Abstract
The health hazard of long-term living under non-protected, asbestos-containing corrugated roofing sheets (CRS) is still debatable. Although the fibres are bound in hard Portland cement mass (asbestos-cement composite), the weathering processes could develop a loose and brittle surface layer which might allow fiber loss with consequent air dispersion. The objective of the present study, therefore, was to measure indoor airborne concentration of asbestos fibres in low-income residences of large urban areas in Brazil which have been covered by unprotected CRS for at least 15 years. Secondarily, we aimed to perform these measurements in different outdoor environments in the same cities to obtain an index of the background asbestos exposure. All samples were analyzed according to the International Standard ISO 10312, 1995 using direct-transfer Transmission Electron Microscopy (TEM). Sampled residences have been roofed with unprotected CSR for a long period (> 20 yrs in 31/35 (88.5%)) and the level of deterioration was subjectively considered as moderate-to-advanced in (28/35 (80%). TEM analysis found only 1 chrysotile fiber ≥ 5 mm in 1 out of these 35 residences (0.00083 fb/ml). Analysis of the outdoor samples either in the neighborhood or in remote areas showed airborne fibre concentration levels similar to previously described in large urbanized cities around the world (0.00042 to 0.00084 fb/ml). These data indicate that indoor exposure to asbestos in residences which have long been covered by unprotected asbestos-cement CRS is similar to background exposure in urbanized areas.
Supported by: Supported by: CNPq/MCT, Brazil, FUNAPE (GO), Brazilian Crysotile Institute.
- © 2011 ERS
