Exposure extent

Acetate and triacetate are essentially unaffected by dilute solutions of weak acids, but strong mineral acids cause serious degradation. The results of exposure of heat-treated and untreated triacetate taffeta fabrics to various chemical reagents have been reported (9). Acetate and triacetate fibers are not affected by the perchloroethylene dry-cleaning solutions normally used in the United States and Canada. Trichloroethylene, employed to a limited extent in the UK and Europe, softens triacetate. 

In all of the process operations except venting and flaring, exposure is related to worker activity, and to some extent is dependent on worker behavior and the work practices appHed. The distinction between those exposures that are impacted by worker behavior and those that, barring the use of respirators, are not is important. The types of control methods to be appHed and the methods of exposure measurement to be used are influenced by this difference. 

Intrusiveness. Workers are likely to alter their behavior, consciously or unconsciously, when they are observed. To the extent that a worker s exposure is related to the worker s actions, this change can distort the representativeness of the evaluation. Measurement methods which require the close presence of the person collecting the sample are more likely to influence the result than samples collected with unobtmsive devices worn by the worker. 

Conclusion. The quantitative measurements, their interpretation, the calculated statistics, and the exposure criteria all come together to arrive at a conclusion to be drawn with a known chance of being wrong. The data and their interpretation give the extent of the conclusion. The exposure criteria, its origin and basis, define the impact of a conclusion that conditions are unsafe. 

Whereas the eadiest fluorescent-dye pigments would last only 20 days outdoors in a screen-ink film, fade resistance has been improved to such an extent that some modem daylight-fluorescent coated panels stiU have useful color after nine months or mote in Florida sunlight in a 45° exposure tack facing south. The fluorescent layer is usually coated with an acrylic film containing a uv absorber. Indoor-accelerated exposure equipment is, of course, invaluable in the development of such systems. Better dyes and resins very likely will make possible fat mote stable coatings in the future. 

Desflurane is less potent than the other fluorinated anesthetics having MAC values of 5.7 to 8.9% in animals (76,85), and 6% to 7.25% in surgical patients. The respiratory effects are similar to isoflurane. Heart rate is somewhat increased and blood pressure decreased with increasing concentrations. Cardiac output remains fairly stable. Desflurane does not sensitize the myocardium to epinephrine relative to isoflurane (86). EEG effects are similar to isoflurane and muscle relaxation is satisfactory (87). Desflurane is not metabolized to any significant extent (88,89) as levels of fluoride ion in the semm and urine are not increased even after prolonged exposure. Desflurane appears to offer advantages over sevoflurane and other inhaled anesthetics because of its limited solubiHty in blood and other tissues. It is the least metabolized of current agents. 

Health nd Safety Factors. Thionyl chloride is a reactive acid chloride which can cause severe bums to the skin and eyes and acute respiratory tract injury upon vapor inhalation. The hydrolysis products, ie, hydrogen chloride and sulfur dioxide, are beheved to be the primary irritants. Depending on the extent of inhalation exposure, symptoms can range from coughing to pulmonary edema (182). The LC q (rat, inhalation) is 500 ppm (1 h), the DOT label is Corrosive, Poison, and the OSHA PEL is 1 ppm (183). The safety aspects of lithium batteries (qv) containing thionyl chloride have been reviewed (184,185). 

Free formaldehyde is a mixture of formaldehyde, formaldehyde hydrates, and low molecular oligomers. It imparts a characteristic odor to padding bath or padded fabrics (76,77). CeUulosics fabrics are capable of retaining large quantities of free formaldehyde, which are gradually evolved. Because all finishes degrade to some extent, extractable formaldehyde and releasable formaldehyde must be considered with respect to user exposure. 

Dose—response evaluation is used in describing the quantitative relationship between the amount of exposure to a substance and the extent of toxic injury or disease. Data may be derived from animal studies or from studies in exposed human populations. Dose—response toxicity relationship for a substance varies under different exposure conditions. The risk of a substance can not be ascertained with any degree of confidence unless... 

Higher temperatures result in permanent degradation. The amount of this irreversible loss in mechanical properties depends upon moisture content, heating medium, temperature, exposure period, and, to some extent, species. The effects of these factors on modulus of mpture, modulus of elasticity, and work to maximum load are illustrated in Figures 6—9 (6). The effects may be less severe for commercial lumber than for clear wood heated in air (Fig. 10). The permanent property losses shown are based on tests conducted after specimens were cooled to - 24° C and conditioned to a moisture content of... 

Carbon tetrachloride is toxic by inhalation of its vapor and oral intake of the Hquid. Inhalation of the vapor constitutes the principal ha2ard. Exposure to excessive levels of vapor is characterized by two types of response an anesthetic effect similar to that caused by compounds such as diethyl ether and chloroform and organic injury to the tissues of certain organs, in particular the Hver and kidneys. This type of injury may not become evident until 1—10 days after exposure. The nature of the effect is deterrnined largely by the vapor concentration but the extent or severity of the effect is deterrnined principaHy by the duration of exposure (38). 

Insoluble corrosion prodiic ts may be completely impeivious to the corroding liquid and, therefore, completely protective or they may be quite permeable and allow local or general corrosion to proceed unhindered. Films that are nonuniform or discontinuous may tend to localize corrosion in particular areas or to induce accelerated corrosion at certain points by initiating electrolytic effects of the concentration-cell type. Films may tend to retain or absorb moisture and thus, by delaying the time of drying, increase the extent of corrosion resulting from exposure to the atmosphere or to corrosive vapors. 

Method used to clean specimens after exposure and the extent of any error expected by this treatment... 

As discussed in Sections 17.5 and 23.5.1, an electrical network may be exposed to different voltages surges which may be internal or external. The extent of exposure of the connected equipment would determine its level of insulation. lEC 60071-1 has recommended the desired... 

Installations that are electrically exposed to lightning are assigned the impulse voltages as in lists II or III of Table 13.2 or list II of Table 13.3, depending upon the extent of their exposure to lightning and the method of their neutral grounding. 

More than one lightning impulse insulation level is indicative of the extent of exposure of equipment to lightning surges. Correspondingly the power frequency withstand voltage can also be more than one. 

Equipment may be designed for more than one BIL values as noted in the various tables referred to above for motors, switchgears and other equipment. The choice of BIL for equipment for a paniciilai application will depend upon the extent of exposure the equipment may be subject to in normal service and the security level required by the system and the surge protection. For more details refer to Section 13.4.1(3). 

The power frequency voJiage lest refers to indoor units. The outdoor eapaciior units must be subjected to a wet test as in lEC 60060-1.. 3 The choice between list I and list 2 will depend upon the extent of exposure of the units to the internal and external vollage surges and... 

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