|
Indoor air pollution can
impact human health in a variety of ways, from irritant effects to
respiratory disease, cancer and premature death. Indoor air
pollutants can be elevated to levels that may result in adverse
health effects.
The health impacts of greatest significance include asthma, cancer,
premature death, respiratory disease and symptoms, and irritant
effects, according to the California Air Resources Board (CARB).
Modern society includes many tradeoffs, often characterized through
risk/benefit analyses.
Many indoor pollutants cause eye, nose, throat and respiratory tract
irritation. Aldehydes, as well as some other VOCs and oxidants, are
known mucous membrane irritants. Formaldehyde is the most commonly
identified irritant.
Acute effects of irritant chemicals can include respiratory and eye
irritation, headache, difficulty breathing, and nausea. Some of
these effects, particularly respiratory symptoms and eye, nose and
throat irritation can also be experienced with chronic exposure.
Terpenes, such as pinene and limonene, frequently used in cleaning
products for their favorable odor characteristics and solvent
properties, react with indoor oxidants to produce formaldehyde and
ultra fine particulate matter.
The impact on health depends on the toxicological properties of the
chemical and the exposure and absorbed dose an individual may
receive.
Particulate matter
Particulate matter (PM) is a complex mixture of very small particles
and other non-gaseous materials suspended in the air. Indoor
particle sources include combustion devices such as woodstoves and
fireplaces, and activities such as smoking, cooking, candle burning,
and vacuuming, all of which can produce PM with harmful components
similar to those found in outdoor air. Indoor particles also include
fibrous materials, pollen, mold spores and fragments, and tracked-in
soil particles. Pollens and mold can trigger allergies and asthma.
Tracked-in particles and some particles from combustion sources
become trapped in carpets and have been shown to include a mix of
toxic components such as polycyclic aromatic hydrocarbons (PAHs) and
lead.
Carbon monoxide
Carbon monoxide (CO) is a colorless, odorless gas that causes
flu-like symptoms (headache, nausea, lethargy) and inability to
concentrate, at lower exposure levels over periods of time. At very
high levels, CO can cause unconsciousness and even death. CO is a
product of incomplete combustion, emitted from sources such as
vehicle exhaust, gas and propane stoves and
furnaces, woodstoves, kerosene heaters and cigarettes.
Very high levels of CO occur relatively infrequently indoors.
However, a California study of death certificates showed that about
30 to 40 deaths occurred in California each year, on average, due to
unintentional CO poisoning. About two thirds of those deaths were
attributable to indoor sources.
The indoor sources most implicated in past CO poisonings were
combustion appliances,
such as malfunctioning or poorly tuned gas or propane furnaces and
stoves, and the improper use of charcoal grills and hibachis indoors
(contrary to warnings). Motor vehicles, such as those
unwisely left running in a garage, also have taken a substantial
toll. The relevant literature also indicates that other CO health
effects occur: hundreds of emergency room visits and thousands of
misdiagnosed flu-like illnesses due to non-fatal CO poisoning are
estimated to occur each year.
Toxic Air Contaminants and
Other Indoor Air Pollutants
Pollutants that may contribute to an increase in death or serious
illness can occur at elevated levels indoors due to emissions from
indoor sources. Some have been identified by CARB as toxic air
contaminants (TACs), air pollutants that don’t meet traditional
criteria for pollutants.
• Volatile organic compounds (VOCs), such as formaldehyde and
chlorinated solvents
are common in indoor air, and can exacerbate asthma and cause cancer
and irritant effects.
Some of these chemicals also have reproductive, developmental and
neurological effects at very high levels encountered infrequently in
non-industrial workplaces.
Indoor levels of formaldehyde, a pungent smelling gas, nearly always
exceed health based
guideline levels and acceptable cancer risk levels.
Formaldehyde is emitted from numerous indoor sources including
building materials (especially pressed wood products), composite
wood furnishings, personal care products, cosmetics, permanent
pressed clothing, combustion sources, and some new carpet pads and
adhesives.
• Environmental tobacco smoke (ETS) causes cancer, heart disease,
asthma episodes, middle ear infections in children, sudden infant
death syndrome and other adverse effects. Despite decreases in the
percent of smokers in the population and the statewide prohibition
of
smoking in workplaces, some individuals, especially children, are
still exposed to elevated levels of ETS in the homes and vehicles of
smokers.
