Children's Health Articles 

Levels of Household Mold Associated with Respiratory Symptoms in the 

First Year of Life in a Cohort at Risk for Asthma 

Janneane 1=. Gent, I Ping Ren,z Kathleen Belanger,I Elizabeth Triche,I Michael B. Bracken, I Theodore R. Holford,~ 

and Brian P. Leadererl 

'Yale Center for Perinatal, Pediatric and Environmental Epidemiology, Department of Epidemiology and Public Health, Yale University 

School of Medicine, New Haven, Connecticut, USA; zNew York State Department of Health, Albany, New York, USA 

We assessed prospectively the risk of increased incidence of respiratory symptoms after exposure 

to particular fungal genera in a susceptible population-namely, infants (n = 880) at high risk for 

developing asthma. Days of wheeze or persistent cough, information on maternal allergy and 

asthma, socioeconomic variables, and housing characteristics were collected over the course of the 

infant's first year of life. Exposure to mold was assessed by airborne samples collected at one time 

early in the infant's life. Fungi were identified to genus level, recorded as colony-forming units per 

cubic meter (CFU/m3), and then categorized into four levels : 0 (undetectable), 1-499 CFU/m3 

(low), 500-999 CFU/m3 (medium), and a 1,000 CFU/m3 (high) . Effects of mold on wheeze and 

persistent cough, adjusting for potential confounding factors, were examined with Poisson regression analyses . The two most commonly found genera were Cladosporium (in 62% of the homes) 

and Penicillium (41%). Cladosporium was associated with reported mold (p < 0.02) and water 

leaks (p < 0.003). Rate of persistent cough was associated with reported mold [Rate ratio (RR) = 

1 .49; 95% Cl, 1.18-1 .88] . The highest level of Penicillium was associated with higher rates of 

wheeze (RR = 2.15; 95% Cl, 1 .34-3.46) and persistent cough (RR = 2.06; 95% Cl, 1 .31-3.24) in 

models controlling for maternal history of asthma and allergy, socioeconomic status, season of 

mold sample, and certain housing characteristics . We conclude that infants in this high-risk group 

who are exposed to high levels of Penicillium are at significant risk for wheeze and persistent 

cough. Key words: asthma, &ungi, indoor air, infants, mold, Penicillium, wheezing. Environ Health 

Perspect 110tA781-A786 (2002) . [Online 12 November 2002] 

http ://ehpnet] .niehs.nih.gov/docs/2002/110pA781-A786gent/ahstract .html 

Fungi are ubiquitous on this planet, and 

exposure to them a fact of life for all residents 

of Earth . There is little doubt that exposure 

to fungi contributes to respiratory diseases 

and their symptoms (Al-Doory and Domson 

1984; Dillon et al . 1999; Husman 1996; 

Larone 1987; Peat et al . 1998; van der Werff 

1958; Verhoeff and Burge 1997) . The effect 

of indoor fungal exposures on the respiratory 

health of children is of particular concern and 

has been examined worldwide . Studies have 

been primarily of children recruited directly 

from schools in Canada (Dales et al . 1999), 

the Netherlands (Verhoeff et al . 1995), 

Sweden (Rylander et al . 1998), and Taiwan 

(Su et al. 20016), or children who were members of surveyed families in Australia (Garrett 

et al . 1998), Israel (Katz et al . 1999), and the 

United Kingdom (Platt et al . 1989) . A few 

studies have specifically examined the effects 

of fungal exposure on children with respiratory or allergic disease (Dill and Niggemann 

1996; Li et al. 1995 ; Su et al . 2001a). 

Several methods are used to assess levels of 

mold exposure, including counting fungal 

spores in airborne samples or quantifying constituents of fungal cells contained in dust samples . Compared to dust sample analyses that 

can quantify cumulative exposure to mold in 

general (e.g ., Chew et al . 2001; Dharmage et 

al . 2001; Douwes et al . 1999), air sampling 

remains the best way to identify genera and 

species of molds found in and around a home 

(Ren et al . 1999) . Relationships between 

exposure to mold and respiratory symptoms 

of children have been explored for airborne 

samples analyzed as total mold spore counts 

(Platt et al . 1989 ; Strachan et al . 1990; 

Waegemaekers et al . 1989), and as concentrations of specific genera (e .g ., Cladosporium, 

Penicillium, Alternaria, Aspergillus) (Garrett et 

al . 1998; Li et al . 1995; Su et al . 2001a) . 

No studies have reported on mold exposures in early life and respiratory symptoms in 

a susceptible population . Since 1998, we have 

been following a birth cohort of 1,002 infants 

at risk for developing asthma. We have 

reported previously on the relationship 

between airborne fungi and characteristics of 

our study subjects' homes (Ren et al . 2001). 

In the present study we examine which specific mold exposures might be related to respiratory symptoms while controlling for 

potentially confounding factors . 

Methods 

Cohort. We studied 1,002 infants born 

to mothers in Connecticut and western 

Massachusetts between September 1996 and 

December 1998, who had at least one older 

child with physician-diagnosed asthma. The 

Human Investigation Committee of Yale 

University approved this study, and all 

respondents gave informed consent before 

participation. 

Because they all had at least one sibling 

with asthma, the infants in this birth cohort 

were considered to be at high risk for developing asthma. Within 4 months of the 

infant's birth, a trained research assistant 

interviewed each mother at home to collect 

demographic information, medical histories, 

and household characteristics . Mothers were 

asked whether the infant had experienced 

wheeze or persistent cough since birth and, if 

so, how many days in each month the symptoms occurred. Infant respiratory symptoms 

were collected at quarterly telephone interviews when the infant was 6, 9, and 12 

months of age. When the infant was 12 

months old, a more extensive questionnaire 

was administered covering additional household characteristics specific to the previous 

year, including the respondent's observation 

of persistent mold or mildew in the living 

area of the home. 

