Characteristics of particle number and mass concentrations in residential houses in Brisbane, Australia

Abstract

Diurnal variation of indoor submicrometer (0.007–0.808 mm) particle number andparticle mass (approximation of PM2.5) concentrations was investigated in 15 houses in a residential suburb of Brisbane during winter in 1999. Continuous monitoring for more than 48 h was conducted using a condensation particle counter (CPC) and a photometer (DustTrak) in the kitchen of each house, and the residents kept diaries of the activities conducted. In addition, data from a central monitoring station was used to investigate indoor/outdoor relationships. The results show that there were clear diurnal variations in both particle number and approximation of PM2.5 concentrations, for all the investigatedhouses. The pattern of diurnal variations variedfrom house to house, however, there was always a close relationship between the concentration andhuman indoor activities. The average number and mass concentrations during indoor activities were (18.273.9)103 particles cm3 and(15.5 77.9) mgm3, respectively, andund er nonactivity conditions, (12.472.7)103 particles cm3 (11.172.6)7mgm3, respectively. In general, there was a poor correlation between mass andnumber concentrations and the correlation coefficients were highly variable from day to day and from house to house. This implies that conclusions cannot be drawn about either one of the number or mass concentration characteristics of indoor particles, based on measurement of the other. The study also showed that it is unlikely that particle concentrations indoors could be represented by measurements conducted at a fixed monitoring station due to the large impact of indoor and local sources.