in this survey, asbestos fiber levels within the breathing zone of employers and in the environment of an asbestos-cement factory were monitored on membrane filter and counted by phase contrast optical microscope considering length/diameter>3:i (asbestos international associational method). the plant was fairly old and utilized both white (chrysotile) and blue (chrocidolite) asbestos. in each w...

vehicle exhaust is a major source of exposure to polycyclic aromatic hydrocarbons (pahs) found in the urban atmosphere. newsagents usually work close to heavy traffic flow. the purpose of this study was to assess the breathing zone exposure of newsagents to pahs found in the urban atmosphere of tehran city during summer and autumn seasons and comparing the levels of exposure in both seasons.fif...

Background: Volatile organic compounds (VOCs), including carcinogens and toxic compounds, are produced in petrochemical industries. We undertook this study in order to study workers’ respiratory exposure to different VOC concentrations and compare the results with the urinary levels of its metabolites and study the correlation between them in petrochemical industries. Materials and Met...

BACKGROUND Floor dust is commonly used for microbial determinations in epidemiological studies to estimate early-life indoor microbial exposures. Resuspension of floor dust and its impact on infant microbial exposure is, however, little explored. The aim of our study was to investigate how floor dust resuspension induced by an infant's crawling motion and an adult walking affects infant inhalat...

Activity based sampling (ABS) is typically performed to assess inhalation exposure to particulate contaminants known to have low, heterogeneous concentrations on a surface. Activity based sampling determines the contaminant concentration in a person's breathing zone as they perform a scripted activity, such as raking a specified area of soil, while wearing appropriate sample collection instrume...

background: volatile organic compounds (vocs), including carcinogens and toxic compounds, are produced in petrochemical industries. we undertook this study in order to study workers’ respiratory exposure to different voc concentrations and compare the results with the urinary levels of its metabolites and study the correlation between them in petrochemical industries. materials and methods: exp...

UNLABELLED Using computational fluid dynamics simulations of an occupant in a ventilated room, we find that breathing zone ozone levels can be substantially lower and ozone reaction products associated with human surfaces (ORPHS) levels considerably higher than room levels. For air exchange rates <3/h, the ratio of the breathing zone to the ozone concentration 1 m from the body (bulk air), r(oz...

Conventionally, the "breathing zone" is defined as the zone within a 0.3 m (or 10 inches) radius of a worker's nose and mouth, and it has been generally assumed that a contaminant in the breathing zone is homogeneous and its concentration is equivalent to the concentration inhaled by the worker. However, several studies have mentioned that the concentration is not uniform in the breathing zone ...