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Scientists Find Evidence of Link Between Outdoor Ozone and Building-Related Health Symptoms
by Source: Berkeley Lab http://www.physorg.com/news120325891.html
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Air filters used
in the ventilation systems of some building may play a role in the prevalence
of building-related symptoms (BRS), which is more commonly known as sick
building syndrome.
www.physorg.com
A team of researchers at the U.S. Department of Energy’s
Lawrence Berkeley National Laboratory ( Berkeley Lab) has found evidence that
the prevalence of building-related symptoms (BRS) increases with increasing
outdoor concentrations of the pollutant ozone. They have also discovered that
the type of air filter that some buildings use in their ventilation systems
may also play a role in the prevalence of BRS.
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BRS, more commonly known as sick building syndrome, is a set of health
symptoms reported by office workers which improve when they leave the work
environment. The symptoms can include irritation of the eyes, nose, throat,
respiratory tract, and skin, as well as headache and fatigue.
This is the first epidemiological evidence from a field study of a link
between ambient ozone levels and BRS. It is also the first field evidence
linking BRS to a specific filtration technology used in large buildings.
The study was conducted by Michael Apte, Ian Buchanan, Mark Mendell, and Anna
Mirer of Berkeley Lab’s Environmental Energy Technologies Division in
collaboration with the U.S. Environmental Protection Agency (EPA), which
collected the data.
Results originated from the team’s analysis of data from an EPA study called
BASE (Building Assessment Survey and Evaluation), in which 100 U.S. office
buildings were studied for one week each in either= the summer or winter
between 1994 and 1998. That study included surveys of office workers and
their self-reported health conditions, weather and workplace data, and
environmental conditions in and around the buildings.
(No data on indoor or outdoor ozone levels was collected during the EPA’s
BASE study. Ozone data used in this analysis was obtained from the historical
records of ambient air quality monitoring stations near the BASE buildings
during the same time periods as the BASE buildings were studied.)
According to Apte, “Based on patterns of associations between
building-related symptoms and certain volatile organic compounds indoors, we
hypothesized that increasing levels of outdoor ozone would lead to higher
prevalence of building-related symptoms among the occupants within a
building.”
Their analysis of the BASE data shows that the prevalence of upper
respiratory symptoms in a building increases linearly with increasing
concentration of outdoor ozone. It also shows that the indoor concentrations
of formaldehyde, acetaldehyde, and organic acids including pentanal, hexanal
and nonanal increased with increasing outdoor ozone. All of these are known
sensory irritants, and formaldehyde is a known carcinogen.
From a long history of previous studies in the laboratory, scientists know
that ozone can cause ill health in humans—this is why it is regulated as an
outdoor pollutant. More recent lab studies have also proven that ozone reacts
with organic molecules typically found indoors to produce short-lived
chemicals that are irritating, and may be toxic or carcinogenic if a human is
chronically exposed to them. For example, formaldehyde and acetaldehyde are
produced when ozone reacts with commonly found organic chemicals; both are
irritants.
Lab studies suggest that these chemicals may have a large impact on indoor
air quality. However, until the current study, there has been no direct field
evidence of a correlation between outdoor ozone and a health condition inside
a building.
In a second paper, the researchers report on how different types of building
air filters can affect the prevalence of BRS symptoms. Data from a subset of
buildings in the BASE study showed strong statistical connections between a
certain type of air filter and increased BRS. Air filters are made of
different types of materials, including polyester/synthetic fibers,
fiberglass, natural filters made of cotton or cellulose, or natural-synthetic
blends. Their purpose is to remove particles and other contaminants from the
building’s air.
The team found that the combination of higher outdoor ozone levels and the
use of a polyester or other synthetic filter correlates with a statistically
significant increase in the prevalence of BRS compared to other types of air
filters. This filter showed a significant association with lower and upper
respiratory symptoms, cough, sore eyes, fatigue, and headache.
By contrast, far fewer symptoms were reported in buildings with high ozone
and fiberglass filters, or in situations where the building used
polyester/synthetic filters and the outdoor air had lower ozone
concentrations.
The research suggests that replacing the polyester/synthetic filter could
have a major positive impact, reducing BRS prevalence by up to 75 percent in
buildings with high outdoor ozone concentrations, and by up to 39 percent in
lower ozone environments. “The study estimated that removing both risk
factors—higher ozone in outdoor air and polyester/synthetic filters—could
reduce BRS by 26 to 62 percent,” says Apte.
Apte notes that the results of both studies require further verification.
“This research is a first step, and it needs to be replicated in other
studies with a statistical design specifically to address the ozone-symptom
association and with accurate information on filters and ozone levels. The
strongest studies would involve controlled interventions on these two
factors,” he says.
“However, if future research confirms these results, then we may have a path
toward reducing building-related symptoms as well as illness caused by
chronic exposure to ozone in the indoor environment, through the use of ozone
removal technologies in ventilation systems.”
Two papers describing the results will be published in the journal Indoor Air
— “Outdoor Ozone and Building Related Symptoms in the BASE Study,” by M.
Apte, I. Buchanan, and M. Mendell, and “Air Filter Materials, Outdoor Ozone
and Building-Related Syndrome in the BASE Study,” by I. Buchanan, M. Mendell,
A. Mirer, and M. Apte. The work was funded by the Centers for Disease
Control—National Institute for Occupational Safety and Health.
Source: Berkeley Lab
http://www.physorg.com/news120325891.html
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