Of the initial 1,002 infants enrolled, 880 

were included; for these, symptom information 

was available for 1 to 12 months in the home 

from which the mold sample was taken. 

Excluded were 39 families who moved at some 

unknown date from the home where the mold 

sample was taken, 54 who were lost to followup, and an additional 29 who were missing 

information on measured mold. Data from 

these 880 infants were used in analyses of general characteristics of the infant and home collected at the time of the home interview. Data 

from a subset of 819 infants whose mothers 

participated in the year 1 questionnaire were 

used for analyses including housing characteristics specific to the infant's first year of life . 

Address correspondence to J .F . Gent, Yale Center for 

Perinatal, Pediatric and Environmental Epidemiology, 

One Church Street, 6th Floor, New Haven, CT 

06510 USA. Telephone: (203) 764-9375 . Fax: (203) 

764-9378. E-mail : janneane.gent@yale .edu 

We thank the 1,002 families who permitted us to 

conduct airborne mold sampling in their homes, and 

the hospitals from which our study population was 

selected : Yale-New Haven, Danbury, Bridgeport, 

and Hartford (CT), and Bay State (MA) . 

This work was supported by grants ES07456 and 

ES05410 from the National Institute of Environmental 

Health Sciences . 

Received 12 April 2002 ; accepted 26 July 2002 . 

Environmental Health Perspectives " VOLUME 110 1 NUMBER 12 1 December 2002 A 781 
Children's Health " Gent et al . 

Collection and analysis of mold samples. 

Sample collection and analysis have been 

described previously (Ren et al . 2001) . Results 

reported here are from airborne mold samples 

collected from the main living area at the time 

of the home visit within 4 months of the 

infant's birth. A Burkard portable air sampler 

(Burkard Manufacturing Co., Rickmansworth, 

UK) was used in combination with dichloran18% glycerol agar (DG-18) . The sampling 

period was 1 min with an airflow rate of 20 

L/min. Fungi were identified to the genus level 

and recorded as colony-forming units (CFU) 

per cubic meter. 

Data analysis. The health outcomes of 

interest were infant respiratory symptoms of 

wheeze and persistent cough measured as 

counts (i .e ., number of days of symptom 

summed over the period of time that the 

infant lived in the home where the mold sample was taken) . Symptom counts were converted to yearly rates by dividing number of 

days of symptoms by the number of days of 

observation and multiplying times 365 days 

per year. For some analyses, yearly rates were 

categorized into three levels previously established for an asthma severity scale (Ortega et al. 

2001): 0 days, < 30 days/year, z 30 days/year . 

The total culturable number of colonyforming units per cubic meterwas categorized 

into four levels according to the Commission 

of European Communities report (CEC 

1994) : 0 (undetectable), 1-499 CFU/m3 

(low), 500-999 CFU/m3 (medium), and a 

1,000 CFU/m3 (high) . Exposure variables of 

interest for further analyses included all 

specifically identified genera of fungi . Total 

amount of yeast, which is not speciated, was 

noted but not included in further analyses . 

Other variables of interest were collected at 

the home interview (n = 880), including personal and socioeconomic information (infant 

sex, ethnicity, maternal history of asthma and 

allergies, mother's education level, multifamily 

home), other housing characteristics (smoking 

in the home, heating system), and season mold 

sample was taken: winter (the months 

of December-February), spring (MarchMay), summer (June-August), and fall 

(September-November) . Additional information on housing characteristics specific to the 

infant's first year of life in the home where airborne mold was sampled were collected at year 

1 interviews (n = 819) and included reports of 

mold and mildew, problems with water leaks, 

and use of humidifiers and/or dehumidifiers. 

Because wheeze and persistent cough data 

are in the form of counts (number of days of 

symptoms), we used Poisson regression analysis 

to examine associations between symptoms and 

mold variables, both unadjusted and adjusted 

for potential confounding factors . Rate ratios 

(RR) and 95% confidence intervals (CI) were 

computed using the GENMOD procedure in 

SAS specifying the Poisson distribution and 

invoking the scaling factor correction for 

overdispersion (SAS 2001). Because not all 

infants were under observation for a full year, 

and to standardize the length of the monitoring period, we added an offset variable (log of 

the number of days during the first year of life 

that the infant was under observation) to the 

model (Allison 1999; SAS 2001) . Models 

were built for the simultaneous effects of 

Penicillium, Cladosporium, and "other" mold, 

using backward elimination of nonsignificant 

confounders, with reinclusion if the confounder's exclusion produced > 10% change in 

the coefficients of the exposure variables . For 

each mold variable, each category of mold 

exposure (low, intermediate, high) was entered 

into the models as a dummy variable with the 

"undetectable" category serving as baseline . 

Results 

Overall, 80% of the infants remained in the 

study home for 1 full year, 12o/o were followed 

for 9-11 months, 5% for 6-8 months, and 

3% for fewer than 6 months. Over half of the 

infants did not experience any wheeze 

(58 .8%) or persistent cough (54.3%) . 

Approximately one-third of the infants who 

experienced symptoms had the equivalent of 

30 or more days of wheeze (27 .5n/o of 402 

infants) or persistent cough (32.8n/o of 363) . 

Table 1 displays the unadjusted relationships between personal, socioeconomic, and 

housing characteristics and the rates of 

wheeze and persistent cough. There is significantly more wheeze and persistent cough 

among boys (xZ, p < 0.04) and among infants 

whose mothers have asthma (p < 0.002). 

