Indoor air exposure to brominated flame retardants in public primary schools and associations with childhood respiratory and skin outcomes

Despite widespread use of polybrominated diphenyl ethers (PBDEs) and other brominated flame retardants (BFRs) in indoor environments, data on children's BFR exposure in Portuguese schools and associated health effects remain limited. We aimed to characterize indoor air BFR concentrations in 20 Portuguese primary schools, examine grade-specific exposure patterns, and investigate the associations between BFR concentrations and childhood asthma, wheezing, and eczema. Air BFRs were measured using passive sampling in 80 classrooms over 28 days. Health outcomes (lifetime asthma history, current asthma, wheezing, and eczema) were obtained from standardized parental questionnaires. Multilevel logistic regression models accounting for school-level clustering evaluated associations between log-transformed concentrations and health outcomes, adjusting for relevant confounders. The sum of BFR (∑BFR) concentrations ranged between 28.12 and 154.54 pg/m³ . Replacement BFRs, particularly decabromodiphenyl ethane (DBDPE), were dominant contributors, while BDE-47 and BDE-209 remained prevalent among legacy compounds. Grade 1 students exhibited higher exposure to several BFRs than older students. Per log10-unit increase, BDE-209 was associated with higher odds of lifetime asthma history (OR=2.13; 1.09-5.11) and wheezing (OR=1.75; 1.17-3.18), while an increase in ∑BFRs (OR=1.93; 1.29-3.91) was associated with higher odds of current asthma. Furthermore, a log10-unit increase in ∑non-BDEs was associated with a significantly higher eczema odds (OR=2.88; 1.65-5.46). Children in schools are exposed to legacy and replacement BFRs, with patterns varying per grade. The prominence of replacement compounds underscores an ongoing transition in indoor BFR profiles, reinforcing the need for targeted mitigation strategies and continued evaluation of potential health risks to children.