Urban enhancement of PM₁₀ bioaerosol tracers relative to background locations in the Midwestern United States

Abstract

Bioaerosols are well-known immune-active particles that exacerbate respiratory diseases. Human exposures to bioaerosols and their resultant health impacts depend on their ambient concentrations, seasonal and spatial variation, and co-pollutants, which are not yet widely characterized. In this study, chemical and biological tracers of bioaerosols were quantified in respirable particulate matter (PM10) collected at three urban and three background sites in the Midwestern United States across four seasons in 2012. Endotoxins from gram negative bacteria (and a few gram positive bacteria), water-soluble proteins, and tracers for fungal spores (fungal glucans, arabitol and mannitol) were ubiquitous and showed significant seasonal variation and dependence on temperature. Fungal spores were elevated in spring and peaked in summer, following the seasonal growing cycle, while endotoxins peaked in autumn during the row crop harvesting season. Paired comparisons of bioaerosols in urban and background sites revealed significant urban enhancements in PM10, fungal glucans, endotoxins and water-soluble proteins relative to background locations, such that urban populations have a greater outdoor exposure to bioaerosols. These bioaerosols contribute, in part, to the urban excesses in PM10. Higher bioaerosol mass fractions in urban areas relative to background sites indicate that urban areas serve as a source of bioaerosols. Similar urban enhancements in water-soluble calcium and its correlation with bioaerosol tracers point towards wind-blown soil as an important source of bioaerosols in urban areas.

Biomarkers as indicators of fungal biomass in the atmosphere of São Paulo, Brazil

“…These results demonstrate that these compounds alone do not contribute significantly to the PM10 or OC mass. However, these compounds can be indicators of the presence of other organics components of the same or similar sources, as also shown in others studies (Bauer et al, 2008a;Rathnayake et al 2016;Gosselin et al 2016).…”

“…Arabitol and mannitol concentrations observed in our study are similar to those found by Caumo et al (2016) for São Paulo in winter of 2012 and 2013, Gosselin et al (2016) in a semiarid montane environment and Burshtein et al (2011) in Israel (Table 1). However, higher concentrations were observed in numerous studies as presented in Table 1 (Bauer et al, 2008b;Graham et al, 2003;Urban et al, 2014;Zhang et al, 2010;Rathnayake et al, 2016;Zangrando et al, 2016;Gosselin et al, 2016 -rainy period). These locations are examples of sampling sites in urban and forest environments, rendering the differences in concentrations mostly due to the difference in land use characteristics and/or sampling period.…”

“…Most of these studies only mention the mannitol and arabitol fungal origin, while they focus otherwise on biomass burning (BB) or characterisation of the organic aerosol in the atmosphere in general (Caumo et al, 2016;Urban et al, 2014;Zangrando et al, 2016;Graham et al, 2003). Other studies (Table 1) considered arabitol and mannitol as important fungal biomarkers but do not estimate the fungal biomass in the atmosphere (Burshtein et al, 2011;Rathnayake et al, 2016;Liang et al, 2016). To the best of our knowledge, just a few studies worldwide have been performed using these carbohydrates, mannitol and arabitol, as biomarkers for estimating the fungal biomass in the atmosphere and their contribution to the PM10 mass, as presented in Table 2 2008a, Bauer et al;2008b;Zhang et al, 2010;Gosselin et al;2016), and none of such studies have been conducted in São Paulo.…”

Influence of rain on the abundance of bioaerosols in fine and coarse particles

“…Ambient bacterial levels increase with temperature (Carty et al, 2003) due to conditions that favor vegetation and bacterial habitat (DeLucca and Palmgren, 1986;Romantschuk, 1992). In vegetation-covered areas, atmospheric bacterial concentrations have been shown to increase during and after simulated rain events (Graham et al, 1977;Robertson and Alexander, 1994) as well as natural rain events (Constantinidou et al, 1990;Huffman et al, 2013). This response to precipitation has been attributed to rain moving plants and aerosolizing bacteria (Jones and Harrison, 2004).…”

On the interpretation of bioaerosol exposure measurements and impacts on health

“…These studies have focused mainly on characterizing and quantifying the microbial content in bioaerosols. Some of them focused solely on bacteria and/or fungi, others also examined endotoxins, (1→3)β-D-glucan, and PM 10 (Abbasi and Samaei 2018;Fang et al 2007;Fatahinia et al 2018;LeBouf, Yesse, and Rossner 2012;Lee and Jo 2006;Mota et al 2008;Rathnayake et al 2016). Very few studies have included the health effects of outdoor bioaerosol exposure in their studies (Karottki et al 2014).…”