Background: Cockroach allergen, Bla g 1, is an important indoor allergen. Although household exposure has been documented, little is known about the potential for exposure outside the home.
Objective: We investigated the settled dust concentration of Bla g 1 in 147 samples collected from classrooms, kitchens, cafeterias, and other sites in four primary schools in the city of Baltimore.
Methods: School authorities were questioned about characteristics of schools, teachers, and students, as well as cockroach control and cleaning procedures. Settled dust samples were collected with a hand-held vacuum cleaner from the floors of all classrooms, food-related areas, and other sites of the schools over a 3-week period. A sample collection in each school took 1 to 2 days. Dust samples from each room were pooled and analyzed as a single sample for Bla g 1 by using a two-site monoclonal ELISA.
Results: One hundred two (69%) of the 147 samples had detectable Bla g 1 and were within the range reported by other investigators in inner city homes. There was no difference between the median levels of Bla g 1 in three schools: school 1 (5.2 U/gm), school 2 (3.0 U/gm), and school 4 (2.7 U/gm); but school 3 had a significantly lower level (< 0.8 U/gm, p < 0.001). The median level from the food-related areas was significantly higher than the median classroom level (p = 0.048). School 3 had fewer students on subsidized lunch, fewer African-American students, and fewer students per teacher. Bla g 1 levels were compared in the different schools while controlling for potential confounding variables by a stepwise multiple regression analysis with a logit model for ordinal responses. On the basis of this analysis, Bla g 1 levels in schools 1, 2, and 4 differed significantly from levels in school 3 (p < 0.001 in each case). Food-related areas had significantly higher levels than classrooms (p = 0.048). Floor level, the presence of a sink, and the presence of carpeting did not have significant effects.
Conclusions: We conclude that Bla g 1 is detectable at potentially significant concentrations in some inner city schools. Furthermore, the level of exposure is different between different schools and between sites within individual schools.