Time-weighted average


Time-weighted exposure. This is the time-weighted average concentration for a normal 8-hour workday or 40-hour workweek to  [c.259]

Ozone s presence in the atmosphere (amounting to the equivalent of a layer 3 mm thick under ordinary pressures and temperatures) helps prevent harmful ultraviolet rays of the sun from reaching the earth s surface. Pollutants in the atmosphere may have a detrimental effect on this ozone layer. Ozone is toxic and exposure should not exceed 0.2 mg/m (8-hour time-weighted average - 40-hour work week). Undiluted ozone has a bluish color. Liquid ozone is bluish black and solid ozone is violet-black.  [c.21]

It is very poisonous, 50 mg constituting an approximate fatal dose. Exposure to white phosphorus should not exceed 0.1 mg/ms (8-hour time-weighted average - 40-hour work week). White phosphorus should be kept under water, as it is dangerously reactive in air, and it should be handled with forceps, as contact with the skin may cause severe burns.  [c.36]

Exposure to chlorine should not exceed 0.5 ppm (8-hour time-weighted average - 40 hour week.)  [c.42]

While silver itself is not considered to be toxic, most of its salts are poisonous. Exposure to silver (metal and soluble compounds, as Ag) in air should not exceed 0.01 mg/nu, (8-hour time-weighted average - 40 hour week). Silver compounds can be absorbed in the circulatory system and reduced silver deposited in the various tissues of the body. A condition, known as argyria, results with a grayish pigmentation of the skin and mucous membranes. Silver has germicidal effects and kills many lower organisms effectively without harm to higher animals.  [c.65]

Exposure to nickel metal and soluble compounds (as Ni) should not exceed 0.05 mg/cms (8-hour time-weighted average - 40-hour work week). Nickel sulfide fume and dust is recognized as being potentially carcinogenic.  [c.68]

Exposure to cobalt (metal fumes and dust) should be limited to 0.05 mg/ms (8-hour time-weighted average 40-hour week).  [c.84]

Exposure to rhodium (metal fume and dust, as Rh) should not exceed 1 mg/m 3 (8-hour time-weighted average, 40-hour week).  [c.111]

Care should be taken in handling and using iodine, as contact with the skin can cause lesions iodine vapor is intensely irritating to the eyes and mucus membranes. The maximum allowable concentration of iodine in air should not exceed 1 mg/nu (8-hour time-weighted average -40-hour).  [c.123]

Exposure to hafnium should not exceed 0.5 mg/hr. (8 hour time-weighted average - 40-hour week).  [c.131]

Concentrations in air as low as IO7 g/ms can cause lung congestion, skin damage, or eye damage. Exposure to osmium tetroxide should not exceed 0.0016 mg/ms (8-hour time weighted average - 40-hour work week).  [c.141]

The element and its compounds are toxic and should be handled carefully. Contact of the metal with skin is dangerous, and when melting the metal adequate ventilation should be provided. Exposure to thallium (soluble compounds) - skin, as Tl, should not exceed 0.1 mg/ms (8-hour time-weighted average - 40-hour work week). Thallium is suspected of carcinogenic potential for  [c.145]

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.  [c.1198]

Time-weighted average (TWA)  [c.993]

TWA. See Time-weighted average.  [c.1032]

Although acetonitrile has a low order of acute toxicity by ingestion, inhalation, and skin absorption, it can cause severe eye bums. In case of eye contact, eyes should be immediately flushed with water for at least 15 min and a physician should be consulted. In the event of a spiH or leak, the spiH should be contained, flooded with water, and disposed of according to local regulations. Acetonitrile is flammable (see Table 2) and must be kept away from excessive heat, sparks, and open flame. Associated fires can be extinguished using water spray, alcohol foam, CO2, or dry chemical extinguishers. OSHA requites that an employee s exposure to acetonitrile in any 8-h shift does not exceed a time-weighted average of 40 ppm (70 mg/m ) in air (30).  [c.219]

The U.S. Department of Labor (OSHA) has ruled that an employee s exposure to dimethyl acetamide in any 8-h work shift of a 40-h work week shall not exceed a time-weighted average of 10 ppm DMAC vapor in air by volume or 35 mg/m in air by weight (7). If there is significant potential for skin contact with DMAC, biological monitoring should be carried out to measure the level of DMAC metaboHtes in urine specimens collected at the end of the shift. One industrial limit is 40 ppm DMAC metaboHtes, expressed as AJ-methylacetamide [79-16-3] for individuals, and 20 ppm metaboHte average for workers on the job (8).  [c.85]

