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Background: The increase in work-related respiratory complaints in artificially ventilated buildings have multiple causes, and intervention studies are a valuable approach to understanding possible mechanisms. Study objectives: To analyze the effects of an intervention in a ventilation system with >20 years of continuous use, and with a high rate of building-related respiratory complains. Design: An epidemiologie study was done among individuals working in places with ventilation machinery and duets with > 20 years of use, before and after intervention. Analysis of symptoms and logistic regression were performed to check the associations between air-conditioning intervention and reported symptoms. Results: The air-conditioning intervention showed a protective effect on building-related worsening of respiratory symptoms (odds ratio, 0.132; 95% confidence interval, 0.030 to 0.575), naso-ocular symptoms (odds ratio, 0.231; 95% confidence interval, 0.058 to 0.915), and persistent cough (odds ratio, 0.071; 95% confidence interval, 0.014 to 0.356). Conclusion: Intervention in high-risk occupational locations can be effective in improving perceived indoor air quality. Key words: air conditioning; air pollution; indoor; intervention studies; occupational health. [ABSTRACT FROM AUTHOR]

Background: The increase of work-related respiratory complaints in artificially ventilated buildings has multiple causes, and the role of allergen exposure and symptoms is still controversial., Study Objectives: To analyze the risk factors and the association of work-related symptoms with allergen exposure and different conditions of the same air conditioning system in São Paulo, Brazil., Design: Workers were classified according to characteristics of the air conditioning system: the first group (group 1) with ventilation machinery and ducts with > 20 years of use, the second group (group 2) with ventilation machinery with > 20 years of use and ventilation ducts with < 2 years of use, and the third group (group 3) with ventilation machinery and ducts with < 2 years of use. Logistic regression was performed to check the associations between air conditioning groups, allergen exposure (fungi, mites, animal dander, and cockroach), and symptoms., Results: There was a higher prevalence of building-related worsening of respiratory symptoms (p = 0.004; odds ratio [OR], 8.53) and symptoms of rhinoconjunctivitis (p = 0.01; OR, 8.49) in group 1. There was a lower relative humidity (p = 0.05) and nonsignificant lower temperature in group 1, when compared to the other groups. The viable mold spores totals were higher outdoors than in the indoor samples (n = 45, p = 0.017). There were higher levels of Der p 1 in group 2 (p = 0.032). All allergen levels were considered low., Conclusion: There was a strong association of building-related upper-airway symptoms with places having ventilation systems with > 20 years of use.