• Polycyclic aromatic hydrocarbons (PAHs) – PAHs, emitted from
combustion sources such as cigarettes, woodstoves and fireplaces,
include a number of known or suspected carcinogens. They have been
found to adsorb onto particles in the air and deposit onto carpets,
from which they can be resuspended during vacuuming or other
activity.
• Radon daughters and asbestos are other known lung carcinogens
found indoors in some environments. Both radon and asbestos are
naturally-occurring, each emanating from specific types of soils.
Radon levels in are typically lower than mitigation guideline
levels, according to CARB. However the risk from radon cannot be
fully separated from that of tobacco smoke, and reduction of
exposure to tobacco smoke remains the primary mitigation approach.
Indoor asbestos is elevated only infrequently, typically during
remodeling of older buildings.
• Pesticides and metals – Dust from surfaces and carpets in homes
and schools have been shown to contain numerous residues of
pesticides, lead, mercury and other long-lasting contaminants that
have originated from outdoor activities, cigarettes, fireplaces and
other
sources. This is of special concern for very young children, who
spend time on the floor, and put their hands in their mouths,
because ingestion is often the primary route of exposure.
Pesticides are widely used, and some can cause adverse developmental
and neurological
effects at elevated exposure levels. Many pesticides registered for
use today are short lived, yet some are persistent in the
environment, lasting 20 to 30 years or more.
Recent studies indicate that some pesticides may be more persistent
in indoor environments,
because they do not experience the effects of weather and sunlight.
Biological Contaminants
Biological contaminants include substances of plant, animal, or
microbial origin, such as bacteria, viruses, mold, pollen, house
dust mites, animal dander; biological toxins such as endotoxins and
mycotoxins, and microbial volatile organic chemicals. These
biological
agents are abundant in both indoor and outdoor environments, but are
considered contaminants when found in undesired locations or at
elevated concentrations. Excessive exposure to these contaminants
can be associated with mucous membrane irritation (which may cause
symptoms such as itchy eyes, runny nose or sore throat) or
hypersensitivity reactions such as asthma attacks or allergy
symptoms in sensitive individuals.
Some individuals in persistently damp buildings report a variety of
symptoms such as headache, memory difficulties, vomiting, and
diarrhea; some researchers postulate that exposure to biological
toxins may induce such symptoms. In a 2004 Institute of Medicine
report scientists
found a number of symptoms and illnesses associated with dampness in
buildings and with indoor mold, although the scientific evidence was
not yet considered sufficient to confirm a causal relationship.
Many communicable diseases are primarily transmitted from person to
person in indoor air.
Common viral infections such as influenza, measles and chicken pox,
as well as emerging diseases such as Severe Acute Respiratory
Syndrome (SARS), are spread through inhalation of virus-contaminated
droplets produced when an infected person coughs or sneezes, or from
touching a surface or object contaminated with infectious droplets
and then touching one’s mouth, nose, or eyes (CDC, 2004).
Tuberculosis is a notorious infectious disease that is transmitted
in closely occupied spaces.
Building-related illness (BRI) refers to an illness for which the
specific cause can be identified within the building, such as
bacteria in ventilation systems causing Legionnaires’ disease, or
humidifier fever.
The usual causes of BRI include viruses, bacteria, and fungi. BRI
impacts can be substantial, and are of increasing interest as the
role of buildings in promoting diseases of biological contaminants
becomes better understood.
Indoor pollution causes substantial, avoidable illness and health
impacts – ranging from irritant effects to asthma, cancer, and
premature death – and costs billions of dollars each year. Because
there are numerous sources of pollutants in indoor environments, and
because people
spend most of their time indoors, exposure and the associated risk
are substantial.
Many agencies, professional groups, and organizations have taken
actions to reduce indoor pollution, but these have been piecemeal
and are not sufficiently effective in addressing the problem, says
CARB.
There are many actions that could be taken to significantly reduce
indoor emissions and exposure. If experience in controlling sources
of outdoor pollution is repeated relative to indoor sources,
many of these measures will be low cost and will provide substantial
health benefits. FSM For CARB’s full report on Indoor Air
Pollution, go to
www.arb.ca.gov/research/indoor/pcs/pcs.htm. |
