Effects of sodium nitrate aerosol on cardiopulmonary function of dogs, sheep, and man

Submicronic aerosols of nitrate salts are synthesized in the atmosphere through further oxidation of nitrogen oxides produced during the burning of fossil fuels. This study was conducted to determine whether brief exposure to submicronic aerosol of sodium nitrate in high concentrations adversely affects the cardiopulmonary system. In all studies, submicronic aerosol of sodium chloride was used as a control. Anesthetized dogs breathing up to 10 mg/m³ of sodium nitrate (NaNO₃) aerosol for 7.5 min showed no significant alterations in respiratory resistance, static lung compliance, and functional residual capacity. A 4-hr exposure to NaNO₃ aerosol (5 mg/m³) produced neither significant changes in lung mechanics, functional residual capacity, pulmonary and systemic arterial pressures, cardiac output, heart rate, and arterial blood gases in anesthetized dogs nor a change in tracheal mucous velocity in conscious sheep. Both normal and asthmatic adults who breathed submicronic aerosol of NaNO₃ (up to 1 mg/m³) for 10 min showed no significant changes in lung volumes, distribution of ventilation, ear oximetry, dynamic mechanics of breathing, and oscillation mechanics of the chest-lung system. NaNO₃ aerosol (1000 μg/m³ for 10 min did not significantly change pulmonary capillary blood flow, diffusing capacity, oxygen consumption, and pulmonary tissue volume as measured by a rebreathing technique. Thus, brief exposure to high concentrations of submicronic aerosol of sodium nitrate does not produce immediate adverse effects on cardiopulmonary function of anesthetized dogs, conscious sheep, and normal and asthmatic adults.