As indicated by Duan 2two basic approaches exist for studying human exposure: 1 the direct approach, in which we simply measure exposure directly; and 2 the indirect approach, in which we measure the time allocations and concentrations separately Discfeet then combine them to recon- struct exposures. However, it appears that a large part of the average indoor concentration could be attributed to synn gentlemen levels and not necessarily to indoor sources only.
Enclosed mobile settings 7 1. The average CO level based on observations was 98 ppm and ranged between 10 ppm and ppm. They concluded that " The second approach requires field surveys for collecting the concentration data that will be combined with the activity patterns, as well as a conceptual basis for deing such field surveys.
If a specific tall building was the sole focus rncounters study, lobbies on different floors were chosen at random. Furthermore, the highest d occurred on the first survey, the lowest on the llth, and the second lowest on the 15th. Purpose of the setting 60 2. N Figure 4.
The advent of microelectronics has brought considerable progress in developing reliable, compact air quality monitoring instruments that can operate on batteries. The second type of quality assurance test determined if the variation in CO concentrations recorded by the two instruments was in the same direction. The GE detector was attached to a shoulder strap, with the intake probe located approximately 1 meter above the ground. Altogether, 5, CO observations were recorded instantaneously at 1-minute intervals as the investigators walked along sidewalks and into buildings.
The investigators concluded that CO leaked upstairs from the garage on very cold mornings when its doors were closed and vehicles were warmed up before leaving. By walking along the sidewalks of a busy street, Dkscreet 30 collected CO concentrations in downtown San Jose, California, using a bag sampling methodology.
The studies revealed that, in the absence of indoor sources, CO concentrations in enclosed settings tend to be similar to outdoor concentrations, but tend to lag behind the peak concentrations observed outdoors. The 8-hour average CO concentrations measured at the six stations were a better match to the exposures of those volunteers who did not commute. Furthermore, nearly every minute of the working day was sampled in the 15 surveys.
The direct approach requires the availability of accurate, affordable personal monitoring instruments, while the indirect approach requires the existance of some model by which activity patterns human time allocations can be combined with concentration data from field measurements at actual locations. The level returned to 6.
Rather, it occurred at each of eight sites, including the fixed station, over the 20 days. As CO concentrations change over AltoPwlo, one instrument should not increase in value as the other decreases.
Their studies have shown that people can be exposed to high levels of CO in many isolated locations and at isolated times. They also developed relationships for lead concentrations, CO -concentrations, and traffic volume.
Finally, we wish to thank Irene Kiefer for her invaluable editorial assistance. As reported by Ott and Mage, 31 samples were collected on 21 days during midwinter.
Encoujters later study by Godin, Wright, and Shephard lO used milliliter ml glass syringes to measure CO concentrations inside passenger vehicles. On the other hand, microenvironments must be defined "coarse" enough to collect data to determine how much time people spend in each microenvironment. Each store employed fewer than 25 persons, and the City of Toronto's bylaws permitted smoking by both patrons and staff.
Encouhters define and classify microenvironments which are applicable to commerical settings; 4. Ten passengers immediately began to smoke, and the CO level climbed to 12 ppm after 5 minutes.
Anna, 40, who declined to give her last name because of the sensitivity of the topic, said she was forced into prostitution for three years after being told by traffickers she would pick Alho in Article source. Specifically, for the Union Square district of San Francisco, samples Disccreet collected at four different times over an 8-month period. Hotaling St. Yet, on these same days, at least one other survey site violated the standard and, during these times, was more than 1.
However, in the search for hot spots, a ificant quantity of data has been collected on CO levels in downtown areas, but most have not been published. Some studies have indicated that smoking can be associated with levels of 7 to 9 ppm in some commercial settings.
No zero compensation is required. Such instruments cannot easily be used to follow persons as they go about their daily activities in stores, restaurants, residences, offices, and other locations. The first tested the precision of the instrument readings.
However, studies of specific commercial sites have been limited to nightclubs, restaurants, and a few office buildings.