Environmental Health Criteria 214

HUMAN EXPOSURE ASSESSMENT
Table 33. Overview of sampling techniques for airborne pollen grains a
Method Examples Sampling rate and ti
Rotating tape/slide impactors Burkard trap 10 litre/min, 7 days
Lanzoni sampler 10 litre/min, 7 days
Moving slide impactors Allergenco air sampler 15 litre/min, interm
Stationary slide impactors Burkard portable sampler 10 litre/min, 1-9 mi
Rotating arm impactors Rotorod sampler 47 litre/min, interm
a for detailed information see ACGIH (1995).
9.6.4 General considerations for pollen sampling
The source of indoor pollens can be considered as entirely
outdoors. Bringing flowers indoors might be a transient source, but
only about 10% of flowering plants and trees spread their pollen
through the air. Ventilation, footwear and clothing bring outdoor
pollens indoors. Yli-Panula & Rantio-Lehtimäki (1995) demonstrated
that antigenic activity indoors was lower, and peaked 3 weeks later
than outdoors. They inferred that transport by occupants and pets is a
more important vector for indoor pollen levels in the Finnish homes
they sampled. O'Rourke & Lebowitz (1984) sampled pollen in dust from
homes in the dry southwest of the USA (Tucson, Arizona). Higher
loadings were found in the dust samples closer to entrances. Both of
these studies, as well as others, indicate that indoor pollen
allergens may be a major cause of asthma, especially since significant
antigenicity can persist more than 2 months after pollen searches at
peak outdoors. Once indoors, if not physically removed, pollen grains
are protected from "weathering" which will denature the antigenic
proteins.
9.7 Summary
Bioaerosols includes a variety of microorganisms or their
components that can become airborne and inhaled. These include
viruses, bacteria, pollens, fungi, protozoa and algae as viable
organisms that can cause illness. Fragments or metabolic components of
bacteria and fungi along with protein structures contained in these
organisms as well as in the excreta and parts of insects, animals and
arachnids can cause allergenic reactions. This chapter focused on the
most ubiquitous bioaerosols commonly found indoors and contributing to
allergenic reactions: mites, fungi, bacteria and pollen. Methods and
strategies for sampling and analysing these agents in air and settled
dust are presented. Examples of how some of these parameters vary
indoors and outdoors across time and location are offered.
Exposure assessment for microbiologicals is as advanced, at this
time, as it is for many air contaminants. Personal samplers have not
been developed. In fact, many of the techniques for sampling
aerobiological agents have been adapted from instruments designed for
other purposes. The field is maturing as professional organizations
attempt to improve and standardize measurement methods, culturing and
analysis protocols and data reporting. These aspects are of critical
importance in comparing results reported by different investigators.
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