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

BACKGROUND: Ambient 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. METHODS: In this study, we collected size-segregated (PM(10-2.5), PM(2.5-0.2)) 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. RESULTS: Source-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. CONCLUSIONS: Even 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.

Actinobacteria in indoor environments: exposures and respiratory health effects.

Actinobacteria are a large group of Gram-positive bacteria common in the environment, especially in the soil. They are morphologically diverse and extremely versatile in their metabolic activities. They produce tens of thousands of secondary metabolites with different biological activities. Exposure to actinobacteria in indoor environments is probably continuous, since they are both common environmental bacteria and human normal flora. However, the occurrence of some species of spore-forming filamentous actinomycetes has been associated with abnormal and health-hazardous situations, such as moisture damage of the building. The measured concentrations of actinobacteria indoors are low. Higher concentrations have been reported during the remediation work of moisture damaged buildings and in agricultural environments. Exposure to high concentrations of actinobacteria can cause allergic alveolitis. Other respiratory disorders have been reported, too and although the measured concentrations are low, the indoor exposure is always a mixture of many different agents, which may have synergistic effects. In vitro and in vivo studies have shown that actinobacteria are very immunoactive and hence, potential causative agents for respiratory and other disorders.

Indoor air particles and bioaerosols before and after renovation of moisture-damaged buildings: the effect on biological activity and microbial flora.

Many building-related health problems coincide with moisture damage and mold growth within a building. Their elimination is assumed to improve indoor air quality. The aim of this study was to follow the success of remediation in two individual buildings by analyzing the microbial flora and immunotoxicological activity of filter samples. We compare results from samples collected from indoor air in the moisture-damaged buildings before and after renovation and results from matched reference buildings and outdoor air. The microbial characteristics of the samples were studied by analyzing ergosterol content and determining the composition of fungal flora with quantitative polymerase chain reaction (QPCR). In addition, the concentrations of particles were monitored with optical particle counter (OPC). The immunotoxicological activity of collected particle samples was tested by exposing mouse macrophages (RAW264.7) for 24 h to particle suspension extracted from the filters, and measuring the viability of the exposed cells (MTT-test) and production of inflammatory mediators (nitric oxide, IL-6 and TNF*) in cell culture medium by enzyme-linked immunoassay (ELISA). The results show that for Location 1 the renovation decreased the immunotoxicological activity of the particles collected from damaged building, whereas no difference was detected in the corresponding samples collected from the reference building. Interestingly, only slight differences were seen in the concentration of fungi. In the Location 2, a decrease was seen in the concentration of fungi after the renovation, whereas no effect on the immunotoxicological responses was detected. In this case, the immunotoxicological responses to the indoor air samples were almost identical to those caused by the samples from outdoor air. This indicates that the effects of remediation on the indoor air quality may not necessarily be readily measurable either with microbial or toxicological parameters. This may be associated with different spectrum of harmful agents in different mold and moisture-damaged buildings.