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A Prospective Study of Health Symptoms
And Aspergillus fumigatus Spore Counts
Near a Grass and Leaf Composting
Facility
Marilyn L. Brownea, Carole L. Jua, Gregg M. Recera, Lee R.
Kallenbachb, James M. Meliusc & Edward G. Horna
a New York State Department of Health, Center for Environmental
Health, Albany, New York
b Wayne State University, Department of Community Medicine,
Detroit, Michigan
c New York State Laborers' Health and Safety Trust Fund, Albany,
New York
Published online: 23 Jul 2013.
To cite this article: Marilyn L. Browne, Carole L. Ju, Gregg M. Recer, Lee R. Kallenbach, James M.
Melius & Edward G. Horn (2001) A Prospective Study of Health Symptoms And Aspergillus fumigatus
Spore Counts Near a Grass and Leaf Composting Facility, Compost Science & Utilization, 9:3, 241-249,
DOI: 10.1080/1065657X.2001.10702041
To link to this article: http://dx.doi.org/10.1080/1065657X.2001.10702041
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Compost Science & Utilization, (2001), Vol. 9, No. 3, 241-249
A Prospective Study of Health Symptoms
And Aspergillus fumigatus Spore Counts
Near a Grass and Leaf Composting Facility
Marilyn L. Browne1, Carole L. Ju1, Gregg M. Recer1, Lee R. Kallenbach2,
James M. Melius3 and Edward G. Horn1
1. New York State Department of Health, Center for Environmental Health,
Albany, New York
2. Wayne State University, Department of Community Medicine, Detroit, Michigan
3. New York State Laborers’ Health and Safety Trust Fund, Albany, New York
Aspergillus fumigatus (A. fumigatus), a fungus found in compost, is a respiratory aller-
gen and can cause serious invasive disease in susceptible individuals. We conducted
a study involving the collection of health symptom data and environmental monitor-
ing data near a 40-acre grass and leaf composting facility. Analyses were based on
symptom diary data from 63 individuals from the study area and 82 individuals from
a reference area. Airborne A. fumigatus was not associated with increases in respirato-
ry or irritative symptoms. Symptom incidence was associated with ragweed, ozone,
temperature, and time since start of the study, although a tendency to report fewer
symptoms as the study progressed may have confounded this result. Other features
of the study design, including short-term spore count variability, lack of individual ex-
posure data and gaps in the symptom diary data, complicated interpretation of the re-
sults. Although this study does not support an association between allergy and asth-
ma symptom incidence and A. fumigatus spore levels, we could not assess the risk of
unusual, but severe illnesses among very sensitive individuals.
Introduction
With continuing efforts to reduce the landfilling of solid waste and increase recy-
cling, there has been a growth in composting of leaves, brush and grass clippings. The
finished compost product is used for soil conditioning and landscaping purposes. En-
vironmental conditions inside compost piles (heat and humidity) favor the growth of
certain fungi and bacteria able to tolerate high temperatures. One type of fungus found
in compost, Aspergillus fumigatus (A. fumigatus), has generated concern because of po-
tential health effects associated with exposure. A. fumigatus is an allergen and can cause
allergy and asthma symptoms among sensitive individuals (Kwong-Chung and Ben-
net 1992). Other, less common, health effects associated with A. fumigatus include al-
lergic bronchopulmonary aspergillosis (ABPA), aspergilloma and invasive aspergillo-
sis (Marsh et al. 1979; Kwong-Chung and Bennet 1992). More generally, inhaled fungal
spores, including spores of A. fumigatus, can elicit a variety of inflammatory respons-
es in the lung that result from both specific immune responses and non-specific re-
sponses to cellular components such as (1,3)-ꢀ-D-glucans (Weber et al. 1993; Heederik
and Smid 1994; Flannigan and Miller 1994; Rylander 1994) and extracellular polysac-
charides (Douwes et al. 1999).
Facilities that compost yard trimmings (e.g., grass clippings, chipped brush and
wood, leaves) are sometimes located near residential areas. Little is known, however,
about the potential for these facilities to affect the health of nearby residents. Residents
of a town on Long Island, New York became concerned that operations at a 40-acre
grass and leaf composting facility were resulting in health symptoms, particularly res-
piratory symptoms and skin rashes. The New York State Department of Health, the
Compost Science & Utilization
Summer 2001 241

Marilyn L. Browne, Carole L. Ju, Gregg M. Recer, Lee R. Kallenbach,
James M. Melius and Edward G. Horn
New York State Department of Environmental Conservation, the Suffolk County De-
partment of Health Services, the New York State Biological Survey and the Town of Is-
lip undertook a two-part cooperative study to address their concerns. The study in-
volved two components: environmental monitoring and human symptom diaries.
