deposition in explaining the lack of qualitative and quantitative distinctions in the pattern of response.