ECA 25: Strategies to determine and control the contributions of indoor air pollution to total inhalation exposure (STRATEX)

Human exposure to environmental pollutants occurs via various pathways such as air, drinking water, food, and dermal contact. For many pollutants, especially the volatile ones, air exposure is the dominant pathway. Exposure via air occurs both outdoors and indoors, with diverse types of indoor spaces playing a role, e.g., home, workplace, schools, kindergartens, and passenger cabins of means of transportation.
 
It is now well established that indoor air pollution contributes significantly to the global burden of disease of the population. Therefore, the knowledge of this contribution is essential in view of risk assessment and management. In principle, the characterisation of population exposure to indoor air pollution can be achieved by issue focussed small-scale studies at local level or large-scale population studies. If the small-scale study approach is selected then ways should be established to extrapolate from these to the general population. As large-scale surveys are normally designed to be representative their results are directly reflecting population exposure. However, large-scale surveys are expensive, time and labour intensive so that often modelling exercises are adopted to characterise and quantify population exposure to indoor air pollution. Under some circumstances the measurement strategy cannot be followed, and a modelling strategy will have to be adopted. To do this, a number of other pieces of information need to be known and considered.Among these are, e.g., the behaviour of people (time-activity patterns), the determinants of indoor air quality (sources and their emissions and sinks), and the building characteristics.
 
This report collates the respective information and describes the strategies to determine population exposure to indoor air pollutants. Its major goal is to emphasise the importance of the contribution of indoor air to total air exposure. Taking this contribution into account is a prerequisite for sound risk assessment of air pollution.
 
The strategies described should be considered as a framework.This framework may have to be adapted to specific situations by policy makers, risk assessors, and risk managers.