Controlled human exposure to indoor air, dust, and ozone; XDOZ

Background: Modern citizens spend approximately 90 % of their time indoor. Several studies have indicated that airborne particulate matter and dust affect the comfort and health of occupants of normal non-industrial buildings.Aim: To test if the presence of ozone potentate the discomfort and health effects of dust exposures in the indoor environment.Methods: A double blinded cross over study design was applied with the participants acting as their own controls. 23 non-smoking participants (aged 60-70) with normal lung function and without bronchial hyper-responsiveness were included in the study. All participants were subjected to four different exposure scenarios in the climate chamber.Exp. 1: Dust (250 – 300 µg/m3)Exp. 2: Ozone (100 ppb)Exp. 3: Dust (250 – 300 µg/m3) + ozone (100 ppb)Exp. 4: Filtered air (<20µg/m3)The exposure time was 5½ hours for each session.The health effects were evaluated at baseline and specific follow-up times in relation to selected respiratory and cardiovascular outcomes, such as; nasal volume, exhaled nitric oxide (FENO), spirometry (FEV1 and FVC), exhaled breath condensate (EBC), nasal lavage, blood samples, EndoPat. Questionnaires were used for assessment of subjective symptoms and general perception of the indoor environment.Results: For most of the participants’ no symptom variation was seen with varied exposures. However for the FVC and the FEV1/FVC ratios a significant association with different chamber exposures were seen.Conclusion: The dust and ozone levels applied in the study did not cause apparent adverse effects in the participants. We found greater variation within participant than between participants for the standard parameters investigated.