|
There are a number of
methods that can be used to prevent or reduce indoor air pollution,
but the most effective approach is to remove or reduce indoor
emissions by using building materials, consumer products, and
appliances that emit little or no air pollution.
Though more pollutants are emitted outdoors, once emitted, indoor
air pollutants are diluted much more slowly, due to the partial
trapping effect of the building shell. Additionally, indoor
emissions occur in closer proximity to people, and pollutants
emitted indoors have a 1000-fold greater chance of being inhaled
than do those emitted outdoors, according to the California Air
Resources Board (CARB), which has adopted a guide for control of IAQ
and IAP.
The most effective approach is to remove or reduce indoor emissions
by using building materials, consumer products, and appliances that
emit little or no air pollution.
The first thing CARB says is that ventilation (including proper
exhaust ducting) and public education are important components of a
strong indoor air quality improvement program.
• Source control is the most reliable approach to prevent indoor
pollution because it does not depend on building maintenance or
other human actions to assure healthful indoor air, says CARB.
Source control includes source substitution, source removal and
source modification.
Reduction at the source is most effectively achieved through use of
low- or zero emitting appliances, products or materials, or
reformulation of chemical products. For example, indoor formaldehyde
levels can be greatly reduced by using building materials that emit
little or no formaldehyde, instead of materials made with
urea-formaldehyde resins. Low emission product designs or
reformulations can usually be accomplished by the manufacturer, with
minimal impact on the consumer, often with only minor increased
costs.
• Ventilation is a standard engineering approach to assuring good
indoor air quality and comfort. Ventilation removes and dilutes
indoor contaminants, removes moisture from the air, which helps to
prevent mold growth, and removes effluents such as carbon dioxide
that lead to a stuffy
environment.
Natural ventilation through open windows and doors is the primary
ventilation route for residences, while mechanical ventilation,
using HVAC systems, is most common in commercial
buildings. Adequate and effective ventilation, and ducting of
exhaust from combustion appliances, are necessary for acceptable
indoor air quality, even when known air contaminants are minimized.
However, ventilation is not a complete solution to indoor pollution:
ventilation consumes energy, and some pollutants, such as
formaldehyde emitted from building materials, require years to
off-gas and are not completely removed by ventilation.
• Proper operation and maintenance of buildings is critical to
achieving and maintaining healthful air quality in buildings.
Ventilation systems should be maintained as intended and filters
replaced routinely to prevent soiling and the growth of mold and
bacteria in the ventilation system and in the occupied space.
Roof leaks that are not repaired promptly can lead to moisture
intrusion and mold growth.
Regular cleaning of indoor spaces with proper cleaning methods can
reduce biological contaminants, such as those associated with
insects and pollen, as well as persistent chemicals. Inattention to
proper operation and maintenance will not only lead to poor indoor
air quality, but can also prove more costly in the long term due to
increased costs to remedy the
larger problems that result.
• Public education is a key step for reducing Californians’
exposures to many indoor air pollutants. People’s choices and
activities have a major impact on their exposures to air pollution.
The use of various consumer products and activities such as
cigarette smoking and cooking can result in significant indoor
releases of pollutants. However, public education alone is not a
complete solution.
Some groups of the population cannot respond appropriately to take
needed action. For example, children cannot read or understand all
written information that is provided; elderly people living in group
settings cannot control the products used in their facility; and
low-income
families may not be able to afford safer alternatives.
• Air cleaning devices can also help improve indoor air quality;
however, their effectiveness is often limited. Air cleaning devices
include both central air filters and portable air cleaning
appliances.
Air filters are a normal component of mechanical HVAC systems in
public and commercial buildings. High efficiency particulate
arrestor (HEPA) filters, though not commonly used in
commercial buildings, are most effective at removing particles from
outdoor air as it is brought indoors. Air cleaning appliances are
usually portable units used indoors to remove particles from the
indoor air, although a few remove gases, and some remove both
particles and gases.
Mechanical air cleaners typically draw air through a filter while
electronic air cleaners remove pollutants with the use of an
electric charge.
Electrostatic precipitators (ESPs) and ionizers are the two major
types of electronic air cleaners on the market. The proper air
cleaner may help control airborne particles in some situations;
however, the limited scientific evidence available has not
documented any health benefits from air cleaners.
Problems in Schools
CARB reports that the primary problems of IAP found in schools
include:
• Inadequate ventilation with outdoor air during 40 percent of class
hours, and seriously deficient ventilation 10 percent of the time.
This is often due to teachers turning off HVAC systems because of
excessive noise.
• Formaldehyde air concentrations exceeded guideline levels for
preventing acute eye, nose, and throat irritation in about 4 percent
of the classrooms; nearly all classrooms exceeded guidelines
for preventing long-term health effects, including cancer.
• Obvious mold in about 3 percent of classrooms, and water stains
and other potential mold indicators in about one third of
classrooms, due to inadequate maintenance.
• Noise levels in all classrooms exceeded 35 decibels, a voluntary
standard for classrooms; one-half of the classrooms also exceeded 55
decibels, the level used for outdoor nuisance regulations.
Excess noise was primarily attributable to noisy ventilation
systems. Cal/OSHA’s workplace regulations related to ventilation,
moisture intrusion, and other aspects of building operation
and maintenance. Schools should conduct a self-assessment and
implement an indoor air quality management program, like that in
U.S. EPA’s IAQ Tools for Schools Program, recommends CARB.
Also consider:
• Develop and promote “Best Practices” for design, construction,
operation and maintenance of school facilities. The CHPS manuals
provide comprehensive guidance at no charge.
• Improve support (both funding and training) for school facilities
and staff.
Stable, long-term funding mechanisms are needed to assure adequate
and timely operation and maintenance.
Postponed maintenance often results in greater costs. Focused
training programs for administrators, facility managers, and
teachers are needed: those closest to the classroom are often not
aware of current “best practices” for operation and maintenance of
classrooms. FSM |
