" Chemical Characterization and Source Apportionment of PM2.5 in Rabigh, Saudi Arabia " Nayebare, Shedrack R; Aburizaiza, Omar S; Khwaja, Haider A; Siddique, Azhar; Hussain, Mirza M; Zeb, Jahan; Khatib, Fida; Carpenter, David O; Blake, Donald R