The environmental monitoring study examined whether A. fumigatus spore con-
centrations or those of other bioaerosols in the neighborhood nearest to the facility
(study neighborhood) were being influenced by composting operations. Extensive en-
vironmental data, collected by continuous air sampling over a period of 102 days
(Syzdek and Haines 1995; Recer et al., 2001), showed that higher A. fumigatus spore con-
centrations occurred at the study neighborhood sampling location as compared to the
reference locations. The elevations in A. fumigatus spore levels appeared to be related
to the composting facility (Syzdek and Haines 1995; Recer et al., 2001).
The report presented here describes the symptom diary portion of the study. Daily
recording of a variety of health symptoms by study participants provided data about
daily changes in symptom occurrence. These data were analyzed in relation to spore con-
centrations observed during the same time period. Our analysis focuses on the relation-
ship between health symptom occurrence among members of community living near the
composting facility and spore concentrations measured in that community. Symptom
diaries were also completed by residents of a reference community not exposed to the
composting facility. Patterns of health symptom occurrence among residents of the ref-
erence community were used to provide information on seasonal trends and other vari-
ations in symptom reporting not affected by exposure to composting facility emissions.
Methods
Study and Comparison Areas
The study area was selected based on historical records of prevailing wind direc-
tion. The neighborhood northeast of the facility was determined to be the most likely
one exposed to any bioaerosols transported by air from the composting facility. A com-
parison community more than five miles from the facility, not in the direction of the
prevailing winds, and with demographic characteristics similar to the study neigh-
borhood, was chosen.
Environmental Sampling
Burkard spore-trap samples for airborne fungal spore enumeration were collect-
ed continuously from August 21 through November 30, 1992 at four sites: 1) the Islip
Composting Facility; 2) a location in the study neighborhood; 3) a location in the ref-
erence neighborhood; and 4) a second reference location southwest of the facility. A
detailed description of the sample collection and processing methods can be found in
Syzdek and Haines 1995. Two four-minute time-weighted-average counts of fungal
spore concentration were obtained from each 24-hour sample to estimate daily expo-
sure across the entire study period. Preliminary four-minute counts indicated that sub-
stantial temporal variation could occur in spore levels during a 24-hour interval. There-
fore, 24 one-hour time-weighted-average counts per day were also completed for a
period of 20 consecutive days during the study period. The one-hour counts were per-
formed for the study neighborhood sampling site only. During the 20-day period, a
substantial amount of variation in daily symptom frequencies was reported among
participants from the study area. However, this period had relatively little variability
in average daily temperature and ozone levels.
242 Compost Science & Utilization
Summer 2001

A Prospective Study of Health Symptoms and Aspergillus fumigatus Spore Counts
Near a Grass and Leaf Composting Facility
Temperature, ozone, sulfur dioxide and nitrogen dioxide data were obtained from
a New York State Department of Environmental Conservation continuous air moni-
toring station located about 40 kilometers (25 miles) west of the composting facility.
Ragweed count data were provided by a nearby pollen counting station (Deer Park,
New York).
Symptom Diary Study
In order to identify candidates for inclusion in the symptom diary study, self-com-
pletion questionnaires were distributed door-to-door to all households in the study area
(384) and in the comparison community (1108). Information was provided for 491 in-
dividuals in the study area and 619 in the comparison area. A large proportion of those
persons reporting a physician diagnosis of allergic rhinitis and/or asthma were invit-
ed to participate in the symptom diary study. Study candidates were frequency-
matched so that approximately equal numbers were selected from each community by
sex and ten-year age category, with no more than two persons from a single household.
A one-page symptom diary was developed consisting of daily checklists for a
one-week period. Participants were asked to check “no,” “slight” or “moderate/se-
vere” for each of ten health symptoms: eye irritation, stuffy/runny nose, sore throat,
coughing, wheezing, difficulty breathing, nausea/upset stomach, skin rash, joint
pain, and cold/flu. Several additional questions regarding activities and use of med-
ications were included. Participants were asked to complete daily diaries for the pe-
riod 8/9/92 through 10/31/92. Since environmental monitoring did not begin at all
sample locations until August 21, diary data for 8/9/92 through 8/20/92 were ex-
cluded from the analysis.
