owing to infant botulism. In another study, bioaerosols were collectedduring a dust storm in North Africa and the dust analysedusing bacterial 16S rRNA gene sequences [28]. Assessment using 16SrDNA clone libraries revealed the presence of various sporeformingbacteria over 3.3 μm in size and an even greater presenceof Actinobacteria and Bacteroidetes than 3.3-μm-sized aerosol particles.A large fraction of the bacteria were found in respirableparticles (<3.3 μm), which are associated with human pathogensrelated to several diseases. Thus, aerosolized bacteria in respirableparticles may have significant impacts on human health. Sigaudet al. treated mice with interferon γ (IFN-γ) aerosol followed by exposureto concentrated ambient particles (CAPs) from urban air, theninfected the mice with Streptococcus pneumoniae and evaluatedpulmonary innate immune response to the treatments [29]. Theirresults indicated that the combination of IFN-γ and CAPs exposureincreased pulmonary inflammation by recruiting morepolymorphonuclear granulocytes (PMN) to the lung and enhancingactivation of pro-inflammatory cytokine mRNAs. Therefore,combined IFN-γ and CAPs exposure lead to alveolar inflammationowing to oxidant stress, resulting in loss of antibacterial functionin PMN recruitment and pulmonary alveolar macrophages. Rintalaet al. concluded that the bacterial species typically found in indoordust are complex and mainly Gram-positive [30]. Tiny bacterial particlesfind excellent refuge inside buildings. There were rate changesof the phyla and species with seasonal variation. Studies have shownthat human exposure to bacterial particles is associated with humanmortality. Polymenakou et al. concluded that tiny particles act ascarriers of respirable bacteria [31]. Breathable bacteria from minutedust particles may pose a vital risk to human health. Whiteside et al.demonstrated significantly less endotoxin in paper bedding thanother types of bedding, with the highest endotoxin levels found incorncob and hardwood beddings [32]. The ranges of endotoxin concentrationwere 1913–4504 endotoxin units per gram (EU/g) incorncob bedding, 3121–5401 EU/g in hardwood bedding, 1586–2416 EU/g in corncob–paper mixed bedding, and less than5–105 EU/g in paper bedding. Coliform levels ranged from less than10–7591 colony forming units (cfu)/g in corncob beddings, 90 to4010 cfu/g in corncob–paper mixed beddings, from less than 10 to137 cfu/g in hardwood beddings, and less than 10 cfu/g in paperbeddings. Mean dust content was less than 0.15% in all bedding types
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