“Sick Building Syndrome” (SBS) occurs frequently in airtight buildings, but there are also a wide variety of factors that triggers the health problems. Numerous investigations have shown that micro-organisms may play an important role. Studies have shown that there was a high correlation between home dampness indicators and respiratory health problems. There were also indications that volatile organics from microbial cultures has an impact on cilial cells in respiratory airways.
Typically, a musty and earthy odour is the first sign of microbial activity. The microbial activities usually result in the decomposition of complex organic compounds into simpler compounds, and, in so doing, producing a wide range of by-products including the MVOCs. Some of these compounds are unique to micro-organisms; some can be the natural components of building materials that they grow on; and others are the same as common indoor air pollutants. The microbial volatile organics are so diverse that they encompass many chemical classes. In addition, there is no fixed MVOC pattern as the microbial emissions are different depending on the specific species, the substrates and the environment.
Determination of MVOCs is a useful way to check for the presence of mold. In many situations where spores of the micro-organisms are absent, the presence of unique MVOCs can be used to indicate the microbial activities.
Although many MVOCs have been reported in the literature, a lot of them are also known from indoor sources such as furnishings and building materials. In order to distinguish microbial volatiles from other sources, it is of utmost importance to choose compounds that are unique to microbial origin to determine the presence of microbial activities. Currently, other laboratories have used a list of VOCs as markers of the microbial activities, however, more often only a few of them were found in the air sample and the results are not conclusive. When MVOCs are present, there are often a number of higher molecular weight microbial compounds present. The detection of these compounds (listed in Table 2) in conjunction with some of the compounds in the target list will give a clear indication of microbial growth.
Normally, the concentrations of MVOCs in indoor air are very low. The use of a solvent extraction technique will often lead to false negative results. The thermal desorption GC/MS technique offers full scan capability with a thousand-fold increase in sensitivity. Not only can MVOCs be detected, but sesquiterpenes from micro-organisms activities can also be identified. Below is a summary of the method used and the MVOCs/Sesquiterpenes that are targeted for: