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9
ASTHMA AND NONRESIDENTIAL
INDOOR E~viroun~ents
M any cross-sectional epidemiologic studies document an
association of asthma diagnoses or asthma symptoms with as-
pects of the residential environment, such as dampness or mold.
In contrast to residences, nonindustrial work buildings often have
large numbers of occupants in whom the epidemiology of asthma
can be studied in relation to the built environment. Several lines
of evidence suggest the efficiency of pursuing indoor environ-
mental factors in relation to asthma among office workers, school
staff, and students.
This chapter briefly reviews the scientific literature regarding
asthma and nonresidential indoor environments primarily of-
fice buildings and schools. Industrial environments, which may
expose workers to a wide variety of allergens and irritants ca-
pable of inducing asthma (Chan-Yeung, 1995), are outside the
scope of this chapter and report.
BUILDING-RELATED ASTHMA
New-onset asthma caused by specific building environments
has been investigated infrequently. Case reports of office build-
ing-related asthma with a clear work-related pattern exist, and
the causes were related to humidifiers or the biocides used in hu-
midifiers (Finnegan and Pickering, 1986; Robertson and Burge,
316
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ASTHMA AND NONRESIDENTAL INDOOR ENVIRONMENTS 317
1985~. Epidemic asthma occurred in a printing factory in associa-
tion with a contaminated humidifier (Burge et al., 1985~. The most
compelling description of office building-related asthma found
that employees of a county social services agency in Denver had a
2.9-fold rate of physician-diagnosed asthma arising since build-
ing occupancy compared to employees of a comparable subur-
ban social service agency (Hoffman et al., 1993~. The Denver
workers reported excess shortness of breath and chest tightness,
and 36% of Denver employees with preexisting asthma reported
exacerbation of their asthma in relation to building occupancy, in
contrast to none of the preexisting asthma cases in the suburban
county agency. Peak expiratory flow measurements of a sentinel
case fell markedly over the course of time at work, with recovery
within an hour outside the office building. Bronchial reactivity
measurements from serial methacholine challenge tests showed
improvement to the normal range within two to three months of
assignment to another building; recurrence of bronchial hyperre-
activity with reassignment to the implicated building; and partial
resolution with removal for the second time. In addition to a 4.9-
fold excess of asthma with onset or exacerbation since building
occupancy, cases of hypersensitivity pneumonitis and other in-
terstitial lung disease occurred among occupants of the implicated
building. In this investigation, the suspected cause was
bioaerosols associated with below-grade moisture incursion from
the posterior wall that was built into an earthen bank.
Although the few publications discussed above document the
phenomenology of building-related asthma, little information ex-
ists regarding the contribution of building-related asthma to the
increasing asthma burden in the United States or elsewhere. Sev-
eral state health departments solicit physician case reports of oc-
cupational asthma for the purpose of state- or federally funded
surveillance. Data from four states reported to the National Insti-
tute for Occupational Safety and Health (NIOSH) for 1993-1995,
documented 86 physician-diagnosed cases attributed to indoor
air quality deficiencies, without other specific cause, accounting
for 8% of all occupational asthma cases recognized by reporting
physicians (Romero lajosky et al., l999~. Michigan, Massachusetts,
and Connecticut supplied data over a longer time, which docu-
ment increasing proportions of all reported occupational asthma
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318
CLEARING THE AIR
cases attributable to indoor environmental quality, up to 25% (un-
published reports from Carolyn lean Dupuy, Connecticut Depart-
ment of Public Health, Respiratory Disease and the Indoor Envi-
ronment, sent to NIOSH by emai! on May 13, 1999; from Ruth
Vanderwaals, Michigan Department of Public Health sent by
emai] on March 22, 1999; and from Letitia Davis, Massachussetts
Department of Health, sent by emai] on March 6, 1999~.
Another source of physician case reporting is the data base of
the Association of Occupational and Environmental Health Clin-
ics (AOEC). An unpublished report indicates that from 1991 to
1996, 15% of the 542 occupational asthma cases seen in the report-
ing members of largely academic clinics were related to indoor
air exposures, with the annual proportion increasing from 6% in
1991 to 30°/O in 1996 (Hunting, 1999~. Half of the cases of reported
asthma-reactive airways dysfunction syndrome (RADS) from pri-
mary and secondary schools and vocational schools in this data
base were attributed to indoor air exposures. These data must be
interpreted with caution because the number and location of re-
porting clinics varied from year to year and the numbers are likely
influenced by the characteristics of the responding facilities.