Data Analysis
For each participant, days for which diary data were missing and days for which
hours at home were less than six were removed from the total number of eligible re-
porting days. Since an allergic response to a single exposure can persist for several
days, a participant who reported a particular symptom the day before was only con-
sidered eligible to report a symptom event if there was an increase in symptom sever-
ity for that participant from one day to the next. That is, if a symptom was reported as
“moderate/severe”, the participant was eligible to report a symptom event if the re-
sponse on the previous day was either “no” or “slight” for that symptom. After tally-
ing individual symptom events; eye irritation, stuffy/runny nose, sore throat, cough-
ing, nausea/upset stomach, skin rash, and joint pain were grouped together as
symptoms indicative of allergic or irritative responses (hereafter allergy symptoms).
Wheezing, difficulty breathing, and coughing were grouped together as asthma-relat-
ed symptoms. Incidence rates were computed as the number of participants reporting
incident symptom events (one or more allergy symptom events, one or more asthma
symptom events) divided by the number of participants eligible to report symptoms.
To account for possible delays in symptom occurrence and recognition from one
day to the next, a lagged incidence (Ponka 1991; Pope et al. 1991) was computed. All
symptom incidence analyses were performed using both the “unlagged” and “lagged”
symptom incidence rates, producing similar results. Only results using the unlagged
rates are presented in this report.
Since symptom incidence is a count of symptom events per day, Poisson re-
gression analysis was used (Frome 1983). A. fumigatus spore concentration was an-
Compost Science & Utilization
Summer 2001 243

Marilyn L. Browne, Carole L. Ju, Gregg M. Recer, Lee R. Kallenbach,
James M. Melius and Edward G. Horn
alyzed as an independent variable. Temperature, ozone, sulfur dioxide, nitrogen
dioxide and ragweed pollen have all been associated with respiratory symptoms
and were considered as potential predictors of symptom occurrence. In addition,
time since start of the study was considered due to its representation of seasonali-
ty and because of “fatigue effect”(Abramson 1990) (a tendency to report fewer
symptoms over the course of a diary study). A number of these factors would be ex-
pected to be correlated. For example, as the study period progressed from August
through October (i.e., time since start of the study increased), temperature and rag-
weed would have been expected to decrease. To control for a number of intercorre-
lated factors, factor analysis was used to compute a “combined factor” to represent
the levels of all the component variables for each day. A number of the variables
evaluated in this study had values with non-normal distributions (spore counts,
ragweed counts, ozone levels). When analyzed as continuous variables, the natur-
al logarithm was used.
The range of observed values for the independent variables was divided into quar-
tiles to permit calculation of rate ratios. Rate ratios, with 95% confidence intervals,
were calculated as the ratio of symptom incidence for the second, third or fourth quar-
tile of the independent variable of interest to the symptom incidence for the first quar-
tile (the referent). A rate ratio significantly different from one indicates a significant
difference in symptom incidence compared to the referent quartile.
Analyses based on the entire study period (using 4-minute counts) and the 20-day
period (using 1-hour counts) are presented separately. In analyzing data for the 20-day
interval, factors shown to predict symptom incidence during the entire study period
were considered as potential predictors for the 20-day interval. Also, a paired t-test was
used to compare symptom prevalence on selected days having either low or high A.
fumigatus concentrations. Only participants for whom data were available for each of
the selected days were included in this analysis. The “low A. fumigatus days” had to
be preceded by at least one other day with a relatively low A. fumigatus concentration.
This was done in order to reduce the influence of delayed responses that might carry
over from exposure on the previous day.
Results
A total of 237 candidates, 116 from the study area and 121 from the reference area,
were invited to participate in the symptom diary study. At initial telephone follow-up,
eight refusals were identified, five of whom were no longer eligible due to a change in
residence. During the course of the study, 53 persons from the study area and 38 from
the reference area either refused participation or provided sparse data. One addition-
al subject from the reference area was excluded from the analysis due to serious chron-
ic disease. A total of 63 participants (54% of original candidates) from the study area
and 82 participants (68% of original candidates) from the reference area were includ-
ed in the analysis.
Entire Study Period
Daily allergic and irritant symptom incidence averaged 21.4% among study area
participants and 16.5% among reference area participants. Asthma-related symptom
incidence average 7.8% and 5.0% for study area and reference area participants, re-
spectively. Among both study and reference area participants, incidence rates for both
allergy and asthma symptoms declined over the course of the study period.
