Perceived Particle Intensity: An Indicator to Evaluate Indoor Particle Pollution

Abstract

Suspended particles have recently received much interest in research circles because of increasing epidemiological and experimental evidence of their potential health impacts. Based on the concept of health risk assessment, this paper proposes an indicator called perceived particle intensity (PPI) to evaluate indoor particle pollution as an improvement on the currently used index. In view of the uncertainty regarding any biological mechanism as to how particles cause harm to human health, the amount of particle deposition is assumed here for simplicity to be a criterion for risk assessment and the fractional deposition is calculated according to ICRP 66. The case of a classroom is presented to illustrate the practical application of PPI and the numerical method adopted to simulate the spatial distribution of particles. The results show that exposure to particles and perhaps the consequent health risk vary greatly among the students in the room. This occupant-oriented indicator considers more factors, including those of microenvironments as well as human beings, e.g. gender, age, health conditions, activity type, etc. It is expected that this improved concept will be helpful in directing ventilation system design and evaluating the impact of indoor particulate pollution more reasonably.