This limited information from practitioners reporting to pub-
lic health agencies or their occupational health association sug-
gests that physicians are seeing patients with work-related pat-
terns of asthma symptoms or objective measurements for which
they are unable to identify specific causes apart from alleged poor
indoor air quality. Investigations in response to these reports by
public health agencies have been limited by lack of knowledge
about what agents to measure in evaluating hazards for asthma
or for less specific indoor air quality (IAQ) complaints.
Attribution of asthma and asthma symptoms to specific build-
ing environments by the lay public far exceeds physician recogni-
tion of building-related asthma. One source of data regarding
public concerns about building contributions to asthma are the
requests from employees or management for Health Hazard
Evaluations, a mandated service program of NIOSH. Since the
late 1970s, after the energy crisis and changes in ventilation codes,
health hazard evaluations coded as "indoor air quality requests"
from office and school employees have increased persistently in
numbers and proportions of all requests. Of the 100-200 IAQ re
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ASTHMA AND NONRESIDENTAL INDOOR ENVIRONMENTS 319
quests received each year since 1990, the proportion mentioning
asthma in the written request increased during the 1990s to 14%
in 1998; the proportion mentioning any chest symptom increased
to 46% in 1997-98. Among IAQ requests mentioning asthma as a
health concern to be investigated in the health hazard evaluation,
a substantial minority 43% come from school staff, manage-
ment, or unions representing teachers.
Most office workers do not attribute chest symptoms to their
building environments. Preliminary analyses of questionnaire in-
formation from occupants of 29 buildings surveyed in the U.S.
Environmental Protection Agency's (EPA's) Building Assessment
and Evaluation Study (Brightman et al., 1997), revealed that the
median prevalence of occupants reporting frequent work-related
shortness of breath was 2%. An unpublished NIOSH report evalu-
ating a series of buildings selected without regard to indoor air
quality complaints indicated a maximum prevalence of 8% (Sieber
and Godwin, 1998~. In contrast, one-third of 80 office buildings
studied by NIOSH in 1993 in response to health hazard evalua-
tion requests had prevalences of frequent work-related shortness
of breath greater than 8%, ranging up to 24% (Malkin et al., 1996~.
In conclusion, most buildings in which occupants have IAQ com-
plaints probably do not have excesses of respiratory disease, but
a substantial subset of "complaint" buildings may have occupants
who associate their chest symptoms with building occupancy.
The NIOSH experience with indoor air quality investigations
in 1993 gives some epidemiologic leads regarding building-re-
lated asthma and its causes (Sieber et al., 1996~. Among 2,435 OC-
cupants of 80 office buildings classified according to whether
moisture was found in the heating, ventilation, and air-condition-
ing (HVAC) system, the prevalence of physician-diagnosed
asthma arising since building occupancy was 61% higher in build-
ings with HVAC moisture, and the prevalence was doubled of
having three of four chest symptoms (cough, shortness of breath,
wheezing, and chest tightness) at least once per week in the last
month that improved away from work (Table 9-1~. In logistic
analyses controlled for age and gender, postoccupancy asthma
was associated with dirty HVAC filters, debris in the air intake
system, and renovation with drywall within the previous three
weeks; daily surface cleaning with wet methods appeared protec
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320
CLEARING THE AIR
TABLE 9-1 Health Conclition Prevalence (%), by Moisture Status of HVAC
Among 2,435 Occupants of DO Office Builclings with IAN Complaints
Moisture Moisture
Health Condition Present Absent Range
Any physician-diagnosed asthma 11.7 11.6
Postoccupancy asthma 3.7 2.3 0-33.3
Chest symptomsa 4.1 1.8 0-33.3
aThree of four (cough, shortness of breath, wheezing, chest tightness) occurring
>1/week in last month and improving away from work.
SOURCE: W. Karl Sieber, Division of Surveillance, Hazard Evaluations, and Field Studies,
National Institute for Occupational Safety and Health, written communication to Kathleen
Kreiss, March 8,1999.