244 Compost Science & Utilization
Summer 2001

A Prospective Study of Health Symptoms and Aspergillus fumigatus Spore Counts
Near a Grass and Leaf Composting Facility
TABLE 1.
Summary statistics for ragweed pollen, temperature and chemical air contaminants for the
entire study period (72 days). Ragweed values are 24-hour time-weighted averages.
Temperature and chemical values are daily maximum observations.
Standard
Mean
Range
Deviation
Maximum temperature (°F)
71
45-95
11
Maximum ozone level (ppm)*
Maximum nitrogen dioxide (ppm)**
Maximum sulfur dioxide (ppm)
0.044
0.046
0.013
7.7
0.016-0.126
0.007-0.113
0.001-0.037
0-67
0.021
0.02
0.008
12.2
3
Ragweed pollen (grains/m )
* ppm = parts per million.
**Nitrogen dioxide data were available for 62 days.
Analyses were performed to determine whether air quality parameters were asso-
ciated with incident symptoms on a daily basis. Ozone, sulfur dioxide, nitrogen diox-
ide, temperature and ragweed pollen results for the entire study period were examined
(Table 1). Sulfur dioxide and nitrogen dioxide levels were not associated with increased
symptom incidence. Ozone, ragweed, temperature and time since start of the study were
each significantly (p<0.05) associated with allergy and asthma incidence in separate
Poisson models. These four variables were intercorrelated (r=0.66 to 0.83), prompting
the use of factor analysis to compute a single “combined factor” to account for the in-
fluence of all four variables in a single Poisson regression model. Among study area par-
ticipants, the combined factor was significantly associated with the frequency of inci-
dent allergy and asthma symptoms. The rate ratios tended to increase for the higher
quartiles of the combined factor in a dose-response fashion. For the reference area, a sig-
nificant positive relationship was observed between the combined factor and the inci-
dence of allergy symptoms; however, the relationship was not significant for the inci-
dence of asthma symptoms (Table 2).
Daily mean and maximum A. fumigatus concentrations (four-minute time-
weighted averages; Table 3) were each evaluated by Poisson regression analysis for
TABLE 2.
Symptom incidence rate ratios for quartiles of a “combined factor”
obtained from factor analysis of ragweed, ozone, temperature and time
since start of study using data for the entire study period.
Study Area
Reference Area
# Events/
# Eligible
Rate ratio (95%
Quartile Confidence Interval) # Eligible
# Events/
Rate Ratio (95%
Quartile Confidence Interval)
Symptoms
Allergy
793/2879
279/3271
4
3
2
1
4
3
2
1
1.85 (1.47-2.34)*
1.71 (1.36-2.17)*
1.35 (1.06-1.73)*
1.0
746/3764
226/4257
4
3
2
1
4
3
2
1
1.58 (1.26-2.00)*
1.42 (1.12-1.79)*
1.31 (1.04-1.66)*
1.0
Asthma
1.61 (1.14-2.27)*
1.17 (0.81-1.67)
0.97 (0.66-1.43)
1.0
1.16 (0.79-1.71)
1.18 (0.80-1.74)
1.10 (0.74-1.62)
1.0
* p-value < 0.05, statistically significant.
Compost Science & Utilization
Summer 2001 245

Marilyn L. Browne, Carole L. Ju, Gregg M. Recer, Lee R. Kallenbach,
James M. Melius and Edward G. Horn
TABLE 3.
Summary statistics for daily A. fumigatus for the entire study period (72 days) and for the
20-day period. A. fumigatus spore concentrations for the entire study period are mean or
maximum 4 minute time-weighted averages (2 or 3 per day). A. fumigatus spore
concentrations for the 20-day period are mean or maximum one-hour time-weighted
averages (24 per day) for the study area only.
3
A. fumigatus spore concentration (spores/m )
Standard
Mean
Range
Deviation
N
72-day study period
Daily average
Reference area
44
0 - 230
0 - 4710
0 - 830
60
72
72
72
Study area
180
120
566
160
Study area (highest value censored)
Daily maximum
Reference area
87
0 - 452
120
1700
400
72
72
72
Study area
470
270
0 - 14,000
0 - 2000
Study area (highest value censored)
20-day period – Study area only
Daily average
130
2 - 830
210
20
20
Daily maximum
“High” days
2300
58 - 19,000
4600
Daily average
350
160 - 830
250
6
6
Daily maximum
6400
2100 - 19,000
6200
“Low” days
Daily average
Daily maximum
20
2 - 44
16
6
6
300
58 - 680
260
TABLE 4.
