Dampness and Mould - WHO guidelines for indoor air quality - PRWeb

BUILDING DAMPNESS AND ITS EFFECT ON EXPOSURE
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2.4.3 Measurement of indoor allergens
Antibody-based immunoassays, particularly enzyme-linked immunosorbent
assays, are widely used to measure aeroallergens and allergens in settled dust in
buildings. These assays involve use of antibodies specific to the target allergen
and an enzymic reaction with a substrate for detection. In radioimmunoassays,
radiolabelling is used for detection. The house dust mite allergens Der p I,
Der f I and Der p/f II have been widely investigated and the methods well described
(Luczynska et al., 1989; Price et al., 1990; Leaderer et al., 2002). Methods
for assessing exposure to allergens from rodents (Swanson, Agarwal, Reed, 1985;
Schou, Svendson, Lowenstein, 1991; Hollander, Heederik, Doekes, 1997), cockroaches
(Pollart et al., 1994) and storage mites (Iversen et al., 1990) have been
published.
Methods for measuring fungal allergens are not widely available, mainly because
of difficulties in manufacturing and standardizing fungal allergen extracts
(see section 2.3.1). Nonetheless, some enzyme-linked immunosorbent assays
have been described in the literature, and a commercial assay is available for A.
alternata allergen (Alt a I). A comparison of several monoclonal and polyclonal
antibody-based assays for measuring Alt a I (including a commercially available
method) showed, however, wide disparity (Barnes et al., 2006). It is therefore unclear
whether these assays provide valid estimates of the true Alternaria allergen
concentrations in indoor samples.
2.4.4 Strategies for monitoring exposure
In addition to questionnaires, personal or environmental monitoring is commonly
used for exposure assessment. Although monitoring can potentially result
in a more valid, accurate assessment, this may not always be the case. Validity is
strongly dependent on the sampling strategy chosen, which in turn depends on a
large number of factors, including: the type of exposure and disease or symptoms
of interest; whether the health outcomes are acute or chronic (e.g. exacerbation
versus development of disease); whether the approach is population- or patientbased;
suspected variations in exposure over both time and space and between
diseased and reference populations; the methods available to assess exposure;
and the costs of sampling and analysis.
2.4.4.1. What should be measured?
With regard to health problems associated with indoor air, many exposures
should be considered, as it is often unclear which microorganisms or agents
are causing the symptoms or diseases. Some studies are conducted specifically
to assess which exposures are contributing to the development of symptoms. In
practice, both funding and the availability of methods for measuring agents are
limited, as many methods are not commercially available and are used only in
research, severely limiting the possibility of measuring all agents of interest.