Effects of sulfuric acid aerosol on cardiopulmonary function of dogs, sheep, and humans.

Submicronic aerosol of sulfuric acid (H2SO4) originates from the burning of fossil fuels and discharge of vapor from the automobile engine equipped with the catalytic converter. This study was conducted to determine whether brief exposure to this aerosol in high concentrations adversely affects the cardiopulmonary system. In all studies, submicronic aerosol of sodium chloride was used as a control. Anesthetized dogs that breathed H2SO4 aerosol in concentrations up to 8 mg per m3 showed no effects on respiratory resistance, static lung compliance, and functional residual capacity. A 4-hour exposure to H2SO4 aerosol (4 mg per m3) produced no significant changes in mechanics of breathing, functional residual capacity, pulmonary and systemic arterial blood pressures, cardiac output, heart rate, and arterial blood gas tensions. Conscious sheep that breathed H2SO4 aerosol in concentrations up to 14 mg per m3 for 20 min had no alteration of tracheal mucous velocity in an immediate 3-hour follow-up period or 5 to 10 days later. Conscious sheep that breathed H2SO4 aerosol (4 mg per m3) for 4 hours had no significant alteration of tracheal mucous velocity immediately and 2 hours thereafter. Both normal and asthmatic adults breathing H2SO4 aerosol in concentrations up to 1 mg per m3 for 10 min showed no significant alteration of lung volumes, distribution of ventilation, ear oximetry, dynamic mechanics of breathing, oscillation mechanics of the chest-lung system, pulmonary capillary blood flow, diffusing capacity, O2 consumption, and pulmonary tissue volume. No delayed effects in pulmonary function nor exacerbation of bronchial asthma were observe during a follow-up period of a few weeks. The present study indicates that single exposure to submicronic H2SO4 aerosol does not produce an immediate or a delayed adverse effect on cardiopulmonary function in anesthetized dogs, conscious sheep, and normal and asthmatic adults.