CA Air Resources Board
California Portable Classrooms Study
This page updated April 6, 2007
The Air Resources Board (ARB) and Department of Health Services (DHS) completed a comprehensive study of the environmental health conditions in portable (relocatable) classrooms. This study investigated classrooms in kindergarten through 12th grade public schools and included a large representative sample. A number of environmental problems were found in classrooms throughout California. The Report to the California Legislature: Environmental Health Conditions in California's Portable Classrooms has been submitted to the Legislature, and is available for download below:
Final Report to the Legislature, November 2004
Other related documents are also available.
Highlights of the Report to the Legislature
ENVIRONMENTAL HEALTH CONDITIONS
in CALIFORNIA’S PORTABLE CLASSROOMS
The Air Resources Board (ARB) and Department of Health Services (DHS) recently
completed a comprehensive study of the environmental health conditions in portable
(relocatable) classrooms, as required under California legislation (AB 2872, Shelly,
2000). This study investigated classrooms in kindergarten through 12th grade public
schools and included a large representative sample: two portable classrooms and one
traditional classroom were evaluated at several hundred schools throughout the state.
A number of environmental problems were found in classrooms throughout California.
This fact sheet briefly summarizes the findings and recommendations of the study. For
the full report, please visit http://www.arb.ca.gov/research/indoor/pcs.pcs.htm.
California Environmental Protection Agency
Air Resources Board
Arnold Schwarzenegger, Governor
Environmental Health Conditions in California’s Portable Classrooms
The report identifies and addresses a number of environmental problems that were frequently found in classrooms throughout California. These problems were found in both portable (relocatable) and traditional (site-built) classrooms; however, some of the problems were found more frequently in portable classrooms.
The primary problems identified in the PCS study include:
♦ Inadequate ventilation with outdoor air.
Substandard amounts of outdoor air were
measured in classrooms during 40 percent of
class hours, and seriously deficient ventilation
was found 10 percent of the time. The causes
included teachers turning off HVAC (heating,
ventilating, and air-conditioning systems)
because of excessive noise; closed or blocked
outdoor air dampers; off cycling of the HVAC;
inadequate HVAC capacity; and other factors.
♦ Classroom noise too high. About one-half of
the classrooms exceeded 55 decibels, the level
used by many communities in the state for their
outdoor nuisance regulations, and most
exceeded the current “best practices” guideline
of 45 decibels. Major noise sources are
primarily noisy HVAC equipment, noisy lighting,
and noise from nearby outdoor activities.
♦ Poor thermal comfort. Temperature and
humidity levels were outside the range given by
professional standards for thermal comfort in
about one-fourth of the classrooms. Causes
appeared to be related to improper HVAC
system control and/or inadequate capacity.
♦ Indoor formaldehyde levels. In 4 percent of
the classrooms, air concentrations of
formaldehyde exceeded the guideline level for
preventing acute eye, nose and throat irritation.
Nearly all classrooms exceeded formaldehyde
guidelines for preventing long-term health
effects, including cancer. These findings are
largely due to the widespread use of
formaldehyde-containing building materials and
furnishings, and inadequate ventilation.
♦ Moisture problems. Water stains, excess wall
moisture, and other indicators of potential mold
were found in about one-third of classrooms.
Investigators found visible mold in about 3% of
classrooms; and musty odors were reported by
69% of teachers. These conditions are often
attributable to inadequate maintenance.
♦ Toxic residues in floor dust. Lead, arsenic,
and numerous pesticide residues were
measured in classroom floor dust. These
residues are a concern because they can be
inhaled, ingested, or absorbed through the skin
by children, especially very young children who
sit on the floor and put their hands in their
mouths. The source is generally tracked in dirt
from outside, and pesticides applied indoors or
near the building.
lighting. In about
one-third of the
lighting was below
the level given by
Dirty air filters can reduce airflow.
Environmental Health Conditions in California’s Portable Classrooms
Sixteen recommendations are discussed in the report. These can be grouped into four general approaches
needed to remedy and prevent the problems found in California public schools:
• Direct and assist schools to comply with State regulations, especially workplace regulations (Cal/OSHA)
related to building operation and maintenance;
• Develop and promote “Best Practices” for design, construction, operation, and maintenance of school
• Improve support (both funding and training) for school facilities and staff;
• Establish needed guidelines and standards for school environmental health that are specifically
protective of children.
The recommendations are split between Group 1 (“high priority, high benefit” actions) that can be achieved
in the near term at relatively low cost, and Group 2, also priority issues, but requiring a longer timeframe
and/or more substantial resources.
The Group 1 recommendations (“high priority, high benefit” actions) are:
1. Schools, districts, and the state should ensure
that all school buildings meet all relevant
state regulations, especially the Cal/OSHA
workplace regulations regarding ventilation,
sanitation and water intrusion, and illness and
2. Schools and school districts should conduct
“self-assessments’ of basic health and safety
conditions. This approach has been
successfully piloted by the Los Angeles Unified
School District in their Facility Self-inspection
Program (included in the report and available
on the web).
3. The State should require schools to develop
indoor environmental quality management
plans. The U.S. Environmental Protection
Agency’s IAQ Tools for Schools Program
provides guidance and free kits to accomplish
4. The State should establish a policy to
incorporate “Best Practices” into the
design, construction, operations, and
maintenance of new California schools,
especially the measures developed by the
Collaborative for High Performance Schools
(CHPS). The CHPS Best Practices Manuals
provide broad guidance for measures that will
improve schools while also saving energy and
reducing long-term costs.
5. State-level review, by the Division of the
State Architect, of the designs for new
schools should be expanded to include
elements such as ventilation systems and
building materials, in addition to current
elements such as fire and life-safety
6. Classrooms, especially portables, should
be sited correctly, away from busy roadways,
and with proper drainage.
