Controlled Human Exposure to Indoor Air, Dust and Ozone

The aim of the study is to provide information which may help to improve the quality of the life of persons exposed to indoor environments in Danish dwellings.

The experiment will document if dust and ozone contribute to deterioration of indoor air quality and to the occurrence of symptoms and health effects.

The study is aimed at testing the hypothesis that the presence of ozone potentiate the health and comfort effects of dust exposure in the indoor environment.

Testing this hypothesis will be based on the following questions:

Does house dust and ozone in concentrations frequently encountered in Danish dwellings cause unwanted health effects either by themselves or by interaction?

If so, does the presence of ozone potentiate the expected irritative effects of dust?

The challenge of these hypotheses will be made as a controlled experiment on humans in a climate chamber under controlled exposure conditions.

This controlled human experiment should be able to substantiate the findings from the intervention studies.

Furthermore, they ideally reflect something relevant to the general public and therefore should have maximum public appeal and application possibilities.

This study is a part of a broader research programme established by CISBO ( Centre for Indoor air and Health in Dwellings). The purpose of the centre is to increase the general knowledge and to provide information on indoor air quality and related Health effects. The study may contribute with basic information on underlying pathophysiological mechanisms involved in human responses to these pollutants and in their interactive effects. The study includes as methods and techniques to detect minor changes in biomarkers suggesting early effect of exposure. These analyses will give information at a high sensitive level about the exposure effects on biomarkers for an array of symptoms and reactions.

The study Group consitss of 24 non-smoking persons(aged 60-70). A controlled, randomized and balanced Latin square cross-over design using the participants as their own controls. The exposures are arranged in a full-scale climate chamber where the participants will be exposed for 5½ hour under controlled environmental conditions.

The exposure facility (Climate chamber):

The exposures are arranged at the controlled experimental facilities at our department which include climate chambers and exposure generators for dust and ozone. The exposure sessions will take place under controlled conditions in a 79 m3 climate chamber made of welded stainless steel optimized for experiments with gasses and particulate air pollutants. The chamber facility allows exposures with controlled ventilation, temperature and air humidity and has an efficient mixing of ventilation air with the chamber air.

All participants will attend all four diff. exposure sessions:

Dust (250-300µg/m3), Ozone (0,1ppm ozone),Dust+ozone (250-300µg/m3 + 0,1 ppm ozone), Filtered air (\<20µg/m3). with at least 2 weeks between each exposure session to eliminate hang-over effects. The filtered air and dust and ozone contaminated sessions will be identical except for the air quality. The exposures are unknown to the participants and staff to keep the study double blinded. The blinding will be continued until the basic statistical analyses have been conducted.

Selected subjective and objective health outcomes are measured at baseline and at follow-up at predefined time points.

Health assessment and Measurements includes:

Subjective symptoms, Respiratory outcomes (lung function, FENO, exhaled breath condensate, nasal lavages, Acoustic Rhinometri) Blood samples (inflammation biomarkers)

Eligibility Criteria:
Inclusion Criteria:

* Non-smoker
* Normal lung function
* No active allergic rhinitis
* Be free from clinically significant cardiac, pulmonary, neurological and psychiatric disease as determined by medical history, physical examination and screening investigations.
* With no clinically-significant deviation outside the normal ranges for blood presure and pulse Measurements.
* Capable of giving informed consent
* Be avaible to complete the study
* Provide oral and written informed consent to participate in the study

Exclusion Criteria:

* Atopy
* Upper respiratory tract infection within 2 weeks
* Medical conditions likely to affect the outcome of the study in the opion of the investigator.
* Presence of any respiratory disease
* Infection of the upper Airways/lower Airways includingviral infections in the 14 days prior to screening and at the start of/or during the study.