STUDY OBJECTIVE: To explore the relation between incidence of sporadic and community acquired legionnaires" disease and exposure to potentially contaminated industrial aerosols. DESIGN: Geographical ecological approach using the postcode as the statistical unit. A multivariate Poisson regression model was used to model the relation between exposure to industrial aerosols and legionnaires" disease. SETTING: Metropolitan France. MAIN RESULTS: More than 1000 sources of industrial exposure (aerosol and plume of smoke) were identified in 42 French departments. After adjusting for confounding factors, there was a statistically increased incidence of legionnaires" disease in postcodes with plume of smoke in comparison with postcodes without (RR=1.45, 95% CI=1.12 to 1.87), and in postcodes with more than one aerosol in comparison with postcodes without (RR=1.37, 95% CI=1.04 to 1.79). CONCLUSION: These findings highlight that any industrial systems generating water aerosols should be regarded as potential sources of contamination for legionnaires" disease.