Participants for the second intervention were recruited from one of the companies taking part in the first intervention. The 120 non-smoking employees reporting most mucous membrane complaints were selected. They were assigned to an intervention or a control group, so that the two groups had a similar distribution of mucous membrane symptoms, age, gender and allergy. In the intervention group the offices were thoroughly cleaned, including removal of mineral fibre mats from the ceiling. The placebo group received only a quick, superficial cleaning of the office. Dust concentration and health indicators were measured before and after intervention or placebo treatment.
The dust level was reduced near the VDU after the intervention, and the reduction was statistically significant for offices with a high dust concentration before cleaning. A mucous membrane symptoms index score was reduced in the intervention group, compared to placebo (p<0.05). Among those participants with a narrow nasal airway, there was a larger increase in nasal volume 22-52 mm from the nasal orifice in the intervention group as compared to placebo. This effect was most pronounced among persons younger than 40 years and among participants with a history of rhinitis or asthma.
The third intervention investigates health improvements after removal of airborne dust using electrostatic filter units. Both upper and lower airways symptoms and function has been investigated. The project was implemented in early 1999. Results will be presented at the conference.
Two intervention studies on the physical environment of VDU users have been performed. In the first study we found that a reduction of the static electric field around the VDU prevented skin symptoms. In the second study an intensive cleaning of the office reduced the airborne dust, and upper airways symptoms and nasal congestion were reduced. These interventions indicate that dust and static electric fields should be given attention when the work environment for VDU users is evaluated. A third intervention testing the effect of air cleaning is carried out in 1999.
Andersson L, Bakke JV, Bjorseth O, Bornehag C-G, Clausen G, Hongslo JK et al. ( 1997). TVOC and health in non-industrial indoor environments. Report