title: Particle concentration profile in a vertical displacement flow: a study in an industrial hall.
abstract: The effect of displacement flow on the distribution of aerosol concentration was investigated in an industrial hall. According to the displacement ventilation principle, vertical upflow is accomplished by introducing fresh air, cooler than room air, into the occupied zone near floor level. The fresh air is introduced from low-velocity devices and heated by warm processes. This technique allows warm air contaminants to rise to the ceiling, and the rising plume is then exhausted close to the ceiling. This study presents the results of a field study conducted in an industrial environment. The aerosol properties and behavior, especially the vertical gradients, are characterized in a displacement flow field. The results indicate that the fine particles, less than 1 microm in diameter, are transported away from the breathing zone by the ventilation process. However, the air quality is significantly influenced by the emission source, and therefore the number concentration of fine and ultrafine (smaller than 0.1 microm in diameter) aerosol particles in the breathing zone was clearly elevated compared to that of the incoming clean air. The vertical gradients displayed clear size dependence; the strongest gradients were found for particles between 0.003 and 0.015 microm in diameter.
authors.affiliation: Finnish Institute of Occupational Health, Helsinki, Finland.
authors.forename: Kaarle
authors.initials: K
authors.lastname: Hämeri
authors.forename: Anca
authors.initials: A
authors.lastname: Gaman
authors.forename: Tareq
authors.initials: T
authors.lastname: Hussein
authors.forename: Jouni
authors.initials: J
authors.lastname: Räisänen
authors.forename: Raimo
authors.initials: R
authors.lastname: Niemelä
authors.forename: Pasi P
authors.initials: PP
authors.lastname: Aalto
authors.forename: Markku
authors.initials: M
authors.lastname: Kulmala
mesh_terms: D000336:Aerosols / Q000032:analysis*; D000397:Air Pollution / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D006813:Humidity; D007221:Industry; D016273:Occupational Exposure / Q000032:analysis*; D010316:Particle Size; D013696:Temperature; D017132:Workplace
chemical_list: D000336:Aerosols