Role of microbial and chemical composition in toxicological properties of indoor and outdoor air particulate matter

Abstract

BackgroundAmbient air particulate matter (PM) is increasingly considered to be a causal factor evoking severe adverse health effects. People spend the majority of their time indoors, which should be taken into account especially in future risk assessments, when the role of outdoor air particles transported into indoor air is considered. Therefore, there is an urgent need for characterization of possible sources seasonally for harmful health outcomes both indoors and outdoors.MethodsIn this study, we collected size-segregated (PM10–2.5, PM2.5–0.2) particulate samples with a high volume cascade impactor (HVCI) simultaneously both indoors and outdoors of a new single family detached house at four different seasons. The chemical composition of the samples was analyzed as was the presence of microbes. Mouse macrophages were exposed to PM samples for 24 hours. Thereafter, the levels of the proinflammatory cytokines, NO-production, cytotoxicity and changes in the cell cycle were investigated. The putative sources of the most toxic groups of constituents were resolved by using the principal component analysis (PCA) and pairwise dependencies of the variables were detected with Spearman correlation.ResultsSource-related toxicological responses clearly varied according to season. The role of outdoor sources in indoor air quality was significant only in the warm seasons and the significance of outdoor microbes was also larger in the indoor air. During wintertime, the role of indoor sources of the particles was more significant, as was also the case for microbes. With respect to the outdoor sources, soil-derived particles during a road dust episode and local wood combustion in wintertime were the most important factors inducing toxicological responses.ConclusionsEven though there were clear seasonal differences in the abilities of indoor and outdoor air to induce inflammatory and cytotoxic responses, there were relatively small differences in the chemical composition of the particles responsible of those effects. Outdoor sources have only a limited effect on indoor air quality in a newly built house with a modern ventilation system at least in a low air pollution environment. The most important sources for adverse health related toxicological effects were related to soil-derived constituents, local combustion emissions and microbes.Electronic supplementary materialThe online version of this article (doi:10.1186/s12989-014-0060-6) contains supplementary material, which is available to authorized users.

The effects of indoor and outdoor dust exposure on the growth, sensitivity to oxidative-stress, and biofilm production of three opportunistic bacterial pathogens

“…Recently, studies have begun to focus on how these dust exposures can impact human health (Happo et al, 2008(Happo et al, , 2014Hogervorst et al, 2007;Jalava et al, 2009). These studies have indicated that certain toxic compounds, both indoors and outdoors, have steadily been accumulating over time (Garrison et al, 2014;Ravindra et al, 2004).…”

“…Outdoor contaminants (including microbes) typically affected indoor air quality most during the summer months and less during the winter time. Conversely, both indoor contaminants as well as microbes emanated from indoor sources during the winter months (Happo et al, 2014).…”

Chemical and microbial components of urban air PM cause seasonal variation of toxicological activity

“…In a very recent study conducted in a small Finnish town, Kuopio, the particulate sources, compositions and the induced toxicological responses showed considerable seasonal variations (Happo et al, 2014). From the particle sources, engine emissions and other combustion sources have been associated with mortality (Clancy et al, 2002;Hoek et al, 2002), exacerbations of heart disease (Lanki et al, 2006) and increased cardiovascular emergency room visits (Metzger et al, 2004).…”

‘Every breath we take: the lifelong impact of air pollution’ – a call for action

“…Particulate matter indoors may contain a different range of chemicals from that encountered outside, 25 including those from air fresheners 26 and microbial products. 27 In addition, polyaromatic hydrocarbons are emitted in large amounts during cooking and frying, 28 all made worse by the sealing of buildings for energy conservation. Indoor air is enriched in biological pollutants such as allergens from dust mites, pets and fungi, as well as microorganisms that become concentrated especially in damp conditions.…”