Symptom incidence rate ratios for quartiles of maximum daily A. fumigatus spore level based
on 4 minute counts using data for the entire study period. Rate ratios were adjusted for a
“combined factor” obtained from factor analysis of ragweed, ozone, temperature
and time since start of the study.
Study Area
Reference Area
Symptoms
Allergy
# Events/
# Eligible
Rate Ratio (95%
Quartile Confidence Interval) # Eligible
#Events/
Rate Ratio (95%
Quartile* Confidence Interval)
793/2879
279/3271
4
3
2
1
4
3
2
1
1.08 (0.86-1.35)
1.09 (0.87-1.37)
1.02 (0.82-1.29)
1.0
746/3764
226/4257
4
3
1
0.87 (0.71-1.06)
1.05 (0.87-1.27)
1.0
Asthma
0.83 (0.58-1.18)
1.08 (0.77-1.52)
0.95 (0.67-1.34)
1.0
4
3
1
0.82 (0.58-1.15)
0.88 (0.63-1.22)
1.0
* For the reference area, 47.2% of daily A. fumigatus values were 0, therefore quartiles 1 and 2 were combined.
their relationship to allergy and asthma symptom incidence. For both daily mean
and daily maximum A. fumigatus concentrations, neither the unadjusted model nor
the model adjusting for the combined factor showed a positive association. The ad-
justed symptom rate ratios for quartiles of maximum daily A. fumigatus spore levels
are presented in Table 4.
246 Compost Science & Utilization
Summer 2001

A Prospective Study of Health Symptoms and Aspergillus fumigatus Spore Counts
Near a Grass and Leaf Composting Facility
Twenty Days with 1-hour A. fumigatus Spore Counts
One-hour time-weighted average A. fumigatus spore counts (24/day) were per-
formed for the study neighborhood sampling site only. For this reason, the relation-
ships between 1-hour A. fumigatus spore concentrations and health symptoms are ex-
amined for study area participants only. Daily mean and maximum 1-hour A.
fumigatus spore concentrations (Table 3) were each evaluated and were not associated
with increases in the incidence of allergy or asthma symptoms. The results of the Pois-
son regression analysis using maximum daily A. fumigatus spore counts adjusted for
ragweed and time since start of the study are shown in Table 5. Ozone and tempera-
ture varied little over the 20-day study period and therefore did not require adjust-
ment. Each of the individual symptom incidence rates (eye irritation, runny nose, skin
rash, etc.) were also analyzed using Poisson regression analysis and no significant pos-
itive associations between A. fumigatus counts and symptom incidence resulted.
Within the 20-day period, symptom frequencies on six days with the highest A. fu-
migatus counts were compared to symptom frequencies on six days with relatively low
A. fumigatus levels using a paired t-test. Daily maximum 1-hour A. fumigatus counts
ranged from 58 - 680 spores/m3 on “low” days to 2,100 - 19,000 spores/m3 on “high”
days. High A. fumigatus spore counts were not associated with increased reporting of
allergy or asthma symptoms.
The mean (intra-individual)
difference in the number of
days reporting an allergy
symptom for the 6 high A. fu-
migatus days versus the 6 low
A. fumigatus days was 0.04
(standard error=0.15). For
asthma symptoms, the mean
difference in symptom fre-
quency was -0.29 (standard
error=0.18) for the 6 high A.
fumigatus days versus the 6
low A. fumigatus days. Rag-
weed pollen and time since
start of the study were not
controlled for in these analy-
ses due to the small number of
days being analyzed.
TABLE 5.
Symptom incidence rate ratios for quartiles of
maximum A. fumigatus counts for the 20 days for which
1-hour A. fumigatus counts were available (study area
only). Rate ratios are adjusted for daily ragweed count
and time since start of the study.
# Events/
# Eligible
Rate Ratio (95%
Confidence Interval)
Quartile
Allergy
Asthma
271/847
4
3
2
1
4
3
2
1
1.11 (0.76-1.62)
0.59 (0.38-0.92)
0.90 (0.58-1.39)
1.0
93/983
0.48 (0.26-0.89)*
0.47 (0.24-0.93)*
0.48 (0.25-0.92)*
1.0
* p < 0.05, statistically significant.