Higher rates of wheeze are found among 

Hispanic infants (p < 0.007), infants of mothers with less than a high school education (p < 

0.004), and infants living in multifamily 

housing (p < 0.001) . Infants in homes heated 

with an electric baseboard system tend to 

have higher rates of wheeze than those in 

homes with forced air, steam, or any other 

system (p < 0.01) . Rates of respiratory 

symptoms were not associated with smoking 

Table 1 . Unadjusted associations between personal, socioeconomic, housing characteristics, and respiratory symptoms of 880 infants at risk for developing asthma from Connecticut and western Massachusetts, 

1998-2000. 

Rate of persistent cough Rate of wheeze 

(days/year) (%) (days/year) (%1 

Characteristic No . 0 < 30 Z 30 p-Valuea 0 < 30 z 30 ~rValuea 

Infant's sex 

Male 437 50 .1 34 .1 15 .8 0.04 54.5 31 .8 13 .7 0.02 

Female 443 58 .5 27 .3 14 .2 63.0 28 .0 9.0 

Ethnicity 

White, Asian, other 554 54 .7 31 .8 13 .5 0.08 61 .4 30 .1 8.5 0.007 

Black 120 60 .0 28 .3 11 .7 57 .5 29 .2 13 .3 

Hispanic 206 50 .0 29 .1 20.9 52 .4 29 .6 18 .0 

Mother has diagnosed asthma 

No 601 58 .6 29 .1 12.3 0 .001 62 .6 28 .0 9 .5 0 002 

Yes 279 45 .2 34 .0 20.8 50 .5 34 .0 15 .4 

Mother has allergies 

No 371 57 .4 28 .3 14.3 0.28 61 .2 29 .9 8 .9 0.13 

Yes 509 52 .1 32 .4 15.5 57 .0 29 .9 13 .2 

Mother's education (years) 

< 12 125 54 .4 24 .6 20.0 0.34 50 .4 28 .8 208 0 .004 

12-15 463 53 .8 31 .1 15.1 59 .4 29 .4 11 .2 

> 15 292 55 .1 32 .9 127 61 .3 31 .2 7 .5 

Multifamily home 

No 716 54 .6 31 .3 14.1 0.28 60 .5 30 .0 9.5 0.001 

Yes 164 530 28 .0 18.9 51 .2 29 .3 19 .5 

Smoking in the home 

No 761 53 .2 31 .1 15.6 0 .20 59 .3 29 .7 11 .0 0.65 

Yes 119 613 27 .7 10.9 55 .5 31 .1 13 .4 

Heating system 

Forced air 309 58 .2 25 .6 16.2 0 .18 61 .5 28 .8 9.7 0.01 

Steam/hot water 419 51 .3 33 .9 14.8 59 .0 30 .8 10 .3 

Electric 123 55 .1 30 .9 13 .0 53 .7 26 .0 20 .3 

Other 24 41 .7 45 .8 12 .5 45 .8 50 .0 4.2 

Water leaksb 

No 636 56 .0 29 .7 14.3 0 .10 60 .4 30 .0 9.6 0.45 

Yes 183 47 .0 36 .6 16 .4 55 .2 339 10 .9 

Humidifier useb 

No 377 56 .8 31 .0 12 .2 0 .12 60 .2 31 .8 8.0 0.23 

Yes 442 51 .6 31 .4 17 .0 58 .4 30 .1 11 .5 

Dehumidifier useb 

No 597 52.3 31 .7 16 .1 0 .15 57 .3 31 .7 11 .1 0.09 

Yes 222 58.6 30.2 11 .3 64 .4 28.8 6.8 

'p-Values for xz tests. 'Data from questionnaire administered at the infant's first birthday (n= 8191 . 

A 782 VOLUME 110 1 NUMBER 12 1 December 2002 " Environmental Health Perspectives 
Children's Health " Airborne mold and infants at risk f or asthma 

in the home, mother's history of allergies, 

reported water leaks in the home, or the use 

of a humidifier or dehumidifier . 

Genera of mold identified in the 

main living room of 880 homes included 

Cladosporium (found in 61 .9% of the homes) 

and Penicillium (in 40 .6%) . Although 

Aspergillus (in 25.6%) and Alternaria (12 .1%) 

were also quite common, neither was found 

in sufficient numbers to be analyzed separately. An additional 21 genera were identified including Wallemia (7 .5%), Epicoccum 

(5 .9%), Botrytis (3 .1%), and others found in 

less than 3% of the homes. No mold could be 

detected in the main living room of 15 .6% of 

the homes. The number of different genera 

per sample in the remaining samples ranged 

from 1 to 7 (median = 2 different molds) . 

Cladosporium was the only mold identified in 

11 .7% of the samples while Penicillium was 

the only mold in 7 .8%. Both were present 

in 27 .3% of the main room samples . 

Unspecified yeast was found in 44.2% of the 

samples, and it was not possible to identify at 

least one of the molds present on 24.4% of 

the samples . 

Table 2 displays bivariate associations 

between season of mold sampling, housing 

characteristics, and measured mold. There is 

no association between season of sampling 

and level of Penicillium. There is a significant 

association between season and level of 

Cladosporium and "other" mold (p < 0.0001) . 

Only Cladosporium is associated with the 

mother's observation of mold (p < 0.02) or 

water leaks (p < 0.003) during the first year of 

the infant's life. Higher levels of "other" mold 

were associated with steam/hot water home 

heating systems (p < 0.05) . 