TABLE 9-2 Relative Risks by Health Conclition for Environmental Factors
Environmental
Variable
Postoccupancy
Asthma
Multiple
Chest Symptoms
Dirty filters 2.0 a 1.9 a
Air intake debris 2.0 a 3.1 a
Recent renovation with drywall 2.5 a 1.1
Ceiling panels 3.2 3.4
Daily surface cleaning 0.5 a 0.7
apt< .05.
SOURCE: W. Karl Sieber, Division of Surveillance, Hazard Evaluations, and Field Studies,
National Institute for Occupational Safety and Health, written communication to Kathleen
Kreiss, March 8,1999.
five in logistic regression models (Table 9-2~. Similar risk factors
existed for the outcome of frequent multiple work-related chest
symptoms, which may represent asthma-like conditions for
which medical consultation has not been sought or for which an
asthma diagnosis was not made. Although these findings do not
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ASTHMA AND NONRESIDENTAL INDOOR ENVIRONMENTS 321
document specific agents causing asthma in office buildings, they
suggest that bioaerosols associated with HVAC moisture, mainte-
nance deficiencies, and water damage requiring renovation are
promising hypotheses.
Commercial office building stock and schools are often con-
structed with flat roofs, which predispose to puddling and mois-
ture incursion; other common sources of moisture problems in
nonindustrial building stock are HVAC coils, drain pans, and duct
liners; below-grade drainage; inadequate moisture barriers; flash-
ing leaks; flooding; and plumbing mishaps. At present, little in-
formation is available regarding the relative health risks of these
conditions. Absent risk assessment information, building occu-
pants, tenants, and managers have little leverage to have these
conditions fixed.
STUDIES OF SCHOOLS
School is an important indoor environment for many children.
The possible influence on health of indoor air in schools and day
care centers have been the subject of research. However, very little
of this literature specifically addresses indoor air exposures and
asthma. Of the available studies on the topic, few have done care-
ful and complete exposure assessments.
Schools are subject to many of the same exposure problems
found in homes, although not necessarily at the same levels. The
level of some allergens such as cockroach and dust mite is thought
to be generally lower in schools because of the relative scarcity of
appropriate habitats for infestation (Perzanowski et al., 1999;
Sarpong et al., 1997~. The absence of a direct source does not, how-
ever, necessarily preclude its presence. Cat allergen which clings
to clothing and other belongings has been measured in schools
and other indoor environments where cats have never been
(Chan-Yeung et al., 1999~. Indeed, schools may be a major source
of exposure to cat and dog allergen for individuals who do not
have these pets at home (Almqvist et al., 1999; Lonnkvist et al.,
1999~.
A survey of research on indoor air quality in schools noted
that the major building-related problem identified was inad-
equate outdoor air ventilation (Daisey and Angell, 1998~. Water
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322
CLEARING THE AIR
damage and concomitant mold growth constituted the second
greatest problem.
Among the epidemiologic studies identified by the commit-
tee, Smoke and colleagues (1997) investigated air quality, envi-
ronmental characteristics, and asthma outcomes in 762 students
in 39 schools in Uppsala County, Sweden. They used a self-ad-
ministered questionnaire for health status information and em-
ployed trained occupational hygienists to gather building infor-
mation and measurements in the schools. Data gathered included
air exchange rate, temperature, and relative humidity; airborne
levels of volatile organic compounds (VOCs), NO2, molds, and
bacteria; and levels of endotoxin, and cat, dog and mite allergen
in settled dust. They found that self-reported current asthma was
more common in schools that were larger, and had more open
shelves (a repository of settled dust), lower room temperature,
higher relative humidity, higher concentrations of formaldehyde
or other VOCs, viable mold or bacteria, and more cat allergen.
The observations were drawn on the basis of 40 asthma cases.
Haverinen and colleagues (1999) investigated three school
buildings that were suspected of causing occupant health prob-
lems. The buildings were subjected to extensive structural and
microbial contamination surveys; questionnaires were used to
collect data on health problems. Widespread moisture damage
was observed. Fungi identified (Aspergillus, Eurotium) were typi-
cal of buildings with mold problems. The prevalence of self-iden-
tified asthma among upper secondary school students, but not
elementary or high school students, was reported to be higher
than typical for the age group.
Hunting (1999) noted that half (14 of 28) of the cases of re-
ported "occupational asthma" or RADS from primary and sec-
ondary schools and vocational schools in AOEC's Occupational
and Environmental Disease Surveillance Database over the years
1991-1996 were attributed to indoor air exposures. The specific
exposures were not identified.