7. The State should implement an interim new
classroom requirement for maximum noise
levels at 45 decibels, unoccupied, until a
specially convened task force can determine
an appropriate level for California schools (see
Group 2 recommendations below).
Water leaks in roofs and near HVAC units are
common causes of moisture and mold problems.
Environmental Health Conditions in California’s Portable Classrooms
Group 2 recommendations (longer timeframe and/or more substantial resources) specify that:
8. The State and school districts should assure
stable, long-term funding mechanisms and
sources for both construction and preventive
maintenance; currently funding fluctuates from
year to year, especially for the Deferred
9. The State should develop and offer focused
training programs for school facility
managers, custodial staff, and teachers, in
cooperation with interested organizations;
those closest to the classrooms often are not
aware of current “best practices” for operation
and maintenance of classrooms. A concerted,
ongoing training program could go far to
improve conditions in classrooms.
10. Integrated Pest Management Programs
should be implemented at all schools.
11. Older portable classrooms should be
retired when they become unserviceable or do
not provide an adequate learning environment
12. The State and school districts should develop
and require full new building commissioning
13. The State should improve its school
facilities database, as there are currently no
complete databases on the condition, location,
or even number, of school buildings.
14. The State should convene a task force of
experts to develop a California indoor noise
guideline or standard for K-12 schools.
15. The State should develop chemical exposure
guidelines or standards for classrooms that
are protective of children and teachers.
16. Portable classrooms should be re-designed
from the ground up. Several groups are
producing new prototypes that use an
integrated “whole building” approach; these
should be supported through the demonstration
phase to evaluate design changes that
provide substantive improvements over older
Vehicle traffic near classrooms can lead to exposure to harmful air pollutants.
For more information, go on-line to http://www.arb.ca.gov/research/indoor/pcs/pcs.htm.
See especially Appendix VI for specific guidance to schools.
© State of California, 2004
Board Meeting Slide Presentation, Notes and Handout
Final Research Study Report
From CALIFORNIA PORTABLE CLASSROOMS STUDY
PROJECT EXECUTIVE SUMMARY (with respect to mold and moisture):
"With regard to moisture and mold indicators, over two-thirds (69%) of teachers in portable
classrooms reported that they noticed musty odors at times. Less than half (43%) of these
teachers reported current or previous leaks or floods in the room, the majority of the leaks
coming from the roof (27% of all portables). Visible mold, either currently or previously, was
reported by 11% of portable classroom teachers. For traditional classrooms, teachers reported
the presence of musty odor less often (58%, p < 0.01), but they reported previous flooding
significantly more often (47%, p < 0.05)." (p.8)
"In addition, portable
classrooms were again more likely to have a metal roof (28.5% versus 2.5%) and to have water
stains on the floor (18.1% versus 2.0%); however, portable classrooms were more likely to have
carpets, so would be more likely to have water stains on a carpeted floor."(p.11)
"The estimated distribution of the height of the foundation skirt for portable classrooms is as
follows: 42.6% are less than 2” above the ground, 22.2% are from 2” to 12” above ground, and
35.2% are over 12”. Foundation skirts close to the ground have been reported to be more
susceptible to surface water contact and wicking of water up wall materials, resulting in mold
and moisture problems." (p. 12)
"The air filter for the HVAC unit in portable classrooms was more likely than traditionals to
have a light or medium loading of dirt.
• During the Phase II inspections, portable classroom HVAC units were less likely to have
clean condensate drain pans and lines (30.0 versus 56.7%), and were more likely to fail the
“drain test” used by the inspector to test for blockage (58.5 versus 12.4%).
• Also, the air intake was blocked on the air handling units more often for portable classrooms
than for traditional classrooms (10.8% versus 2.7%)."(p. 12)
"Most types of environmental complaints (roof leaks, air quality/odor, mold, temperature,
noise) were reported more often for portable classrooms; an exception was plumbing leaks,
which were more common in traditional classrooms."(p.20)
"HVAC filters in portable classrooms showed a higher percentage of
mildew or mold, dirtier condensate drain pans, clogged drains, and standing water."(p.21)
had relative humidity measurements above 60% more of the time than traditional classrooms;
such levels are not only uncomfortable, but can lead to increased moisture and mold problems,
increased dust mite populations (allergy and asthma triggers), and other problems." (p.22)
"Airborne pollens and spores (primarily fungi) were found at higher levels outdoors than
indoors, as expected. Typically indoor levels of fungi are elevated primarily in cases of extreme
mold or biological contamination. However, classroom wall, floor, and ceiling moisture
measurements indicated excess moisture in building materials in about 17% of the classrooms,
indicating potential mold problems in those locations. Traditional classrooms had excess wall,
floor, and ceiling moisture more often than portables, but portables were reported to experience
roof leaks more often, and over two-thirds of the teachers in portables reported musty odors at
From the above discussions of significant results, it is clear that there are differences in
environmental factors between portable and traditional classrooms. Most importantly, some of
both types of classrooms exceeded many of the environmental standards and guidelines available
for judging the state of the environmental conditions in classrooms. Further analyses of this very
rich data base will likely reveal other factors that could prove useful for further identifying
sources and measures to be taken to reduce their potential effects." (p.25)
We have also developed a web page (http://www.arb.ca.gov/research/health/school/school.htm) for school administrators and others involved in school environmental health and air quality issues. It includes a short (two-page) advisory to schools on actions they can take now to improve the environmental conditions in their classrooms, plus many web links to steer them to useful information and checklists.
The Air Resources Board and Department of Health Services have developed recommendations to assist schools in reducing their indoor formaldehyde concentrations.
"Remedies for Reducing Formaldehyde in Schools"