Environmental Health Criteria 214

HUMAN EXPOSURE ASSESSMENT
measurements have been conducted by independent observers using a
variety of samplers.
9.6.1 Air sampling for pollen
Several techniques exist for volumetric sampling of pollen grains
in indoor or outdoor air. Table 33 provides an overview of the devices
most commonly used for the sampling of pollen. Detailed information on
the different sampling devices has been published by the American
Conference of Governmental Industrial Hygienists (ACGIH, 1995). In all
cases, the pollen impacts a semi-solid surface (tape strip or glass
slide mounted with an adhesive). The main difference between the
devices is that the moving tape/slide impactors provide the
possibility of obtaining time-discriminated data, as opposed to the
stationary and rotating rod impactors. The sampling devices listed in
Table 33 may also be used to sample large fungal spores. Published
data on the validity of air sampling to estimate the exposure to
pollen are lacking.
9.6.2 Dust sampling for pollen
The sampling of settled dust to investigate the presence of
pollen grains or allergens derived from pollen can be conducted
exactly as for house dust mites and their allergens (see section
9.2.2) Dybendal et al. (1989) and Yli-Panula & Rantio-Lehtimäki (1995)
describe dust sampling techniques for pollens.
9.6.3 Available methods of analysis for pollen in air
Analysing air samples for pollen is commonly done by light
microscopy, but scanning electron microscopy is also used.
Immunochemical assays are not routinely used to assess the presence of
pollen allergens in air or dust samples. It should be recognized that
optically counted pollen grains may not relate to the pollen antigenic
activity because empty grains do not contain allergenic protein
material.
For light microscopic counting and identification of pollen,
staining of the sample is recommended. Staining can be done with basic
fuchsin and phenosafranin, which stain the exine of the pollen (i.e.,
the outermost portion of a pollen grain) red and dark pink
respectively. The choice of the dye depends on the type of sample to
be analysed. Pollen identification rests on the microscopic
appearance, using published keys for identification. (Faegri &
Iversen, 1989; Nilsson & Praglowski, 1992).
Immunochemical assays have been used to analyse samples of
settled house dust for the content of grass-pollen allergens
(ryegrass, Lol p I) by direct RAST (Platts-Mills et al., 1987). Birch
(Bet v I) and alder (Aln i I) pollen allergens have been analysed by
means of RAST-inhibition (Dybendal et al., 1989). Jensen et al. (1989)
have analysed outdoor air samples taken with a high volume sampler for
timothy and birch pollen allergens by means of a RAST-inhibition
assay. They found a strong correlation between the amounts of
allergens and pollen counts obtained with a Burkard trap. As indicated
above, immunochemical assays are not routinely used to measure pollen
allergens.
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