Personal exposure monitoring

As well as direct-reading tubes for short-term measurements, tubes are also available for long-term monitoring. Here, the air sample is sucked through the tube by use of a personal-air-sampling pump (PAS-pump). These all look more or less the same and have a similar kind of indication to that of short-term tubes.Their area of application corresponds to that of PAS procedures (see Section 6.9.1.4.1). In contrast to these, the concentration can be read directly at the end of monitoring. Personal exposure is calculated based on the air volume pulled through. 

In general practice, gas detection instruments working with electrochemical sensors are very commonly employed. These rather compact devices can be worn on the body, and therefore they are very suitable for monitoring personal exposure. The user is alerted in the case of hazardous concentrations in the working environment by an audible and visible alarm device. Usually, the instruments include a data logger, which enables the recorded data to be evaluated at a PC at a later point of time. The necessary software is normally supphed with the device. 

A record should be kept of any monitoring for at least 5 years, unless it is representative of personal exposure of identifiable employees when records must be retained for at least 40 years. 

Trichloroethylene levels monitored in expired breath of 190 New Jersey residents were correlated with personal exposure levels, which were consistently higher than outdoor air levels and were instead attributed to indoor air levels (Wallace et al. 1985). Other studies have expanded upon and confirmed these findings, concluding that indoor air is a more significant exposure source of trichloroethylene than outdoor air, even near major point sources such as chemical plants (Wallace 1986 Wallace et al. 1986a, 1986b, 1986c,... 

This is a temporal study of personal exposures to particulate matter in a panel of patients with chronic obstructive pulmonary disease. Fifteen subjects will be monitored... 

Relationship Between Personal, Outdoor and Indoor Air Concentrations (RIOPA) The overall goal of the national multicenter (Elizabeth, NJ, Houston, TX, and Los Angeles County, CA) RIOPA study is to establish a scientific foundation for effective, timely, public health intervention strategies. Outdoor, indoor, and personal exposures of adults and children to PM are measured and evaluated by mass, elemental, chemical, and source apportionment analyses in the other research programs. Non-smoking asthmatic and non-asthmatic adults and their children are included. Monitoring occurs... 

Michael LC, Pellizzari ED, Perritt RL, et al. 1990. Comparison of indoor, backyard, and centralized air monitoring strategies for assessing personal exposure to volatile organic compounds. Environmental Science and Technology 24 996-1003. 

FIGURE 15.15 Geometric mean PM1(I concentrations outdoors, indoors, and by personal exposure monitors during the day and at night in Riverside, California, weighted to provide estimates of concentrations for household-days or person-days. The error bars are 90th percentile (data from Clayton et at., 1993). 

The EPA has conducted four major studies of actual human exposure using monitors worn by random samples of people. The results are shocking. Smoking, clothes that had been dry cleaned and hung in closets, and heated water in showers and clothes washers (i.e., chloroform from chlorinated water) are major sources of human exposure to volatile organic compounds (VOCs), all of which exceeded outdoor exposure sources by two to five times at the median exposure level. The major sources of exposure to another VOC, p-dichlorobenzene, are toilet fresheners and mothballs. Pesticide exposure stems from two main sources (1) vapors emitted by soil into homes through basements and (2) soil tracked into buildings on shoes. Major stationary and mobile sources account for only 2 to 25 percent of personal exposure to the two dozen or so VOCs and pesticides that the EPA studied (Wallace 1993, 138 Ott and Roberts 1998). 

West, P. W., "Passive Monitoring of Personal Exposures to Gaseous Toxins," Amer. Lab., July 1980, p. 35. 

Recent years have seen advances in collection and analytical methods to determine contaminant concentrations in the air. One of these innovations involves the sampling of Organic Vapors without the use of mechanical air pumps in particular the monitoring of personal exposures. 

A second product, the Organic Vapor Monitor, was introduced to the market in January of 1978. An additional patent on personal exposure monitoring was issued in July of 1978. 

Of course, on considering personal exposure monitoring by any method, it is helpful to have a point or frame of reference. In this case, that point of reference is the established pump and tube method. It features a mechanical pump whose function is to draw a constant, measured flow of an air-vapor mixture through a tube, normally consisting of two sections, where the vapors are selectively adsorbed. 

The theory and practical use of a diffusional monitor is described. The diffusional monitor can be used to accurately measure personal exposures, as well as to determine area concentrations of organic vapors. 

Exposure studies can be carried out aiming to estimate exposure of one individual (personal exposure) or of a larger population group (population exposure), through direct or indirect methods. Direct methods are measurements made by personal portable exposure monitors. The personal exposure monitoring devices that people carry with them must be lightweight, silent, highly autonomous and... 

These small, flexible devices open up two new monitoring paradigms (1) personal exposure and mobile monitoring and (2) measurements at a multitude of fixed sites which can also be flexibly located in living areas where current monitoring containers cannot be placed. 

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