For the infants who experienced respiratory 

symptoms, Figure 1 shows the frequency distributions for days of wheeze and persistent cough 

in the first year of life (expressed as the rate 

multiplied by 365 days) over each level of 

Penicillium and Cladosporitsm . An examination 

of the tail of the distribution for days of wheeze 

in the presence of Penicillium reveals that 

although only 19 of 363 infants were exposed 

to high levels of this mold, 37% of them experienced 60 or more days of wheeze in their first 

year of life (Figure 1 B) . Interestingly, only 3% 

of 29 infants exposed to high levels of 

Cladasporium had this same high rate of wheeze 

(Figure 1D). The distribution for days of persistent cough shows a similar pattern in the 

tails: More infants experience 60 or more days 

of persistent cough in the presence of high levels of Penicillium (5 of 18, or 28%) (Figure lA) 

than do in the presence of high levels of 

Cladosporium (0 of 31) (Figure 1 C). 

Table 3 shows the unadjusted associations resulting from a Poisson regression 

analysis between the rates of respiratory 

symptoms and exposure to particular levels 

of molds. As illustrated in Figure 1, high 

levels of Penicilliuns are significantly associated with wheeze (RR = 2 .46 ; 95% CI, 

1 .63-3 .70) and persistent cough (RR = 1 .84 ; 

95% CI, 1 .22-2 .80) . In addition, persistent 

cough is also significantly associated with the 

medium level of Cladosporium (RR = 1 .62 ; 

95% C1, 1 .17-2 .24) and with mother's 

report of mold in the home (RR = 1 .49 ; 

95% CI, 1 .18-1 .88) . 

The simultaneous effects of Penicillium, 

Cladosporium, and "other" mold adjusted for 

potential confounding factors are displayed in 

the Poisson regression models in Table 4. The 

presence of Penicillium appears to increase the 

chances that an infant will experience significant 

respiratory symptoms during the first year of 

life. The model for rate of persistent cough suggests that when controlling for maternal history 

of asthma, mother's education level, season of 

mold sample, water leaks, humidifier or dehumidifier use, and smoking in the home, an 

infant's number of days of persistent cough during the first year of life in the presence of a high 

level of Penicillium would be double the number experienced in the presence of undetectable 

levels of this mold (RR 2.06 ; 95% CI, 

1 .31-3 .24) . It appears that when controlling for 

confounding factors and level of Penicillium, 

neither Clndosporium nor "other" mold affects 

respiratory symptoms experienced by an infant 

during the first year of life . 

Similarly, the model for rate of wheeze 

suggests that when controlling for the factors 

mentioned above plus the infant's sex, maternal history of allergies, multifamily home, 

and home heating system, an infant's number 

of days of wheeze in the first year of life in the 

presence of high levels of Penicillium would 

again be double the number experienced 

when unexposed to Penicillium (RR = 2.15 ; 

95% CI, 1 .34-3 .46) . 

Ethnicity and use of air conditioners were 

included in initial models predicting rates of 

wheeze and persistent cough, but were eliminated because they had no confounding 

effects on the remaining variables (i .e ., > 10% 

change in the parameter estimate of interest) . 

Discussion 

We assessed the risk of increased incidence of 

respiratory symptoms as a result of exposure to 

particular fungi in a susceptible populationTable 2 . Unadjusted associations between season of sampling, housing characteristics, and mold measured in 880 homes 2-4 months after an infant's birth 

(Connecticut and western Massachusetts, 1998-2000) . 

Variable No . 0 

PenicilliurrP (°/al 

Low Med High p-Value 

Season mold sample taken 

Winter 181 66.8 26 .5 

Spring 244 59 .8 33 .6 

Summer 219 56 .6 37 .4 

Fall 236 55 .9 37 .3 

Heating system 

Forced air 309 61 .8 32 .0 

Steam/hot water 419 57 .0 35.8 

Electric 123 61 .0 33 .3 

Other 24 58 .3 37 .5 

Reported mold' 

No 644 60 .9 33.5 

Yes 174 54 .0 37.4 

Water leaks' 

No 636 59 .3 34.1 

Yes 183 59 .6 35.5 

Humidifier use' 

No 377 57 .8 34.5 

Yes 442 60 .6 34 .4 

Dehumidifier use' 

No 597 59.1 35 .0 

Yes 222 59.9 32 .9 

0 

CladosporiurW (%) 

Low Med High p-Value 

1 .7 5.0 0.51 71 .3 27 .1 1 .7 0.0 

2.5 4.1 57 .0 377 2.9 2.5 

2.7 3.2 12 .3 48 .2 21 .9 17 .4 

2.5 4.2 17 .0 63 .1 12 .7 7.2 

2.9 3.2 0.85 41 .0 44 .0 8.7 6.2 

2.6 4.5 36.8 44 .2 11 .9 7.2 

0.8 4.9 33.3 50 .4 8 .1 8.1 

0.0 4.2 50 .0 41 .7 0.0 8.3 

2.2 3.4 0.30 38 .8 46 .3 9.3 5.6 

3.4 5.2 35 .1 40.8 12 .6 11 .5 

2.7 3.9 0 .83 37 .9 46.9 8.0 7.2 

1 .6 3.3 38 .2 39.3 16 .9 5.5 

2.4 5,3 0.21 38 .5 45,1 10 .6 5.8 

2.5 2.5 37 .6 452 9.5 7.7 

2.8 3.0 0.16 37 .4 46 .4 10 .6 5.7 

1 .4 5.9 39 .6 41 .9 8.6 9.9 

Other mold,' (%) 

