To investigate the effect of ventilation on indoor radon (222Rn), simultaneous measurements of radon concentrations and air change rates were made in 117 Danish naturally ventilated slab-on-grade houses built during the period 1984-1989. Radon measurements (based on CR-39 alpha-track detectors) and air change rate measurements (based on the perfluorocarbon tracer technique; PFT) were in the ranges 12-620 Bq m-3 and 0.16--0.96 h-1, respectively. Estimates of radon entry rates on the basis of such time-averaged results are presented and the associated uncertainty is discussed.

An extensive survey has been carried out in 52 underground car parks in Hong Kong focusing on carbon monoxide concentrations in the air. So far as short term health effects are concerned this compound is generally regarded as the most important chemical species from car exhausts. Its presence can be used to quantify air pollution, and give an indicator of the air quality in car parks. The sites were sampled during peak hours. This report presents the results and analysis of the carbon monoxide levels measured.

A publicly-owned office building in Eskilstuna, Sweden, has been retrofitted with high-frequency with self-regulating controls for the lighting and ventilation systems. The building has a total floor area of 19,000 m2 and contains more than 3 00 offices, a conference room, lunch rooms, and a recreation hall. Before retrofitting the total annual electricity consumption was 1/300 MWh and the district(heat consumption was 950 MWh. The total annual energy consumption was reduced by 20% as a result of the new installlations.