A review of indoor microbial growth across building materials and sampling and analysis methods

Abstract

Microorganisms from damp indoor environments are known to be one of the main causes of the degradation of indoor air quality and can be serious health hazards to occupants because of the production of airborne particles. Surfaces of building materials (plasterboard, mortar, etc.) are generally highly porous and rough. In damp environments, these materials can provide an environment favourable to proliferation and growth of microorganisms. Sampling of microbial communities on building materials, in addition to air sampling, is thus necessary to evaluate microbial proliferation indoors.The present paper aims to (i) summarise and compare the different methods used for sampling and analysing microbial growth on building materials and (ii) make a synthesis on the colonising microbial communities and the building materials parameters (humidity, chemical composition, pH, etc.) affecting their growth.With regards to methods, our investigations focused exclusively on studies dealing with building materials. When available, studies comparing the efficiency of methods on building materials were discussed. In-situ sampling campaigns were reviewed and the microorganisms identified on building materials were listed. Factors determining bio-receptivity of materials were also examined on the basis of studies performed on various types of materials (including building materials).The microorganisms the most frequently detected on indoor building materials are (i) fungi genera Cladosporium, Penicillium, Aspergillus and Stachybotrys, and (ii) Gram negative bacteria and mycobacteria. Some correlations between microbial genera/species and the type material can also be outlined. The water activity, the chemical composition, the pH and the physical properties of surfaces are parameters influencing microbial growth on materials. The particular behaviour of porous materials in terms of water sorption and the effect of water on microbial proliferation are underlined.In the future, the standardisation of methods for sampling, analysis and laboratory testing will be helpful in the assessment of microbial proliferation in building materials. Moreover, investigations on the impact of the material's mineralogy and its surface properties on growth will be necessary for a better understanding and predicting of microbial proliferation on these substrates.