0 Low Med High p-Value° 

0.0001 61 .3 33 .7 1 .1 3 9 0.0001 

49.6 48 .4 1 .6 0.4 

26 .5 63 .0 7 .3 3 .2 

32 .3 57 .2 7 .2 3 .4 

0.43 46.6 45 .6 6 .2 1 .6 0.05 

40 .8 52 .0 3 .3 3.8 

32 .5 61 .8 4.1 1 .6 

37 .5 58 .3 4.2 0.0 

0.02 42 .7 50 .8 4.0 2.5 0.42 

36 .8 54.0 5.8 3.4 

0.003 42 .3 50.9 4.4 2.4 0.64 

388 53 .0 4.4 3.8 

0.72 41 .9 51 .5 3.4 3 .2 0.55 

41 .2 51 .4 5 .2 2 .3 

0.12 41 .2 52 .4 4 .0 2.4 0.54 

42 .3 48 .6 5 .4 3.6 

'Undetectable : 0; low: 1-499 CFU/m3 ; medium : 500-999 CFU/m3; high : z 1,000 CFU/m3. bp-Values for X2 tests. 'Data from questionnaire administered at the infant's first birthday (n=819) . Environmental Health Perspectives " VOLUME 110 1 NUMBER 12 1 December 2002 A 783 
Children's Health " Gent et al . 

namely, infants at high risk for developing 

asthma. Our assessment also considers factors 

that might have confounding effects, such as 

maternal allergy and asthma, socioeconomic 

variables, and housing characteristics . We conclude that infants in this high-risk group who 

are exposed to higher levels of Penicidium are at 

significant risk for wheeze and persistent cough. 

Previous studies suggest that the relationship between exposure to mold and respiratory symptoms of children is complicated and 

may depend on risk level of the study population, health outcomes measured, exposure 

assessment methodology, and other factors 

identified as potentially confounding. Results 

of previous studies examining respiratory 

symptoms of children and indoor exposure to 

measured airborne mold as represented by 

total mold spore count are equivocal . Platt et 

al . (1989) used airborne mold sampling to 

confirm observed mold and found that children living in homes classified as damp and 

moldy had significantly more respiratory 

symptoms than did children in dry homes. In 

a study of 88 7-year-olds from a population 

survey of 1,000 homes in the United 

Kingdom, Strachan et al . (1990) used measured mold as the exposure variable and 

concluded that inhaled mold spores (total 

mold count) is not an important factor 

in causing wheeze. On the other hand, 

Waegemaekers et al . (1989) studied 190 

school-aged children in the Netherlands and 

501 A 

40 

30 

e 

m 

0 

P 20 

10 

B 

Persistent cough/Penicillium 

111 .11.4.1 .n 

for a subset of 56 children reported an association between the presence of exposure to mold 

(modeled as the loglo of total mold count in 

CFU/m3) and persistent cough [odds ratio 

(OR) = 1 .98 ; p < 0.051 and a combination of 

wheeze and persistent cough (OR = 1 .93; p < 

0.05), adjusted for socioeconomic variables 

and household characteristics. 

Results of studies examining the relationship between exposure to specific mold genera 

and respiratory symptoms have also been 

equivocal . Garrett et al. (1998) took repeated 

airborne samples from 80 homes of 148 7-14-

year-olds and concluded that an increase in 

winter exposure to Penicillium by 100 

CFU/m3 (OR = 1 .43 ; 95% CI, 1 .03-2 .00), 

Table 3 . Unadjusted associations estimated as RRs and 95a/a Cls between measured mold, reported mold, 

and respiratory symptoms of 880 infants (Connecticut and western Massachusetts, 1998-2000) . 

Factor No . 

Measured molda 

Penicillium 

Undetectable (R) 52 

Low 300 

Medium 21 

High 36 

Cladosporium 

Undetectable (R) 335 

Low 396 

Medium 88 

High 61 

"Other" mold' 

Undetectable (R) 339 

Low 421 

Medium 36 

High 22 

Reported moldc 

No (R) 644 

Yes 174 

Persistent cough Wheeze 

RR (95% CI) RR (95% CI) 

1 .07 (0.86-1 .34) 1 .06 (0 .82-1 .36) 

1 .67 (0 .96-2.93) 1 .10 (0 .51-2.34) 

1 .84 (1 .22-2.80)* 2.46 (1 .63-3.70)* 

1 .17 (0 .92-1 .47) 1 .12 (0 .87-1 .45) 

1 .62 (1 .17-2.24)* 1 .07 (0 .71-1 .61) 

0.75 (0 .45-1 .24) 0.83 (0 .50-1 .40) 

1 .24 (1 .00-1 .54) 1 .31 (1 .00-1 .63) 

0 .78 (0 .42-1 .45) 1 .13 (0 .63-2 .03) 

1 .14 (0 .60-2.16) 0 .88 (0 .39-1 .98) 

1 .49 (1 .18-1.88)* 1 .23 (0.94-1 .61) 

R, reference category. 

'Undetectable : 0 CFU/m3; low: 1-499 CFU/m3; medium : 500-999 CFU/m3; high : z 1,000 CFU/m3. d"Other" mold defined as 

total spore counts minus counts for Penicillium, Cladosporium, and yeast. Tata from questionnaire administered at the 

infant's first birthday (n = 819) . *p< 0.05 . 

