Objective The aim of the study was to determine the prevalence and risk factors for allergic respiratory disease in spice mill workers.

Methods A cross-sectional study of 150 workers used European Community Respiratory Health Survey questionnaires, Phadiatop, serum specific IgE (garlic, chili pepper), spirometry and fractional exhaled nitric oxide (FeNO). Personal air samples (n=62) collected from eight-hour shifts were analysed for inhalable particulate mass. Novel immunological assays quantified airborne garlic and chili pepper allergen concentrations.

Results Mean dust particulate mass (geometric mean (GM)=2.06 mg/m³), chili pepper (GM=0.44 µg/m³) and garlic allergen (GM=0.24 µg/m³) were highest in blending and were highly correlated. Workers’ mean age was 33 years, 71% were men, 46% current smokers and 45% atopic. Spice-dust-related asthma-like symptoms (17%) were common, as was garlic sensitisation (19%), with 13% being monosensitised and 6% cosensitised to chili pepper. Airflow reversibility and FeNO>50 ppb was present in 4% and 8% of workers respectively. Spice-dust-related ocular-nasal (OR 2.40, CI 1.09 to 5.27) and asthma-like (OR 4.15, CI 1.09 to 15.72) symptoms were strongly associated with airborne garlic in the highly exposed (>0.235 µg/m³) workers. Workers monosensitised to garlic were more likely to be exposed to higher airborne chili pepper (>0.92 µg/m³) (OR 11.52, CI 1.17 to 113.11) than garlic allergens (OR 5.08, CI 1.17 to 22.08) in this mill. Probable asthma was also more strongly associated with chili pepper than with garlic sensitisation.

Conclusions Exposure to inhalable spice dust (GM >2.06 mg/m³) containing garlic (GM>0.24 µg/m³) and chili pepper (GM >0.44 µg/m³) allergens increase the risk of allergic respiratory disease and asthma.