Concentration and Community of Airborne Bacteria in Response to Cyclical Haze Events During the Fall and Midwinter in Beijing, China

Abstract

Since 2013, severe haze events frequently have occurred in Beijing between October and March, which have created a significant public health threat. Although variations in the chemical composition of these haze events have been studied widely, information pertaining to airborne bacteria in such haze events remains limited. In this study, we characterized the concentration, community structure, and composition of the airborne bacteria in response to nine haze events that occurred between October 1, 2015, and January 5, 2016. We also analyzed the correlations of airborne bacteria (concentration, community structure, and composition) with pollution levels and meteorological factors. The results indicated that airborne bacterial concentration showed a positive cyclical correlation with the haze events, but the bacterial concentration plateaued at the yellow pollution level. In addition, we found particulate matter (PM10) and relative humidity to be key factors that significantly affected the airborne bacterial concentration and community structure. Moreover, Halomonas and Shewanella were enriched on haze days for all nine of the haze events. Finally, the correlations between haze pollution and airborne bacteria in midwinter were weaker than those in fall and early winter, indicating an obvious staged distinction among the effects of haze on airborne bacteria. Our study illuminated the dynamic variation of bioaerosols corresponding to the cyclical haze events and revealed the interactions among air pollution, climate factors (mainly relative humidity), and airborne bacteria. These results imply that different strategies should be applied to deal with the potential threat of airborne bacteria during haze events in different seasons.

The global impact of bacterial processes on carbon mass

“…The cell concentrations C cell in the atmosphere homogenize aloft due to mixing processes and average to concentrations of ∼ 10 4 m −3 at most locations. However, spatial deviations might be present in particular locations, such as cell concentrations of ∼ 7 × 10 5 to 4 × 10 6 cells m −3 that were found during haze periods in China (Li et al, 2018;Xie et al, 2018) and even…”

“…Near the ground, typical concentrations of total airborne bacteria range from ∼ 10 2 to 10 6 cells m −3 , depending on the emission source (Burrows et al, 2009b) and on temporal, meteorological, or other environmental conditions influencing its propensity to emit particles to the air (Carotenuto et al, 2017;Huffman et al, 2013;Lighthart, 1997;Lighthart and Shaffer, 1995). Atmospheric mixing tends to homoge-B.…”

“…Additionally, the rapidly changing conditions in clouds, like condensationevaporation and freeze-thaw cycles, can cause strong physiological shocks and physical damage to cells, which can eventually be lethal. The viability of airborne microorganisms is thus very variable in space and time depending on environmental conditions (Fahlgren et al, 2010;Hu et al, 2017;Lighthart and Shaffer, 1995;Monteil et al, 2014), but yet the fact that a fraction of bacterial cells are viable was shown in many experiments of microbiological cultures from ambient aerosol samples (Amato et al, 2007b;Bovallius et al, 1978;Lighthart, 1997;Newman, 1948). This was specified and quantified more recently by direct observations and measurements of biological activity imprints (Amato et al, 2007aSattler et al, 2001;Wirgot et al, 2017).…”

Effect of probiotics on nasal and intestinal microbiota in people with high exposure to particulate matter ≤ 2.5 μm (PM2.5): a randomized, double-blind, placebo-controlled clinical study

“…High concentrations of environmental particles carry a large number of microorganisms, including many pathogens and opportunistic pathogens [17,18]. Particulate matter is one of the key factors affecting the airborne bacterial concentration and community structure [19,20]. Several studies demonstrated that high-levels of PM2.5/PM10 were related to alterations in the human pharyngeal [21], nasal [22], and intestinal [23] microbiota composition.…”

Characteristics of nasal and intestinal microbiota and effects of probiotics intervention in highly exposed people with PM2.5: a randomized, double-blind, placebo-controlled clinical study

“…High concentrations of environmental particles carry a large number of microorganisms, including many pathogens and opportunistic pathogens [10,11]. Particulate matter is one of the key factors affecting the airborne bacterial concentration and community structure [12,13]. Several studies demonstrated that high-levels of PM2.5/PM10 were related to alterations in the human pharyngeal [14], nasal [15], and intestinal [16] microbiota composition.…”