40 

a 

30 

e 

m 

0 

c 

;! 20 

10 

0 1-9 10-- 20- 6 8 

30- 

40- 50- 60- 

70- 

80- 

9 29 39 49 59 9 79 9 

5 0 

40 

0 

a 

c 

N 

30 

20 

10 

0 

© 

1-9 10-

19 

90- 100-1~0-~20-~30-140- 150-160-170->180 

99 109 19 29 39 149 159 69 179 

Persistent coughJCladosporium 

-1 A - 

20- 30- 40- 50- 60-70- 80- 98-188-110-120-130-140- 150-168- 170- > 180 

29 39 49 59 69 79 89 99 109 119 129 139 149 159 169 179 

10 

0 

WheezelPenicillium 

Exposure category (n) 

0 0(210) 

" Low (125) 

" Medium (9) 

" High (19) 

1-9 1(~-20- 30-40-50- 60-713-80 AL - - 90-100-~10-120-130-~40-150-160-17V>180 

19 29 39 49 59 69 79 89 99 109 9 129 139 49 159 169 179 

1-9 10- 20- 30- 40- 50- 60- 70- 80- 90- 100- 110- 120- 130- 140- 150- 16(- 170- > 180 

19 29 39 49 59 69 79 89 99 109 119 129 139 149 159 169 179 

Figure 1 . Rate of respiratory symptoms per year for infants who experienced any persistent cough (45.7%) (A,C) or wheeze (41.2% of 880) (BD) in the first year of 

life . Because not all infants were followed for a full year, respiratory symptom rates, expressed as number of days of symptoms per days of follow-up, were multiplied by 365 days to produce a rate per year . Distribution of symptoms is shown for each exposure category of Penicillium (A,8) and Cladosporium (CD) . Data 

from Connecticut and western Massachusetts, 1998-2000. 

Exposure category (n) 

0 0(149) 

" Low (174) 

" Medium (48) 

" High (31) 

50 

e 

40 

30 

y 20 

Exposure category (n) 

0 0(229) 

" Low (144) 

" Medium (11) 

" High (18) 

50 B 

WheezelCladosporium Exposure category (n) 

0 0 (134) 

" Low(157) 

" Medium(43) 

" High (29) 

iu .rA 784 VOLUME 110 1 NUMBER 12 1 December 2002 " Environmental Health Perspectives 
Children's Health " Airborne mold and infants at risk for asthma 

adjusted for parental asthma and allergy, was 

related to asthma. Two studies compared the 

concentration of specific genera of airborne 

mold in the homes of children similar in age 

with and without asthma. One found significant differences in the concentration distributions of Cladosporium and Penicillium 

between disease and control groups (Li et al. 

1995), and the other found no consistent pattern between groups for the various genera of 

fungi (Su et al. 2001a) . 

Interestingly, and consistent with our 

study findings that mold and water leaks are 

significantly associated with Cladosporium but 

not Penicillium, Garrett et al . (1998) also 

found that visible mold and evidence of condensation problems were associated with high 

concentrations of Clndosporium. 

A major strength of our study is that we 

collected extensive respiratory symptom data, 

maternal asthma and allergy histories, and 

housing characteristic information on a large 

population at high risk for developing 

asthma. Another strength is that we were able 

to examine associations between respiratory 

symptoms and exposure to two of the most 

common types of mold through the use of 

airborne mold sampling, which remains the 

best way to identify specific genera . 

Limitations of our study come primarily 

from our mold sampling methodology. Our 

combination of air sampler and agar are considered to produce the best results in terms of 

precision, yield, and number of species isolated (Verhoeff et al . 1990) . But, as with any 

air sampling method, spores from molds that 

are rare or that are not easily airborne will 

result in missed fungal identifications, as will 

spores that grow with difficulty or not at all 

in the chosen medium. Despite this, we feel 

Table 4. Estimates of RRs and 95% Cls from Poisson regression models for measured mold related to 

wheeze and persistent cough in the first year of life adjusted for socioeconomic factors and housing characteristicsa (Connecticut and western Massachusetts, 1998-2000) . 

Factor 

Measured moldb 

Penicillium 

Undetectable (R) 

Low 

Medium 

High 

Cladosporium 

Undetectable (R) 

Low 

Medium 

High 

"Other" mold' 

Undetectable (R) 

Low 

Medium 

High 

Season of mold sample 

Summer (R) 

Fall 

Winter 

Spring 

Water leaks 

Humidifier use 

Dehumidifier use 

Mother has asthma 

Mother's education level (years) 

<12 

12-15 

> 15 (R) 

Smoking in the home 

Heating system 

Forced air (R) 

Steam/hot water 

Electric 

Other 

Male infant 

Mother has allergies 

Multifamily home 

Model for persistent cough Model for wheeze 

RR (95% CI) RR (95% CI) 

1 .01 (0.80-1.28) 1 .11 (0 .87-1 .42) 

1 .62 (0 .93-2.82) 1 .29 (0 .65-1 .48) 

2.06 (1 .31-324)* 2.15 (1 .34-3.46)* 

1 .03 (0,79-1,35) 0.92 (0 .69-1 .22) 

1 .45 (0 .99-2.12) 0.95 (0 .61-1 .49) 

0.72 (0 .42-1 .24) 0.91 (0 .53-1 .56) 

1 .05 (0 .83-1 .33) 0 .97 (0 .75-1 .26) 

0 .78 (0 .42-1 .45) 0.91 (0 .49-1 .68) 

1 .18 (0 .63-2 .21) 1 .02 (0 .49-2 .11) 

0.85 (0 .64-1 .13) 1 .00 (0 73-138) 

0.75 (0 .54-1 .02) 0.87 (0 .59-1 .29) 

0.74 (0 .53-1 .08) 0.81 (0 .57-1 .15) 

1 .17 (0 .91-1 .49) 1 .18 (0 .90-1 .55) 

1 .26 (1 .01-1 .56)* 1 .41 (1 .11-1 .79)* 

0.80 (0 .61-1 .04) 0.83 (0 .61-1 .13) 

1 .49 (1 .20-1 .85)* 1 .40 (1 .10-1 .78)* 

1 .33 (0 .92-1.91) 1 .87 (1 .25-2.80)* 

1 .06 (0 .83-1.36) 1 .20 (0 .90-1 .60) 

0.75 (0 .53-1.08) 0.88 (0 .62-1 .25) 

0.89 (0 .68-1 .15) 

1 .30 (0.93-1 .82) 

0.43 (0.15-1,19) 

1 .60 (1 .26-2.02)* 

1 .23 (0 .97-1.58) 

1 .50 (1 .10-2.02)* 

R, reference category . 

