“…The most common indoor sources are produced during combustion processes, operation of electric appliances, computer equipment, etc, (e.g. Abdullahi et al, 2013;Wu et al, 2012;Glytsos et al, 2010;Sjaastad and Svendsen, 2008;Lazaridis et al, 2006;Abt et al, 2000;Hetland et al, 2000). There are also many poorly understood emerging sources that introduce new exposure aspects indoors such as electronic cigarettes, decorative ethanol fireplaces, zeolites from washing powders, and household products containing nanoparticles (Schripp et al, 2014(Schripp et al, , 2013Quadros and Marr, 2011;Gudmundsson et al, 2007).…”