Chemistry Reference
In-Depth Information
and especially coarse particles. The largest infiltration factors are consistently
found for sulfate and black carbon. Volatilization and chemical decay may also
result in losses of specific components, including nitrates and organic components.
The large variability of PM
2.5
infiltration factors reported may further be due to
different composition of PM across locations. In locations with relatively high
sulfate and EC contributions, higher infiltration factors can be anticipated than in
locations with high nitrate and OC concentrations.
Keywords Indoor air, Infiltration, Outdoor, Particle size, Particles, Penetration,
Ultrafine
Contents
1 Introduction .................................................................................. 322
2 Example of Outdoor and Indoor Exposure: Augsburg Study ............................. 323
3 Model for Indoor Air Quality . .............................................................. 324
4 Empirical Studies on Indoor-Outdoor Relationships of Particles ......................... 328
4.1 Methodological Issues . . . ............................................................. 328
4.2 Indoor-Outdoor Relationships of PM
2.5
.............................................. 330
4.3 Indoor-Outdoor Relationships of Coarse (PM
10
-PM
2.5
) Particles . ................. 331
4.4 Indoor-Outdoor Relationships of Ultrafine Particles ................................ 331
4.5 Indoor-Outdoor Relationships of Specific Particle Components .................... 332
5 Conclusions .................................................................................. 334
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335
1
Introduction
Particulate matter (PM) has been identified in many studies as an important
component of the complex air pollution mixture responsible for various health
effects [
1
,
2
]. In many epidemiological studies, PM is characterized as the mass
of particles smaller than 2.5 or 10
m
m (PM
2.5
and PM
10
). This is largely because of
the availability of routinely measured concentrations of these particle metrics,
related to the promulgation of air quality guidelines in many countries, including
the European Union. It has, however, been hypothesized that the number of
ultrafine particles (UFP) may be another health relevant particle metric [
3
]. Never-
theless, there remains considerable uncertainty on the health effects of UFP
observed in epidemiological studies, largely related to measurement error
associated with characterizing exposure to UFP by central site outdoor
measurements [
4
,
5
]. A major component of measurement error is how well central
site outdoor concentrations are reflected in indoor air at the thousands of different
locations where the population actually is exposed for the majority of time. In
Western societies, subjects spend about 90% of their time indoors, of which a large
fraction in their own home. Hence indoor air quality is an important determinant of
personal exposure for many components.