'Outcome data were entered into the model as the number of days of symptoms relative to the number of days the infant 

was under observation . Two additional variables (ethnicity and use of air conditioners) were included in initial models 

predicting rates of wheeze and persistent cough, but both were eliminated and neither had confounding effects on the 

remaining variables . bllndetectable : 0; low : 1-499 CFU/m3; medium : 500-999 CFU/m3; high : 2 1,000 CFU/m3. ""Other" mold 

defined as total spore count minus counts for Penicillium, Cladosporium, and yeast. *p < 0 .05. 

that our method accurately reflects the variety 

of molds present in the homes of our study 

subjects. 

A more serious limitation is that a single 

airborne sample is used to represent mold 

exposure during the first year of life. Airborne 

mold samples, used in many studies as the 

measure of exposure, are quite variable over 

time [e .g., seasonal variation (Beaumont et al. 

1984 ; Gravesen 1972 ; Ren et al . 1999)] and 

space [i.e ., indoors vs . outdoors (Beaumont et 

al . 1984) or between locations indoors, e.g ., 

basements vs. living rooms (Ren et al. 1999)] 

and as such have drawn criticism when used to 

represent longer-term levels of exposure 

(Verhoeff and Burge 1997). Estimates of 

cumulative exposure to mold from a single 

point-in-time sample are provided by dust 

sample analyses of ergosterol (Dharmage et al . 

2001) or extracellular polysaccharide (Chew et 

al . 2001 ; Douwes et al . 1999) . However, 

results of dust sample analyses are relatively 

nonspecific because they involve quantification 

of the aggregate fungal biomass of any molds. 

All of the mold samples used in this 

report were taken from the main living room 

of the home, but were not all collected at the 

same time of year . Roughly one-fourth were 

taken in each season (21n/o winter, 25% summer, 27% fall, 28% spring), and there were 

no significant seasonal differences in the distribution of Penicillium levels (Ren et al . 

1999; Table 3) . Furthermore, a year-long 

study of repeated mold sampling in 11 homes 

in the same geographic area as our study 

(southern New England) demonstrated no 

significant variation in the concentration of 

total fungi in the living room between spring, 

summer, and fall, or between winter, spring, 

and fall, and very little seasonal variation in 

Penicillium as a percentage of total mold concentration (Ren et al . 1999) . Thus, the concentration of Penicillium taken at one time is 

likely to be representative of Penicillium levels 

in the living room of a home in this area 

throughout the year . In contrast, the highest 

values of Cladosporium from the main living 

area in our study are from the summer samples (a time of year when Cladosporium 

reaches its peak levels outdoors) and lowest 

from the winter (Table 3) ; hence the importance of including season of sampling as a 

confounding factor in the models. 

To the extent that our levels of measured 

mold sampled on one occasion represent 

longer-term exposure concentrations, it appears 

that risk of higher rates of respiratory symptoms increases with levels of Penicillium (Table 

4) . This linear trend proved to be significant 

when level of Penicillium was entered into the 

adjusted models as a quasi-continuous variable for both wheeze (RR = 1 .23; 95% Cl, 

1 .0Cr1 .42) and persistent cough (RR = 1 .21 ; 

95% Cl, 1 .0Cr1 .38) . This result implies that 

Environmental Health Perspectives " VOLUME 110 1 NUMBER 12 ]December 2002 A 785 
Children's Health " Gent et al . 

an infant's number of days of respiratory 

symptoms during the first year of life would 

increase by 20n/o for each increase in the level 

of Penicillium (i .e ., from no mold to a low 

level, or from low to intermediate, or from 

intermediate to high) . It also appears that, 

when controlling for potential confounding 

factors including season the mold sample was 

taken, the association between respiratory 

symptoms and mold exposure holds true for 

Penicillium but not for Cladosporium or 

"other" mold. That there are significant seasonal variations in some molds suggests that 

exposure to Cladosporizcm is intermittent and 

may contribute only intermittently to 

respiratory symptoms and not as much as 

Penicillium, which appears to be present at 

more consistent levels year round. 

REFERENCES 

AI-Doory Y, Domson JF . 1984. Mould Allergy . Philadelphia:Lea 

& Febiger. 

Allison PD . 1999 . Logistic regression using the SAS system: 

theory and application . Cary, NC :SAS Institute Inc . 

Beaumont F, Kauffman HF, Sluiter HJ, de Vries K . 1984 . A volumetric-aerobiologic study of seasonal fungus prevalence 

inside and outside dwellings of asthmatic patients living in 

northeast Netherlands. Ann Allergy 53:486-492. 

Chew GL, Douwes J, Doekes G, Higgins KM, van Strien R, 

Spithoven J, et al . 2001 . Fungal extracellular polysaccharides, p(1-3)-glucans and culturable fungi in repeated 

sampling of house dust Indoor Air 11 :171-178. 

