Karlsson AS, Renstrom A, Hedren M, Larsson K. Allergy. 2004;59:661–667
Purpose of the Study.
To determine if feasible and economically defensible classroom interventions that do not interfere with pet ownership can alter airborne levels of cat allergen.
Intermediate-level school classrooms (n = 25, grades 1–6) in a suburb north of Stockholm, Sweden. Only classrooms with a single group of students using the class during the study period were used. Flooring materials, ventilation, cleaning routines, and room size were similar. The mean number of children per classroom was 25 (range: 18–30), and 21% had cats at home.
Three categories of classrooms were compared: 14 control classrooms, 5 previously established allergy-prevention classrooms using criteria for allergen avoidance established by the Swedish National Institute of Public Health and Swedish Asthma and Allergy Association (ie, new building; increased cleaning routines; removal of upholstery, curtains, carpets, and plants; and replacement of open bookshelves with closed cupboards to reduce dust accumulation), and 6 were intervention classrooms. The study involved 1 school year divided into 2 terms. At the start of the second term, avoidance measures were introduced into the intervention classrooms. These classrooms were cleaned thoroughly, bookshelves were replaced with closed cupboards, curtains, upholstery, and plants were removed, upholstered staff chairs were treated with tannic acid, and fabric notice boards were coated with an acrylic paint. Classroom cleaning was increased from twice weekly to daily. Airborne dust was sampled continuously by using weekly Petri-dish collections and personal air-sampler collections. All dish samples and air samples were analyzed for cat allergen (Fel d1) by immunoassay.
No significant difference was noted for airborne cat-allergen levels during the study period between allergy prevention, intervention, and control classes by either Petri-dish collection or personal air sampling. Additionally, there was no difference in cat-allergen level in the intervention classroom before or after the intervention measures. Airborne cat-allergen levels were significantly lower in classes with few cat owners (<21%) compared with classes with many cat owners (>21%).
Multiple simultaneous allergen-avoidance measures failed to influence airborne cat-allergen levels. The number of cat owners associated with each classroom was the predominant factor contributing to the level of cat allergen found.
Several studies have shown that pet allergens can be found in school classrooms. The relationship between cat-allergen level in classrooms and the number of cat owners per class has also been established. Indirect transfer of the allergen, primarily by clothing, has been implicated. In this study, practical, economical measures failed to impact the cat-allergen levels. Although clinical outcomes were not measured in this study, it is probable that no improvement would have been seen for cat-allergic children. These results suggest that, as the authors indicated in their concluding remarks, more significant interventions such as minimization of pet ownership and use and development of special clothing may be required for seriously pet-allergic children.