TLV-STEL

Measures of inhalation toxicity include ERPG, TLV, TLV-STEL, TLV-TWA, PEL, and IDLH. 

TLV-STEL, THRESHOLD LIMIT VALUE - SHORT TERM EXPOSURE LIMIT (USa) A maxilHUm limit On the... 

TLV-STEL Threshold Limit Vahie-Short-Term Exposure Limit... 

With regard to limiting the concentration of particular contaminants, these are generally referred to in terms of threshold limit values (TLV), expressed either in terms of a time-weighted average (TLV - TWA) which represents the average concentration for a normal working day over a 40-hour week to which nearly all workers may be exposed on a repeated basis or as a short-term exposure limit (TLV - STEL), which represents the maximum... 

Threshold Limit Value - Short Term Exposure Limit (TLV-STEL). The maximum concentration to which workers can be exposed for a period of up to 15 minutes... 

There are three different types of TLVs (TLV-TWA, TLV-STEL, and TLV-C) with precise definitions provided in Table 2-7. More TLV-TWA data are available than TWA-STEL or TLV-C data. 

TLVs established by the ACGIH, including short-term exposure limits (TLV-STELs) and ceiling concentrations (TLV-Cs),... 

Certain (ACGIH) criteria may be appropriate for use as benchmarks. The ACGIH threshold limit values — TLV-STELs and TLV-Cs — are designed to protect workers from acute effects resulting from exposure to chemicals such effects include irritation and narcosis. These criteria are discussed in chapter 2. These criteria can be used for toxic gas dispersion but typically produce a conservative result because they are designed for worker exposures. 

The use of TLV-STELs and ceiling limits may be most appropriate if the objective is to identify effect zones in which the primary concerns include more transient effects, such as sensory irritation or odor perception. In general, persons located outside the zone that is based on these limits can be assumed to be unaffected by the release. 

The hazard endpoint time scale th describes the length of time required for the contaminant to pose a hazard. There are many different time scales associated with various toxicity levels (e.g., TLV-C ceiling limit values are never to be exceeded, TLV-STEL values are not to be exceeded in a 15-min period, etc.). Time scales associated with flammability hazards reflect the maximum local concentration (and also typically including peak-to-mean concentration ratios) and for reasons discussed above are considered representative of dispersion model averaging times of around 20 s. 

Threshold Limit Value Short-Term Exposure Limit (TLV-STEL) was also developed by ACGIH and represents the concentration to which workers can be exposed continuously for a short period of time without suffering from (1) irritation, (2) chronic or irreversible tissue damage, or (3) narcosis of sufficient degree to increase the likelihood of accidental injury, to impair self-rescue, or to materially reduce work efficiency and provided that the daily TLV-TWA is not exceeded. 

Threshold Limit Value Airborne concentrations of substances devised by the ACGIH that represent conditions under which it is believed that nearly all workers maybe exposed day after day with no adverse effect. TLV s are advisory exposure guidelines, not legal standards, based on evidence from industrial experience, animal studies, or human studies when they exist. There are three different types of TLV s Time Weighted Average (TLV-TWA) Short Term Exposure Limit (TLV-STEL) and Ceiling (TLV-C). (See also PEL)... 

The TLV is not a single entity. The ACGIH defines three categories of TLV, namely, the time-weighted average (TLV-TWA), the short-term exposure limit (TLV-STEL), and the ceiling. Because these are proprietary terms, the U.S. Occupational Safety and Health Administration (OSHA) has adopted different terminology for essentially the same concepts, as follows ... 

The 2003 ACGIH threshold limit value-time-weighted average (TLV-TWA) for benzene is 0.5 ppm (1.6mg/m ) with a TLV STEL of 2.5ppm (8mg/m ) and an Al-confirmed human carcinogen designation and a notation for skin absorption. 

The 2003 ACGIH threshold limit valuetime-weighted average (TLV-TWA) is 50 ppm (205 mg/m ) and the short-term excursion limit (TLV-STEL) is 100 ppm (410mg/m ) with a notation for sensitization. 

Benzene has a low threshold limit value or TLV. The time weighted average TLV (TWA) is the allowable exposure for an average 8 hr day or a 40 hr week. The short-term exposure limit TLV (STEL) is the maximum allowable exposure for any 15-min period. For benzene the TWA = 0.5 ppm and the STEL is 2.5 ppm, as given by the American Conference of Governmental Industrial Hygienists (ACGIH). This allowable exposure is much lower than those for toluene and xylene, probably because these latter two compounds have benzyl ic positions that are easily oxidized in vivo to compounds that can be eliminated from the body. 

Debate is continuing on the safety and toxicity of formaldehyde and its products, especially urea-formaldehyde foam used as insulation in construction and phenol-formaldehyde as a plywood adhesive. Presently the TLV-STEL of formaldehyde is 0.3 ppm. Formaldehyde is on the Reasonably Anticipated to Be Human Carcinogens list. 

Short-term exposure limit (TLV-STEL) designates permissible exposure for no more than 15 min, and no more than four times per day, with at least 60-min intervals between exposures. 

TLV The TLV or Threshold Limit Value refers to a safe level of exposure by inhalation. The definition was established by the American Conference of Governmental Hygienists. There are several variations or criteria levels for the TLV. As an example, hydrogen sulfide has a TLV for short-term exposure limits (STEL) of 15 minutes of only 5 ppm. Comparing this to the TLV-STEL of 400 ppm for carbon monoxide provides an indication of the need to be extremely careful when H2S is suspected. Under OSHA Standards, and particularly on MSDS (Material Safety Data Sheets) compounds are associated with a time weighted average (TWA) TLV, which is the allowable concentration for an 8-hour continuous exposure period. For firefighting purposes, the short-term exposure is likely more realistic. 

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