3.1
Which are the critical sources of PM or
its components responsible for health
effects?
WHO
states: "Short-term epidemiological
studies suggest that a number of source
types are associated with health effects,
especially motor vehicle emissions, and
also coal combustion. These sources produce
primary
as well as secondary
particles, both of which have been
associated with adverse health effects.
One European cohort
study focused on traffic-related air
pollution specifically, and suggested
the importance of this source of PM.
Toxicological
studies have shown that particles originating
from internal combustion engines, coal
burning, residual oil combustion and wood
burning have strong inflammatory
potential. In comparison, wind-blown dust
of crustal origin [that is, from the Earth’s
crust] seems a less critical source."
More...
See also: General Issues
and Recommendations on Air Pollutants
3.2
What is the relationship between ambient
levels and personal exposure to PM?
Can the differences
influence the results of studies?
Personal exposure to PM
and its components varies from person
to person and is influenced by outdoor
sources as well as by indoor sources,
such as tobacco smoke.
On a population level
and considering variations over time,
there is a clear relationship between
the ambient
level of PM
and the level of personal exposure to
PM, especially for fine combustion particles.
Thus, measurements of PM in ambient air
can serve as a reasonable approximation
of personal exposure in time-series
studies.
Fewer studies have addressed
whether ambient
long-term PM
concentrations are a good indicator of
average/long-term PM exposure. Contributions
to personal PM exposure from smoking and
professional activities need to be taken
into account. More...
3.3
What is the health relevance and importance
of short-term exposure to high peak levels
or exposure in hot spots for PM?
Adverse health effects
have been documented after short-term
exposure
to peak levels of particulate
matter (PM),
as well as after long-term exposure to
moderate concentrations. However, the
impact of long-term exposure on public
health is probably larger than that of
short-term exposure to peak concentrations.
Long-term exposure to moderate levels
of fine
PM has been estimated to reduce life
expectancy by as much as several months.
Nevertheless, numerous deaths and serious
cardiovascular and respiratory problems
have been attributed to short-term exposure
to peak levels.
Areas near busy roads
where concentrations
of PM
components, such as elemental carbon and
ultrafine
particles, are particularly elevated
are referred to as “hot
spots”.
In urban areas, up to 10% of the population
may be living in these hot spots. The
public health burden of such exposures
is therefore significant. Unequal distribution
of health risks between groups of people
also raises concerns of environmental
justice and equity.
More...
3.
How are we exposed to Particulate Matter
(PM)?
