The hazardous effects of interior wall materials and surfaces on in¬door radon concentrations in Iranian houses

الملخص EN

Background : radon gas, which emanates from thorium and uranium ore-bearing rocks scattered throughout the surface soil and underground, can concentrate indoors and reach levels that represent a public health risk.

According to the World Health Organization (WHO) and the US Environmental Protection Agency (EPA), radon is the second leading cause of the lung cancer worldwide.

Due to the direct correlation between the lung cancer and radon exposure, it is important to directly, accurately, simply, and rapidly measure radon accumulation in Iranian dwellings built with various materials.

Thus, the aim of this study was to measure the effects of these materials on ambient radon concentrations in Iran dwellings.

Materials and Methods : we built a special chamber with interchangeable walls made with different materials and surfaces, including gypsum, wallpaper, oil paint, plastic paint, wall board, and Belk (a trademark for interior wall coating material composed of Cotton & Cellulose, mineral flakes, natural adhesive and Decorative additives).

Radioactive lantern mantles were used to elevate the radon (220Rn) levels in the chamber.

Chamber ventilation was designed to allow radon to accumulate, and active measurements were made with a prissy portable radon gas surveyor (Tabs Research Center, Shiraz University of Medical Sciences, Shiraz, IR Iran).

Data were analyzed using the Mann-Whitney U test with a significance criterion of P = 0.05 with the Bonferroni correction.

Results : the mean radon concentrations for wood and plastic paint were 869.0 ± 66.7 and 936.8 ± 60.6 Bq / m³, respectively while those for wallpaper and gypsum were 449.2 ± 101.7 and 590.9 ± 49.0 Bq / m³, respectively ; both significantly lower than other materials.

The mean radon concentrations for oil paint and Belk were 668.3 ± 42.3 and697.2 ± 136.7 Bq / m³, respectively.

Conclusions : individuals living in a house with interiors made of gypsum and covered with wallpaper receive an average annual radon dose smaller than people living in a house with interior wall coverings made of wall board or coated with plastic paint.

Wallpaper and gypsum are suggested as the safest interior wall construction materials.