CEC. 1994 . Biological Particles in Indoor Environments. Report 

no . 12 . Luxembourg : Commission of the European 

Communities . 

Dales RE, Miller D, White J . 1999 . Testing the association 

between residential fungus and health using ergosterol 

measures and cough recordings . Mycopathologia 

147 :21-27. 

Dharmage S, Bailey M, Raven J, Mitakakis T, Cheng A, Guest 

D, et al . 2001 . Current indoor allergen levels of fungi and 

cats, but not house dust mites, influence allergy and 

asthma in adults with high dust mite exposure . Am J 

Respir Crit Care Mad 164 :65-71 . 

Dill I, Niggemann B . 1996. Domestic fungal viable propagules 

and sensitization in children with IgE mediated allergic 

diseases. Pediatr Allergy Immunol 7:151-155. 

Dillon HK, Miller JD, Sorenson WG, Douwes J, Jacobs RR . 

1999 . Review of methods applicable to the assessment of 

mold exposure to children . Environ Health Perspect 

107(suppl 3):473-480. 

Douwes J, van der Sluis B, Doekes G, van Leusden F, Wijnands 

L, van Strien R, et al. 1999. Fungal extracellular polysaccharides in house dust as a marker for exposure to fungi : relations with culturable fungi, reported home dampness, and 

respiratory symptoms. J Allergy Clin Immunol 103:494-500. 

Garrett MH, Rayment PR, Hooper MA, Abramson MJ, Hooper 

BM. 1998. Indoor airborne fungal spores, house dampness 

and associations with environmental factors and respiratory health in children . Clin Exp Allergy 28:459-467. 

Gravesen S . 1972. Identification and quantitation of indoor airborne micro-fungi during 12 months from 44 Danish 

homes . Acta Allergol 27 :337-354. 

Husman T. 1996 . Health effects of indoor-air microorganisms. 

Scand J Work Environ Health 22:rr13 . 

Katz Y, Verleger H, Barr J, Rachmiel M, Kiviti S, Kuttin ES . 1999. 

Indoor survey of moulds and prevalence of mould atopy in 

Israel . Clin Exp Allergy 29 :186-192 . 

Larone DH . 1987 . Medically Important Fungi : A Guide to 

Identification . 2nd ad . New York:Elsevier. 

Li C-S, Hsu L-Y, Chou C-C, Hsieh K-H . 1995 . Fungus allergens 

inside and outside the residences of atopic and control 

children . Arch Environ Health 50 :38-43. 

Ortega AN, Belanger KD, Bracken MB, Leaderer BP. 2001 . A 

childhood asthma severity scale: symptoms, medications, 

and health care visits . Ann Allergy Asthma Immunol 

86:405-413. 

Peat JK, Dickerson J, Li J . 1998 . Effects of damp and mould in 

the home on respiratory health : a review of the literature . 

Allergy 53:120-128. 

Platt SD, Martin CJ, Hunt SM, Lewis CW. 1989. Damp housing, 

mould growth, and symptomatic health state. Br Mad J 

298:1673-1678 . 

Ran P, Jankun TM, Belanger K, Bracken MB, Leaderer BP . 

2001 . The relation between fungal propagules in indoor air 

and home characteristics . Allergy 56 :419-424. 

Ran P, Jankun TM, Leaderer BP . 1999 . Comparisons of seasonal fungal prevalence in indoor and outdoor air and in 

house dusts of dwellings in one northeast American 

county. J Expa Anal Environ Epidemiol9 :560-568 . 

Rylander R, Norrhall M, Engdahl U, Tunsater A, Halt PG . 1998. 

Airways inflammation, atopy, and (1-3)-(l-D-glucan 

exposures in two schools . Am J Respir Crit Care Mad 

158:1685-1687. 

SAS. 2001 . Version 8. Cary, NC :SAS Institute Inc. 

Strachan DP, Flannigan B, McCabe EM, McGarry F. 1990 . 

Quantification of airborne moulds in the homes of children 

with and without wheeze. Thorax 45:382-387 . 

Su H-J, Wu P-C, Chen H-L, Lee F-C, Lin L-L. 2001a . Exposure 

assessment of indoor allergens, endotoxin, and airborne 

fungi for homes in southern Taiwan . Environ Res 

85:135-144. 

Su H-J J, Wu P-C, Lin C-Y . 2001b. Fungal exposure of children 

at homes and schools : a health perspective. Arch Environ 

Health 56 :144-149 . 

van der Werff PJ . 1958 . Mould Fungi and Bronchial Asthma : A 

Mycological and Clinical Study. Springfield, ILCharles C 

Thomas. 

Verhoeff AP, Burge HA . 1997 . Health risk assessment of fungi 

in home environments . Ann Allergy Asthma Immunol 

78 :544-554 . 

Verhoeff AP, van Strien RT, van Wijnen JH, Brunekreef B. 1995. 

Damp housing and childhood respiratory symptoms : the 

role of sensitization to dust mites and molds . Am J 

Epidemiol 141 :103-110. 

Verhoeff AP, van Wijnen JH, Boleij JS, Brunekreef B, van 

Reenen-Hoekstra ES, Samson RA . 1990. Enumeration and 

identification of airborne viable mould propagules in 

houses : a field comaprison of selected techniques . 

Allergy 45:275-284 . 

Waegemaekers M, van Wageningen N, Brunekreef B, Boleij 

JSM . 1989 . Respiratory symptoms in damp homes . Allergy 

44:192-198. 

nowledge 

A 786 VOLUME 110 1 NUMBER 12 1 December 2002 " Environmental Health Perspectives