Discussion
A symptom diary approach was used to evaluate the relationship between
bioaerosol concentrations, in particular A. fumigatus spore concentrations, and respi-
ratory symptoms associated with allergic, irritative or general inflammatory respons-
es. In a diary study, individual symptom patterns can be related to exposure measures,
allowing the population of interest to serve as its own control. With this method, fac-
tors which could be difficult to control for in a cross-sectional comparison study would
not confound the relationship under examination.
During the 20-day period for which we obtained 1-hour counts, a fairly wide range
in spore counts was observed. However, increases in symptom incidence were not as-
sociated with the elevations in these counts among participants in the study area. Thus,
Compost Science & Utilization
Summer 2001 247

Marilyn L. Browne, Carole L. Ju, Gregg M. Recer, Lee R. Kallenbach,
James M. Melius and Edward G. Horn
although the counts of A. fumigatus spores measured in air in the community near the
composting facility were somewhat higher than those for the reference community
(Syzdek and Haines 1995; Recer et al., 2001), increased rates of health symptoms in re-
sponse to elevations in A. fumigatus counts were not demonstrated in this study.
An important limitation of the study is that data providing reliable estimates of
average daily A. fumigatus spore counts were only available for approximately one-
quarter of the original study period. The sharp short-term fluctuations observed in
spore levels were not anticipated. Modifying the spore-count method to average over
these short-term fluctuations reduced the sensitivity of the original approach for re-
lating daily spore exposure to symptom incidence. Also, fungal spore counts at the
sampling locations are probably only an approximate measure of individual exposure
to fungal spores, which may have further limited our ability to detect associations. In-
door spore counts may differ significantly from those measured outdoors, and many
people spend most of their time indoors. In addition, other indoor and outdoor envi-
ronments away from home may have an effect on symptom occurrence.
It was our intent to have each subject act as his or her own control by using a
method of data analysis which produces a summary estimate based on separate logis-
tic regression of data for each subject in the study (Korn 1979). Losses due to dropouts
from the study and gaps in the data due to incomplete or missing diaries did not per-
mit the use of that method of data analysis. For Poisson regression analysis of incidence
rates, participants do not serve as their own controls. Therefore, there is the potential
for differences in individual susceptibility to confound the relationship being evaluat-
ed. While participants do act as their own controls in the paired t-test of differences in
symptom prevalence, data sparseness limited that analysis to 12 days and 48 partici-
pants. The t-test analysis had a 63% to 91% probability of correctly identifying in-
creases of 10% to 15%, respectively, in the frequency of allergy or asthma symptom re-
porting on high A. fumigatus days versus low A. fumigatus days. Thus, while it is likely
that a true increase in symptom frequency of 15% or more would have been detected,
a 10% or smaller increase could have been missed.
Despite the limitations described above, it is interesting to note that symptom in-
cidence was associated with ragweed, ozone, temperature and time since start of the
study. This was true for participants living near the composting facility and, to a less-
er degree, participants from the reference community. The presence of a dose-response
trend suggests that changes in one or more of these variables are having an effect on
symptom incidence. If ragweed, ozone and temperature are independently related to
symptom incidence (and not just in association with time since start of the study), our
ability to assess the effect of environmental influences on allergy and asthma symp-
tom occurrence would be supported. However, time since start of the study was
strongly correlated with ragweed, ozone and temperature and could provide an alter-
native explanation for the decrease in symptom incidence observed over the course of
the study. A general tendency to report fewer symptoms as a study progresses, termed
a “fatigue effect,” has been noted in other studies using diary data (Abramson 1990).
Separating the relative importance of the environmental factors and time since start of
the study was not possible due to their strong intercorrelations.
The results of this study suggest that if elevated concentrations of A. fumigatus
spores due to operations at the composting facility are causing increases in allergy and
asthma symptom prevalence, the increase was too small for us to detect given the study
limitations. We propose that future studies employ more objective measures of im-
mune response and respiratory function. Also, less labor-intensive exposure measures
that can reliably assess individual daily bioaerosol exposures would be desirable.
248 Compost Science & Utilization
Summer 2001

A Prospective Study of Health Symptoms and Aspergillus fumigatus Spore Counts
Near a Grass and Leaf Composting Facility
Acknowledgments
We thank those who provided the environmental monitoring data used in this
study: John Haines and Larry Syzdek for the Aspergillus fumigatus counts and Syril Far-
ber for the ragweed pollen data. Lenore Gensburg and Syni-An Hwang assisted in the
data analysis. Margaret Gadon provided guidance regarding medical issues.
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