There is a recent review paper that may be of interest: Pediatric Asthma and the Indoor Microbial Environment | SpringerLink
The global increase in the prevalence of asthma has been related to several risk factors; many of them linked to the “westernization” process and the characteristics of the indoor microbial environment during early life may play an important role. Living in moisture damaged homes contributes to the exacerbation and development of asthma. However, living in homes with a rich variety and high levels of microbes (e.g., traditional farming environments) may confer protection. While the results of previous research are rather consistent when it comes to observation/report of indoor moisture damage or when comparing farming versus non-farming homes, when actual measures targeting indoor microbial exposure are included, the picture becomes less clear and the associations appear inconsistent. This may partly be due to limitations of sampling and measurement techniques that make comparisons difficult and provide an incomplete picture of the indoor microbial environment and in particular also human exposure. In this regard, new generation sequencing techniques represent a potential revolution in better understanding the impact of the indoor microbiome on human health.
It is by Lidia Casas, Christina Tischer, and Martin TÃ¤ubel it was published in Current Environmental Health Reports as part of this collection: Topical Collection on Early Life Environmental Health
They discuss many issues of direct relevance to the microbiology of the built environment community and provide a good review of findings that have suggested connections between microbes from the indoor environment and asthma. They also provide a good overview of the different ways of assaying microbes and their components. Definitely worth a look.
Below are there conclusions, but the whole paper is worth a look
The existing evidence clearly points to negative effects of moisture damage or dampness and positive effects of farming living environments on the development of pediatric asthma. Microbial exposures linking to these environmental conditions are believed to contribute to the observed health impacts. However, when actual measures of the indoor microbial environment are considered, the results become inconclusive. This may partly be due to incoherence of sampling and measurement techniques used to date in epidemiological studies that make comparisons across studies difficult. More importantly, the use of specific sampling and measurement techniques show an incomplete picture of the indoor microbial environment and of actual quantity and quality of human exposure. Different sampling locations and methods may reflect different types of exposures. Also, since the development of the immune system must be seen from a longitudinal perspective, the time of sampling (i.e., early life or childhood) is crucial when interpreting health effects of the indoor microbial environment. Measurement techniques to determine the indoor microbial environment have moved from low to high resolution regarding the outcome quality of the exposure measurements, but are today still limited as to their potential in also quantifying exposure. NGS is nevertheless expected to largely improve our understanding of the indoor microbial environment. Accompanied by the development of bio-informatics and statistical techniques that help with the interpretation of the large amount of information provided by NGS techniques, these recent technological advances represent a potential revolution in better understanding the impact of the indoor microbiome on human health.