Nafsted and colleagues (1999) investigated the respiratory
health of 3,853 children in Oslo, Norway. Parents completed a
questionnaire concerning day care arrangements, the child's
health, environmental conditions, and family characteristics. The
study found that the lifetime risk of doctor-diagnosed asthma was
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ASTHMA AND NONRESIDENTAL INDOOR ENVIRONMENTS 323
higher in children who started attending day care centers during
the first two years of life. The authors speculated that this was a
consequence of the higher rate of early respiratory infections in
children in day care. There were no data reported on other envi-
ronmental exposures.
Two studies addressed respiratory outcomes in children in
the United States. A study of 1,268 children in Minnesota by
Marbury and colleagues (1997) found that day care attendance
was associated with an increased risk of recurrent wheezing ill-
nesses and lower-respiratory infections. Celedon and colleagues
(1999) examined respiratory tract illnesses in 498 Boston-area chil-
dren who had at least one parent with a history of allergy or
asthma. Researchers found that day care attendance increased the
risk of upper and lower respiratory tract illnesses in the first year
of life for these children. (Chapter 5 includes a discussion of the
state of the literature regarding exposure to infectious agents and
asthma.)
Such findings are not, however, uniform. McCutcheon and
Woodward (1996) studied the respiratory health of 445 Adelaide,
South Australia, school children, using data from questionnaires
completed by parents and school records. They found that chil-
dren who had attended child care prior to commencing school
experienced half as many episodes of asthma as children who
had never attended child care. Among the explanations for the
findings offered was protection against later respiratory illness as
a result of early exposure, although selection of ilIness-prone chil-
dren into home care might also have had an influence.
School exposures are an area of continuing research interest.
One ongoing study of schools in the Chicago area is monitoring
levels of a wide variety of potentially problematic agents includ-
ing molds, dust mites, animal and insect allergens, particulates
and various chemicals and other environmental characteristics
such as ventilation and humidity. The study is also evaluating the
effect of interventions including educational initiatives and inte-
grated pest management. An interesting observation from this ef-
fort is the importance of involving engineering and janitorial staff,
along with school management, in the planning and implementa-
tion of interventions (Persky, 1999~.
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324
CLEARING THE AIR
CONCLUSION
Published case reports, public health surveillance of physi-
cian reporting, and cross-sectional studies of building occupants
with indoor air quality complaints provide limited or suggestive
evidence of an association between aspects of the nonindustrial
indoor environment and the development of asthma with a build-
ing occupancy-related pattern of symptoms and, in some in-
stances, objective abnormalities. What is lacking for the most part,
however, is knowledge of specific etiologic agents in these nonin-
dustrial indoor environments that might be responsible for these
new work-related asthma cases. Epidemiologic data suggest that
moisture and ventilation system problems are markers for the
problematic agents when work-related asthma arises in particu-
lar office and school buildings. Similarly, one cross-sectional study
comparing two building populations (with comparable IAQ dis-
comfort complaints) provides evidence that one particular office
environment caused exacerbation of asthma among more than a
third of occupants with preoccupancy physician diagnoses of
asthma, and the other office environment did not. However, the
proportion of building environments that precipitate exacerba-
tion of asthma and the specific etiologies of asthma exacerbation
are unstudied.
RES"RCH NEEDS
The few available studies suggest the importance of building
factors in relation to asthma, but further research is critical to as-
sessing the attributable risks, remediable risk factors, and means
of hazard assessment. Development of methods for representa-
tive quantitative assessment of bioaerosols of fungal and bacte-
rial origin is a high priority for health outcome studies and haz-
ard assessment. In addition, knowledge of the epidemiology of
building-related asthma in problem buildings where there are ex-
cess chest complaints among occupants, in comparison to build-
ings where there are no complaints, can advance our understand-
ing of specific bioaerosols in relation to asthma. Research should
focus on exposure-response studies of many building environ-
ments and populations; clinical investigation of patients with
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ASTHMA AND NONRESIDENTAL INDOOR ENVIRONMENTS 325
building-related asthma; and intervention studies, even without
knowing the specific etiology involved. This research agenda re-
quires new partnerships among academic investigators, clini-
cians, public health agencies, industrial hygienists, and building
scientists.
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Representative terms from entire chapter:
day care
