Indoor Air Quality in Two Urban Elementary Schools—Measurements of Airborne Fungi, Carpet Allergens, CO₂, Temperature, and Relative Humidity

This article presents measurements of biological contaminants in two elementary schools that serve inner city minority populations. One of the schools is an older building; the other is newer and was designed to minimize indoor air quality problems. Measurements were obtained for airborne fungi, carpet loadings of dust mite allergens, cockroach allergens, cat allergens, and carpet fungi. Carbon dioxide concentrations, temperature, and relative humidity were also measured. Each of these measurements was made in five classrooms in each school over three seasons—fall, winter, and spring. We compared the indoor environments at the two schools and examined the variability in measured parameters between and within schools and across seasons. A fixed-effects, nested analysis was performed to determine the effect of school, season, and room-within-school, as well as CO₂, temperature and relative humidity. The levels of all measured parameters were comparable for the two schools. Carpet culturable fungal concentrations and cat allergen levels in the newer school started and remained higher than in the older school over the study period. Cockroach allergen levels in some areas were very high in the newer school and declined over the study period to levels lower than the older school. Dust mite allergen and culturable fungal concentrations in both schools were relatively low compared with benchmark values. The daily averages for temperature and relative humidity frequently did not meet ASHRAE guidelines in either school, which suggests that proper HVAC and general building operation and maintenance procedures are at least as important as proper design and construction for adequate indoor air quality. The results show that for fungi and cat allergens, the school environment can be an important exposure source for children.

Keywords:

• carpet allergens
• cat
• culturable airborne fungi
• culturable carpet fungi
• cockroach
• dust mite

ACKNOWLEDGMENTS

We are especially grateful to Ken Meyer and others at the Minneapolis Public Schools for their help in making this study possible. The cooperation we received from the principals, school teachers, nurses, custodians, building engineers, and students at the Lyndale and Whittier schools is deeply appreciated.

We also thank Georg Fischer of the Minnesota Department of Health, and Paul Ellringer for their help with the measurements.

This research was funded by the U.S. Environmental Protection Agency.

Notes

^A Estimate based on the fact that it was common practice for buildings of this vintage to be supplied with outdoor air at a rate equal to 10 cfm per occupant. Thus, for an average occupancy of 25, each classroom is supplied with 7.08 m³/min (250 cfm) of outdoor air.

^B A MERV (minimum efficiency reporting value) rating of 8 implies that the filter is at least 70–85% efficient in capturing particles between 3–10 μ m.

^A N is the number of daytime averages calculated for the four comfort parameters for all sampling locations over the 2-week study period during each season. Each daytime average is a grand mean of all the 5-min averages measured between 8:00 a.m. and 6:00 p.m.

^B Values within parentheses are for the outside.

^A N is the number of nighttime averages calculated for the four comfort parameters for all sampling locations over the 2-week study period during each season. Each nighttime average is a grand mean of all the 5-min averages measured between midnight and 8:00 a.m.

^B Values within parentheses are for the outside.

^A N = the number of sampling days for which daytime averages were calculated for temperature and relative humidity for all sampling locations over the 2-week study period during each season.