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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).

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