Detailed radon measurements and ventilation testing were carried out in five residential premises in Hong Kong. Continuous radon detectors were located in the bedrooms of each site and corresponding C02 decay tests were conducted to estimate the ventilation rate. Four air-conditioning operation modes were used in the measurements. Data obtained from the measurements were used to verify the validity of a simple mass balance model.

A study of air movement and aerosol particle distribution and migration in a ventilated two-zone chamber is presented. The comparisons of average particle concentration decay between numerical results and measured data are generally satisfactory and acceptable. It can be concluded that the particle distribution and migration are mainly influenced by the airflow pattern and ventilation rates.

Builders are never rnore surprised than when they walk into one of their newly built model homes and find black stains at wall-to-floor joints and on previously pristine carpeting underneath doorways. What causes these stains and how can builders and homeowners prevent them?