Evidence for Adverse Health Effects from:
Short-term exposure to indoor air
pollution
Whether specific pollutant causes adverse health effects or
not depends on many factors like: characteristics of the
pollutant, air concentration, duration of exposure. Usually
adverse health effects do not manifest immediately since
there is a cumulative dose response, and they vary among
people since the dose-response relationship is not linear
and equal dose causes different effect
on different subjects.
Short-term exposure effects might appear soon after a single
high-dose exposure to one or more air pollutants. Usually in
such cases the cause is easily identifiable (i.e. spill of
aggressive chemicals, or excessive dust, mold growth, etc.)
and with ceasing exposure to the agent the symptoms
disappear.
Other effects may be manifested with different lag time
(27), often as
non-specific, mild symptoms, which are very
similar to the symptoms of a common flu, or increased stress
levels (24,
26,
32, 33). This makes it difficult to
differentiate the real cause and to tackle it appropriately.
Most primary care physicians lack training in and knowledge
of clinical recognition, management and avoidance of such
exposures (30), thus it is important to take patient's
environmental exposure history.
Combination of more pollutants in one place is associated
with increased occurrence of all symptoms (34,
22) and
adverse effects occur even at very low levels (22).
Women report symptoms more frequently than men (33,
35, 36,
37, 38).
Long-term exposure to indoor air pollution
Evidence for adverse health effects caused by long-term
exposure to air pollution is available for more than a
decade. One of the first studies to show association between
exposure to air pollution and mortality rates is the famous
Harvard Six Cities Study (1). The results have been
confirmed in 1995 by American Cancer Society's Cancer
Prevention Study II. In 2002 New York University together
with American Cancer Society conducted one of the most
comprehensive studies to date on long-term effects of air
pollution on mortality rates. The study "found a progressive
increase in death rates from cardiopulmonary disease, lung
cancer, and all causes of death combined associated with
higher levels of particulate air pollution" (2).
American Heart Association Journals have published numerous
of studies from all over the world showing that particulate
air pollution is associated with increased cardiovascular
morbidity and mortality (3, 4, 5, 6, 7, 8, 9, 10).
In Australia there are studies from Brisbane (11), Sydney
(12) and Melbourne (13) showing association between air
pollution and morbidity (hospital admissions) and mortality.
A cohort study in Netherlands traced 5,000 people form 1986
to 1994. The researchers found that people living near major
roads with higher air pollution were at increased risk of
premature death from cardiopulmonary diseases (14).
An explanation for the higher cardiovascular morbidity and
mortality caused by air pollution can be found in a study
from Belgium (15), which provides evidence that ultrafine
particles enter into the bloodstream from the lungs and than
are distributed to different organs.
Ability of ultrafine particles to enter into bloodstream
from the lungs has been proved from a study with laboratory
rabbits (16). Researchers found that atherosclerosis - a
disease associated with consumption of fat food - was
accelerated by exposure to fine particles.
As we all know,
rabbits do not eat fat food at all, but nevertheless they
got the same condition after being exposed to fine
particles.
Even short term exposure to ultrafine particles can cause
adverse health effects. Researchers found that short term
exposure to ultrafine particles concentrated from Boston's
air induced an inflammatory reaction in the lungs of rats
(17).
It is important to be aware that adverse health effects are
registered even at low levels of pollution, which are below
current limit values from air quality guidelines. In
recognition of this fact American Thoracic Society has
extended the list of adverse health effects of air
pollution. Apart of clinical outcomes they have included
decreased quality of life and also sub-clinical symptoms,
which can affect people's daily activities (18).
Children exposed to air pollution experience adverse health
effects even at pollution levels which are below current standards.
Several studies from different countries (19, 20, 21),
including eight USA cities, report reduced lung-function
growth in children exposed to air pollution. Researchers
conclude that impairment of lung-function growth could lead
to "lower lung-function parameters in adulthood,
predisposing to chronic pulmonary diseases" (21).
Evidence for Indoor Air Quality Impact on
Productivity
It is common sense that people perform better in better
working environment. Although that the relationship between
indoor air quality and productivity has not been evaluated
thoroughly, there is evidence from different studies showing
the positive effect of improved indoor air quality on productivity
(performance) of the staff. (39, 40, 41, 42, 43).
Researchers found that with reduction of the number of
airborne particles performance of the staff improves and
reports of adverse health effects decrease. (39, 40, 41, 42,
43). On the other hand low rate of outdoor air, i.e. higher
number of airborne particles in the air indoors, is
associated with decreased productivity of the staff and an
increase of short-term sick leave (41).
