Reduced ventilation and infiltration, and new materials and machines have increased levels of indoor contaminants. Investigations of many indoor environments reveal contaminant levels above those set as standards for the workplace environments. The acute and chronic health effects on the population are not well known. This paper discusses the current general status of the research in the USA and the planned future effort. Worldwide research is also summarized and future directions are suggested.

Specific indoor air quality issues that have arisen in the UK in recent years have involved asbestos, formaldehyde, pesticide residues, radon and combustion products. Different measures have been taken with regard to each of these substances. In general, an education approach has been adopted, although national standards, industry self-regulation and some regulatory measures have been used. In the UK, control of ill defined, distributed or non stationary indoor air pollutants such as body odour, tobacco smoke and water vapour, is considered to be best achieved by suitable ventilation.

Summarizes the state of knowledge about combustion products, surface condensation and mould, formaldehyde and radon, and the guidance currently offered on their control in the UK. Statutory ventilation requirements are outlined and various measurement techniques described.

This paper presents a quantitative estimate of the error of the decay and constant concentration method. A number of tests were carried out in an indoor test house located in the laboratory hall at the National Swedish Institute for Building Research. The relevant meaning of the concept of air-exchange rate is discussed and an appropriate terminology is suggested. The theoretical background, based on a multi-cell model, of the two tracer gas methods is given.

Most houses in the Netherlands are equipped with gas-fired heaters and cooking appliances, since large amounts of natural gas are available. Carbon monoxide poisonings occasionally occur due to the use of instantaneous water heaters (geisers) that are gas fired. An investigation was carried out to establish the carbon monoxide production potential of geisers under normal conditions of use. The study involved 254 houses: the results indicated that 17% of the geisers produced a carbon monoxide level of more than 50 microL/L in thekitchens where they were located, after 15 min of operation.

The influence of the various sources of pollution on the home environment in the Netherlands is reviewed, eg, outdoor air, gas-fired appliances, tobacco smoking and building materials. The pollutants carbon monoxide, nitrogen dioxide, particles and radon are discussed in more detail. Available data show that outdoor standards for air quality are often exceeded indoors. However, conclusions on exposure and health effects cannot be drawn until more data are available from random or stratified samples of houses.

Presents a detailed description of the measurement technique and apparatus used to measure the air change rate in the Spencer St and Linford low-energy houses in Milton Keynes, UK. An automatic air infiltration rig using nitrous oxide tracer gas constant decay was used. Air leakage was also measured by pressurization for the Linford houses and some from the neighbouring Pennyland project.

This paper reviews the work carried out in the Netherlands on moisture problems. In current air flow simulation models for buildings, moisture transfer and diffusion in and between rooms are not taken into account. The aim of the research project is the development of an integral hygrothermal model in which the above mentioned aspects are incorporated.

Over the last few years frequent cases of mould growth in dwellings have occurred. The problem is essentially due to an excessive moisture content of the building elements, which can result from hygroscopic adsorption or from frequent surface condensation.

Surface condensation and mould affect about 15% of the UK housing stock. This paper reports BRE work undertaken in occupied dwellings to identify the effectiveness of a range of remedial measures in various situations. The remedies investigated include the improvements to insulation levels, andheating systems, the provision of extract fans and dehumidifiers. The studies were undertaken in both flats and 2-storey houses, all of traditional construction with brick walls and pitched roofs.