“…However, such studies face significant challenges due to the broad diversity and tremendous variability in populations of airborne bacteria owing to different sources of origin, seasonal effects, local climate differences, weather patterns, local human activities, and local wind currents (Shaffer and Lighthart, 1997). In the past decades, many studies on the composition and distribution of airborne bacteria emerged around the world (Bovallius et al, 1978;Mancinelli and Shulls, 1978;Jones and Cookson, 1983;Lighthart and Kin, 1989;Lighthart and Shaffer, 1995;Lighthart, 1997;Seino et al, 2005;Abdel Hameed, et al, 2009;Houdt et al, 2009;Lee et al, 2010;Wang et al, 2010;Yassin and Almouqatea, 2010;Nasir et al, 2012). These investigations significantly enriched our baseline knowledge of the normal abundance, distribution and composition of bacteria in the atmosphere, and which has supported many applications related to public health and international security.…”