title: Nanomaterial containing wall paints can increase radon concentration in houses located in radon prone areas.
abstract: BACKGROUND
  Nowadays, extensive technological advancements have made it possible to use nanopaints which show exciting properties. In IR Iran excessive radon levels (up to 3700 Bq m-3) have been reported in homes located in radon prone areas. Over the past decades, concerns have been raised about the risk posed by residential radon exposure.
  
  
  OBJECTIVE
  This study aims at investigating the effect of using nanomaterial containing wall paints on radon concentration in homes.
  
  
  METHODS
  Two wooden model houses were used in this study. Soil samples from Ramsar high background radiation areas were used for simulating the situation of a typical house in radon-prone areas. Conventional water-soluble wall paint was used for painting the walls of the 1st house model; while the 2nd house model was painted with the same wall paint with montmorillonitenanoclay.
  
  
  RESULTS
  Three days after sealing the house models, radon level was measured by using a portable radon survey meter. The mean radon level inside the 1st house model (conventional paint) was 515.3 ± 17.8 Bq/m(3) while the mean radon concentration in the 2nd house model (nano-painted house model) was 570.8 ± 18.5 Bq/m(3). The difference between these means was statistically significant (P<0.001).
  
  
  CONCLUSIONS
  To the best of our knowledge, this study is the first investigation on the effect of nano-material containing wall paints on indoor radon concentrations.  It can be concluded that nano-material-containing wall paints should not be used in houses with wooden walls located in radon prone areas. Although the mechanism of this effect is not clearly known, decreased porosity in nano-paints might be a key factor in increasing the radon concentration in homes.
authors.affiliation: Department of Medical Physics and Medical Engineering, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: M
authors.initials: M
authors.lastname: Haghani
authors.affiliation: The Center for Radiological Research, Shiraz University of Medical Sciences, Shiraz, Iran ; Department of Medical Physics and Medical Engineering, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: S M J
authors.initials: SM
authors.lastname: Mortazavi
authors.affiliation: Radiation Research Center, Mechanical Engineering School, Shiraz University, Shiraz, Iran.
authors.forename: R
authors.initials: R
authors.lastname: Faghihi
authors.affiliation: Radiation Research Center, Mechanical Engineering School, Shiraz University, Shiraz, Iran.
authors.forename: S
authors.initials: S
authors.lastname: Mehdizadeh
authors.affiliation: Ph.D student of nanomaterials, Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran.
authors.forename: J
authors.initials: J
authors.lastname: Moradgholi
authors.affiliation: Master Student, Student Research Committee, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: L
authors.initials: L
authors.lastname: Darvish
authors.affiliation: Master Student, Student Research Committee, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: E
authors.initials: E
authors.lastname: Fathi-Pour
authors.affiliation: Master Student, Student Research Committee, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: L
authors.initials: L
authors.lastname: Ansari
authors.affiliation: Radiation Research Center, Mechanical Engineering School, Shiraz University, Shiraz, Iran.
authors.forename: M R
authors.initials: MR
authors.lastname: Ghanbar-Pour
keywords: Nano-montmorillonite; Nanoclay; Paint; Radon; Radon Prone Areas; Wall Covering