Recommended limit value

The basic philosophy has been to standardize evaluation methods, with recommended limit values for the different parameters or indices listed in informative annexes. These or other values may then be adapted in national rules for the thermal environment. 

Exposure to silica, as you might imagine, is considered to have a high hazard potential. The recommended limiting value for cristobalite as a total mass in the breathing air, for example, is 0.15 milligrams per cubic meter of air. 

Occupational exposure limit values. Ingredients with an occupational exposure limit value (OEL), mentioned in heading 1, have to be listed. Primarily, the mandatory national hmit values have to be specified, followed by additional recommended limit values. 

Table 7.10 Recommended limiting values for evaluation of rut resistance performance ...

The recommended limiting values set for all the above parameters are as shown in Table 7.10. The above parameters/criteria are used at the mix design stage for the determination of the target mix or for the evaluation of its conformity to the declared value by the producer. 

This work allowed to expand the knowledge in this topic and is expected to have made a useful contribution to other similar situations. Evaluating WBV in urban bus drivers with both ISO standards, allowed a more complete assessment of working conditions. It was clear that the WBV exposures in this sample of urban bus drivers, do not exceed the recommended limit values. The seats are also doing its role reducing the transmission of the WBV to the drivers in all the cases. The constant adoption of preventive measurements is recommended, as well as the preoccupation about pavements improvement. In the future, this research may be consolidated starting from the limitations identified. 

If acetal resins are processed at temperatures substantially above those recommended for the particular grade, minor amounts of formaldehyde may be Hberated. Formaldehyde (qv) is a colorless, lacrimatory gas with a pungent odor and is intensely irritating to mucous membranes. The human nose is sensitive to concentrations in the range of 0.1 to 0.5 ppm. The current threshold limit value for formaldehyde is 1 ppm. 

To efficiendy drive the development of improved substrate materials, the limiting values of birefringence have to be known this is especially tme for WORM and EOD(MOR) substrate disks. These limit values were laid down by the ANSI (American National Standard Institute) Technical Standard Committee (186—188). For 5.25 in. WORM disks, the ANSI document X 3 B 11/88-144 recommends a maximum LEP value of 9% this corresponds to an optical path difference perpendicular to the plane of the disk of not more than 80 nm/mm (double path). For 5.25 in. EOD(MOR) disks, more stringent conditions apply (ANSI-document X 3 B 11/88-049), which also allow calculation of the allowed range. 

Magnesium vanadates, as vanadium compounds in general, are known irritants of the respiratory tract and conjunctiva. The threshold limit value (TLV) for vanadium compounds in air recommended by the National Institute of Occupational Safety and Health is 0.05 mg/m based on a typical 8-h workday and 40-h workweek (7,147). Chronic inhalation can lead to lung diseases such as bronchitis, bronchopneumonia, and lobar pneumonia. These dust-related effects can be avoided by use of individual respirators in areas where exposure is likely. 

The 1994—1995 threshold limit values as recommended by the American Conference of Governmental Industrial Hygienists (ACGIH) are given in Table 8. These time-weighted average values are those levels to which nearly all workers may be exposed for an 8-h workday and a 40-h work week without adverse effect (99). 

Current OSHA standards specify the threshold limit value (TLV) 8-h exposure to ammonia as 50 ppm (35 mg/m ). However, the ACGIH recommends a TLV of 25 ppm (96). Respiratory protection should be provided for workers exposed to ammonia. Protective clothing such as mbber aprons, boots, gloves, and goggles should be worn when handling ammonia. 

AH volatile organic solvents are toxic to some degree. Excessive vapor inhalation of the volatile chloriaated solveats, and the central nervous system depression that results, is the greatest hazard for iadustrial use of these solvents. Proper protective equipment and operating procedures permit safe use of solvents such as methylene chloride, 1,1,1-trichloroethane, trichloroethylene, and tetrachloroethylene ia both cold and hot metal-cleaning operations. The toxicity of a solvent cannot be predicted from its chlorine content or chemical stmcture. For example, 1,1,1-trichloroethane is one of the least toxic metal-cleaning solvents and has a recommended threshold limit value (TLV) of 350 ppm. However, the 1,1,2-trichloroethane isomer is one of the more toxic chloriaated hydrocarboas, with a TLV of only 10 ppm. 

Recommendations by the ACGIH are classified as threshold limit values (TLV) based on 8-h TWA. Chromium metal and alloys, Cr(II) compounds and Cr(III) compounds, including chromite ore, have a TLV of 0.5 mg/m Cr in air. Water-soluble Cr(VI) compounds have a TLV of 0.05 mg/m Cr. Certain water-insoluble Cr(VI) compounds, ie, the chromates of 2inc, barium, calcium, lead, strontium, sintered chromic acid, and processing chromite ores, also have a TLV of 0.05 mg/m as well as a human carcinogen designation (145). 

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