Threshold limit averages

Exposure limits (threshold limit value or TLV) are those set by the Occupational Safety and Health Administration and represent conditions to which most workers can be exposed without adverse effects. The TLV value is expressed as a time weighted average airborne concentration over a normal 8-hour workday and 40-hour workweek. 

American Conference of Government Industrial Hygienists (ACGIH) threshold limit value = 5 ppm on an 8-h time-weighted average. 

Threshold limit value, time-weighted average. 

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). 

Threshold limit value—time weighted average. Defined as the maximum time weighted average concentration to which a worker may be exposed repeatedly and without adverse effects for a normal 8 h/d, 40 h/wk period. 

Exposure to tantalum metal dust may cause eye injury and mucous-membrane irritation. The threshold limit value (TLV) in air is 5 mg/m, LD q is <400 mg/kg and the Occupational Safety and Health Administration (OSHA) time weighted average (TWA) exposure limit is 5 mg/m (47). The immediate dangerous to life or health (IDLH) concentration is 2500 mg/m (48). Whereas some skin injuries from tantalum have been reported, systemic industrial poisoning is apparently unknown (47). 

Because pulp bleaching agents are, for the most part, reactive oxidising agents, appropriate precautions must be taken in their handling and use. For example, it is important to ensure that the threshold limit values (TLV) (20) in Table 2 are not exceeded in the workplace air. These are airborne concentrations in either parts per million by volume under standard ambient conditions or mg per cubic meter of air. They "represent conditions under which it is beUeved that nearly all workers may be repeatedly exposed, day after day, without adverse effect" (20). TWA refers to a time-weighted average for an 8-h workday STEL is a short-term exposure limit or maximum allowable concentration to which workers can be continuously exposed for 15 minutes. 

The threshold limit value—time integrated average, TLV—TWA, of chlorine dioxide is 0.1 ppm, and the threshold limit value—short-term exposure limit, STEL, is 0.3 ppm or 0.9 mg /m of air concentration (87,88). Chlorine dioxide is a severe respiratory and eye irritant. Symptoms of exposure by inhalation include eye and throat irritation, headache, nausea, nasal discharge, coughing, wheezing, bronchitis, and delayed onset of pulmonary edema. Delayed deaths occurred in animals after exposure to 150—200 ppm for less than one hour. Rats repeatedly exposed to 10 ppm died after 10 to 13 days of exposure. Exposure of a worker to 19 ppm for an unspecified time was fatal. The ingested systemic effects of low concentration chlorine dioxide solutions are similar to that of chlorite. 

Inhalation. The threshold limit value of HCN is 4.7 ppm. This is defined as the maximum average safe exposure limit for a 15-min period by the Occupational Safety and Health Administration. Exposure to 20 ppm of HCN in air causes slight warning symptoms after several hours 50 ppm causes disturbances within an hour 100 ppm is dangerous for exposures of 30 to 60 min and 300 ppm can be rapidly fatal unless prompt, effective first aid is adininistered. There is always a small concentration of cyanide (0.02 to 0.04 mg/L) in the blood, and the body has a mechanism for continuous removal of small amounts, such as from smoking, by converting it to thiocyanate, which is discharged in the urine. 

The ACGIH threshold limit value (TLV), time-weighted average for an 8 hour workday, 40 hour workweek, was set at 50 ppm (- 200 mg/m ) with a notation for skin absorption (29). 

The time-weighted average OSHA permissible exposure limit (PEL), as weU as the ACGIH threshold limit value (TLV), for cyclohexanone is 25... 

Threshold limit value—time-weighted average. Intraperitoneal. 

TLV-TWA, THRESHOLD LIMIT VALUE - TIME WEIGHTED AVERAGE (USa) A limit fOf the atmOSpliei ic concentration of a chemical, averaged over an 8-hr day, to which it is believed that most people can be exposed without harm. 

This knowledge is also important in order to determine if air tests conducted by OSHA compliance officers are valid. For example, if threshold limit value in the health standard is an 8-hour time-weighted average, the air sample should be obtained by sampling over the entire shift in the employee s breathing zone. It cannot be measured by a few short term samples, even if spaced over the full shift unless the worker is in a relatively fixed location with no variation in his work procedure or in the process. Such an event is generally the exception rather than the rule. 

TLV-TWA Threshold Limit Vahie-Time-Weighted Average... 

Threshold Limit Value-Time Weighted Average (TLV-TWA) The time-weighted arerage concentration for a coinentioiial 8-hour workday and a 40-hour workweek, to which nearly all workers may be repeatedly exposed, day after day, without adverse effect,... 

Toxicity is referenced to the Threshold Limit Value — Time Weighted Average established for each refrigerant. This is defined in ASHRAE Standard 15-1994 as (refer to the manufacturer s product data for more complete detail) ... 

Class A signifies refrigerants for which toxicity has not been identified at concentrations less than or equal to 400 ppm, based on data used to determine Threshold Limit Value-Time Weighted Average (TLV-TWA) or consistent indices from Section 6.1.2. ... 

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