[Ammonia as inhalatory irritant]

Bronchopulmonary damage caused by heavy exposure to ammonia may result in chronic obstructive bronchitis, bronchial hyperresponsiveness, in rare cases also in a combined ventilation pattern. Exposure to ammonia for several years, as it occurs in swine confinements in pig-fattening farms is associated with a shift-related decrease of FEV1, FEF25-75 and PEF. Several studies show that ammonia at the TLV (20 ppm) inconstantly causes severe cough. In this connection, patients frequently cannot perform maximum forced ventilation manoeuvres. This leads to reduced spirometric values which usually do not represent bronchial obstruction. This interpretation is supported by normal values obtained by body plethysmography. Nevertheless, corresponding disorders may be associated with significant health impairment. Altogether, the results point predominantly to long-term effects. Obviously, continuous inflammation of the airways favours the development of chronic bronchitis. On this basis, susceptible subjects respond with airway symptoms, especially cough, upon re-exposure.