Number Concentrations and Modal Structure of Indoor/Outdoor Fine Particles in Four European Cities

Abstract

Indoor/outdoor aerosol size distribution was measured in four European cities (Oslo-Norway, Prague-Czech Republic, Milan-Italy and Athens-Greece) during 2002 in order to examine the differences in the characteristics of the indoor/outdoor modal structure and to evaluate the effect of indoor sources to the aerosol size distributions. All the measurement sites were naturally ventilated and were occupied during the campaigns by permanent residents or for certain time periods by the technical staff responsible for the instrumentation. Outdoor particle number (PN) concentrations presented the higher values in Milan and Athens (median values 1.4 × 10 4 # cm -3 and 2.9 × 10 4 # cm -3 respectively) as a result of elevated outdoor emissions and led to correspondingly higher indoor values compared to Oslo and Prague. In absence of indoor activities, the indoor concentrations followed the fluctuations of the outdoor concentrations in all the measurement sites. Indoor activities (cooking, smoking, etc.) resulted in elevated indoor PN concentrations (maximum values ranging between 1.7 × 10 5 # cm -3 and 3.2 × 10 5 # cm -3 ) and to I/O ratios higher than one. The I/O ratios were size dependant and for periods without indoor activities, they presented the lowest values for particles < 50 nm (0.51 ± 0.15) and the ratios increased with fine particle size (0.79 ± 0.12 for particles between 100-200 nm). The analysis of the modal structure showed that the indoor aerosol size distribution characteristics differ from the outdoors under the effect of indoor sources. The percentage of unimodal size distributions increased during indoor emissions, compared to periods without indoor sources, along with the number concentration of Aitken mode particles, indicating emissions in specific size ranges according to the type of the indoor source.

Fine and ultrafine particle removal efficiency of new residential HVAC filters

“…Google Scholar was used to search for the following terms: indoor concentration, particle size distribution, particle size characterization, SMPS, ultrafine particle emissions, and fine particle emissions. Sixteen studies reporting a total of 201 PSDs were selected for analysis through this procedure . Most of these studies (a) occurred in various European cities (with a few in the United States and Asia), (b) measured size‐resolved particle number concentrations in the range of 10 nm to 1000 nm, and (c) reported their results graphically in terms of dN/dlog D p versus the log of particle size, D p .…”

“…Sixteen studies reporting a total of 201 PSDs were selected for analysis through this procedure. [59][60][61][62][63][64][65][66][67][68][69][70][71][72][73][74] Most of these studies (a) occurred in various European cities (with a few in the United States and Asia), (b) measured size-resolved particle number concentrations in the range of 10 nm to 1000 nm, and (c) reported their results graphically in terms of dN/dlogD p versus the log of particle size, D p .…”

Indoor Particle Concentrations, Size Distributions, and Exposures in Middle Eastern Microenvironments

“…It is very well documented in the literature that the temporal variation in indoor aerosol concentrations closely follows those outdoors in the absence of indoor activities [20,30,32,[63][64][65][66][67][68][69][70][71][72][73][74]. As such, the aerosol indoor-to-outdoor relationship depends on the size-resolved particle penetration factor for the building envelope, the ventilation and infiltration rates, and the size-resolved deposition rate onto available indoor surfaces [20,30,64].…”

Design and Performance Evaluation of a PN1 Sensor for Real-Time Measurement of Indoor Aerosol Size Distribution

“…Nonetheless, our PN 1 sensor can be used for monitoring indoor particle size distribution in cases of high indoor emission source and indoor activity. According to Lazaridis et al (2017), who measured indoor and outdoor aerosol size distributions in four European cities during 2002 and evaluated the effect of indoor sources on the aerosol size distribution, the percentage of unimodal size distribution increases during indoor emissions, indicating the presence of particles in specific size ranges according to the indoor activity and usually overlapping the multimodal structure of the background aerosol.…”