Effect of duration of exposure on airways of tannery workers depending upon histamine inhalation challenge

Background: Occupational asthma has a prevalence of about 9–15% in adult onset asthma.  Leather production in tanneries increases the atmospheric concentration of pollutants such as chromium, oxides of Nitrogen and Sulphur, particulate matter, volatile organic chemicals and Hydrogen disulphide, which may be linked to airway disorders. Methods: One-hundred-fifty male asymptomatic tannery workers of age 18 to 40 years were selected by convenient sampling and divided into three groups according to duration of exposure. The protocol of histamine inhalation challenge (HIC) has been standardized by American Academy of Allergy and Immunology. According to protocol HIC was not given to subjects with FEV1 less than 80%. Those who had decrease in FEV1 more than 20% before 8 µmol dose of HDP, were labelled as HIC positive and those who did not show any dip in FEV1 up to 8 µmol HDP, were labelled as HIC negative. Results: Group 1 with shortest exposure had lowest number of compromised airways and highest number of HIC negative subjects (p<0.01). Group 3 with longest exposure had highest number of compromised airways and lowest number of HIC negative subjects (p<0.01). Conclusion: Bronchial hyper-responsiveness with deranged PFT’s increases significantly with increase in duration of exposure (p<0.01). This study confirms the diagnostic value of HIC. Pak J Physiol 2019;15(3):3−5