Health effects on workers in Oxygen-reduced atmosphere for fire prevention

Status:

completed 01/2010

Aims:

Study of impact of stay and work in normobaric hypoxia (down to 13 Vol%) on the incidence of acute and chronic complaints and illnesses.

Activities/Methods:

Cohort study of persons exposed at the workplace and non exposed persons in Germany during one year.

Results:

Most of the exposed persons had at time of inclusion in the cohort an average of two years experience working in oxygen reduced atmosphere; 43 persons entered the oxygen reduced work areas for the first time after inclusion in the cohort. About 2/3 of the exposed worked in rooms with an oxygen concentration equal to 15 vol% or higher, about 1/3 worked in areas with 13 to 15 vol% oxygen. Almost 95% of the exposed had an average time of exposure shorter than one hour per exposure. Exposed subjects and controls corresponded in most of the characteristics, especially the internal company controls differed only faint from their exposed colleagues. The differences between exposed and control subjects were mathematically adjusted in the performed analysis.
Neither the daily first month questioning (diary), nor the monthly questionnaires during the following eleven months, resp. the final examination could reveal an over-frequency (higher occurrence) of complaints and diseases in relation to work in oxygen reduced atmosphere; a tendency in lower scores of hypoxia-typical complaints was found in the exposed subjects. New-exposed persons did not differ from subjects, which were already exposed at starting time regarding complaints and diseases; a healthy worker effect cannot be assumed.
In the group of exposed persons - according to the diary data - subjects working in lower oxygen concentrations (< 15 vol%) and co-requisite physical demands (effort) had cardio-pulmonary complaints (shortness of breath, palpitations, weight on the chest) more often, likewise while additional ambient stress. Ambient stress and shift work increased the risk for high altitude complaints (headache, dizziness / light headedness, fatigue, nausea). The monthly acquired data revealed similar results.
Complaints, mainly dizziness, forced 15 persons in a one year period to leave the oxygen reduced atmosphere temporarily; these persons worked also mainly physical, in rooms with lower concentration of oxygen and mentioned more pre-existing diseases. In the final examination other health complaints were not mentioned more often by the exposed persons compared to the controls. The haemoglobin concentration measured at starting time of the study was slightly higher (about 0.2 g/dl) in exposed subjects than in controls; the change during the study year was not different between the groups. The arterial blood pressure lowered in the entire study group evenly in the exposed and control persons.

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