Acoustic rhinometry in epidemiological studies - Nasal reactions in Swedish schools

A cross-sectional study was performed on the relationships between hygienic measurements and nasal investigations in 234 personnel in 12 primary schoo ls in mid-Sweden. Hygienic data included building characteristics, measurem ents of indoor air pollutants, air change rate, temperature and humidity. C linical examinations included symptom reports, acoustic rhinometry and nasa l lavage, with the determination of biomarker levels for eosinophil cationi c protein (ECP), lysozyme, myeloperoxidase (MPO) and albumin. Subjective na sal obstruction was increased in schools with mechanical ventilation (adjus ted prevalence OR=2.0; 95 CI 1.1-3.7) and subjects reporting nasal obstruct ion had higher levels of dust in the classroom, compared to those not repor ting this symptom (p = 0.008 by Mann-Whitney U-test). Congruently, a decrea sed nasal patency measured by acoustic rhinometric minimum cross-sectional areas (MCA1 and MCA2) was related to the use of mechanical ventilation (p=0 .008 and p=0.02 respectively, by Mann-Whitney U-test), dust levels (p=0.03 and p<0.001 respectively, by Kendall's tau correlation analysis), a lower c leaning frequency of desks (p <0.001 and p=0.02 respectively, by Kendall's tau correlation analysis), the use of wet mopping (p<0.001 and p=0.04 respe ctively, by Mann-Whitney U-test) and PVC floor material (p<0.001 and p=0.03 4 respectively, by Mann-Whitney U-test). The cleaning frequency of floors w as positively correlated with MCA1 (p=0.049 by Kendall's tau correlation an alysis). In buildings with signs of water damage, flat roof or a concrete s lab fundament the personnel had increased ECP, lysozyme or albumin levels i n nasal lavage. A reduced nasal patency and an increased inflammatory bioma rker response were seen for higher levels of formaldehyde (MCA1, MCA2, VOL1 , VOL2, ECP and lysozyme) and nitrogen dioxide (MCA1, VOL2, ECP and lysozym e) in the classrooms. In conclusion, the results indicate that acoustic rhi nometry in combination with the determination of nasal lavage biomarkers ca n be used to study effects on the upper airways of the indoor environment. Actual exposures to indoor air pollutants in Swedish schools can affect the occurrence of subjective nasal obstruction and give clinical signs of redu ced nasal patency together with an inflammatory biomarker response in the n asal mucosa.