“…77 studies found which measured different pollutants indoor or/ and outdoors, where majority of these studies (59 studies) measured only outdoor pollutants (Abdul-Wahab et al, 1996, Al-Awadhi, 2016, Al-Awadhi, 2014, Al-Awadhi and Alshuaibi, 2013, Alet al, 2008a, Al-Dabbous and Kumar, 2014, Al-Dabbous and Kumar, 2015, Al-Dabbous et al, 2016, Aldaihani and Alenezi, 2017, Alenezi and Al-anezi, 2015, Al-Hurban and Al-Ostad, 2009, Alkandari and Moein, 2018, Alshammari, 2018, Al-Shammari, 2013, Bourasli, 2013, Bu-Olayan and Thomas, 2011, Bu-Olayan and Thomas, 2010b, Engelbrecht et al, 2009b, Kuśmierczyk-Michulec and Bourgouin, 2018, Li et al, 2020, Nasrallah et al, 2003, Yassin, 2011, Yassin et al, 2018a, Zaki et al, 2017.…”