Acrylonitrile is categorized as a cancer hazard by OSHA. It has been determined to be carcinogenic to laboratory animals and mutagenic in both mammalian and nonmammalian tests. Genetic transformations and damage have been reported in tissue cultures exposed to acrylonitrile. Animal tests show that it is a reproductive toxicant only at maternally toxic doses. Permissible exposure limits for acrylonitrile in the United States are 2 ppm for an 8-h time-weighted average concentration and 10 ppm as the ceiling concentration for a 15-min period.  [c.185]

Styrene toxicity is regarded to be relatively low. It is an irritant to the eyes and respiratory tract, and while prolonged exposure to the skin may cause irritation, styrene is unlikely to be absorbed through the skin in harm fill amounts. The American Conference of Government Industrial Hygienists (ACGIH) threshold limit value (TLV) for styrene is 50 ppm time-weighted average (TWA) (155). More information on human exposure to styrene in the workplace is available (156,157) (see Styrene).  [c.197]

American Conference of Government Industrial Hygienists (ACGIH) threshold limit value = 5 ppm on an 8-h time-weighted average.  [c.472]

The American Conference of Governmental Industrial Hygienists (ACGIH) has estabUshed the 8-hour time-weighted average TLV as 1 ppm or 1.6 mg/m, and the short-term exposure limit TLV as 2 ppm or 3.1 mg/m. Fluorine has a sharp, penetrating odor detectable at levels well below the TLV. Manifestations of overexposure to fluorine include irritation or bums of the eyes, skin, and respiratory tract. The following emergency exposure limits (EEL) for humans have been suggested (107) 15.0 ppm for 10 min 10 ppm for 30 min and 7.5 ppm for 60 min.  [c.131]

The time-weighted average (TWA) concentrations for 8-h exposure to bromine ttifluoride, bromine pentafluoride, chlorine ttifluoride, chlorine pentafluoride, and iodine pentafluoride have been estabHshed by ACGIH on a fluoride basis to be 2.5 mg/m. NIOSH reports (121) the foUowing inhalation toxicity levels for chlorine ttifluoride LC q monkey, 230 ppm/h LC q mouse, 178 ppm/h for chlorine pentafluoride LC q monkey, 173 ppm /h mouse, 57 ppm/h.  [c.187]

Handling and Toxicity. Tungsten hexafluoride is irritating and corrosive to the upper and lower airways, eyes, and skin. It is extremely corrosive to the skin, producing bums typical of hydrofluoric acid. The OSHA permissible exposure limits is set as a time-weighted average of 2.5 mg/kg or 0.2 ppm (22).  [c.258]

OSHA has a standard time-weighted average (TWA) of 2.5 mg/m based on fluoride. NIOSH has issued a criteria document (24) on occupational exposure to inorganic fluorides.  [c.260]

The American Conference of Governmental Industrial Hygienists (ACGIH) has recommended that time weighted-average exposures for DMF not exceed 10 ppm or 30 mg/m (skin designation, 1989 standard) for an eight-hour work day. In the United States, OSHA has accepted the ACGIH limits ia setting regulations for worker exposures. As with other iadustrial chemicals, regulations and expert opinion evolve over time, and DMF exposure limits may be tightened ia the future. A Biological Exposure Index (BEI) of 40 mg DME metaboUtes /g of creatinine ia urine has also been adopted by ACGIH and apphes ia cases where there is significant potential for absorption of DME is Hquid or vapor through the skin.  [c.515]

The threshold limit value for the time-weighted average (8-h) exposure to pentanes is 600 ppm or 1800 mg/m (51 mg/SCF) the short-term exposure limit (15 min) is 750 ppm or 2250 mg/m (64 mg/SCF) (39). Pentanes are classified as simple asphyxiants and anesthetics (qv).  [c.404]

How Long to Sample. The period of the sample should be matched to the period of the exposure criteria. Most standards are referred to as eight hour time weighted averages (TWAs). These standards are for the average exposure over eight hours. Various combiaations of iadividual samples can be used to obtain the equivalent of what would have been measured by one sample of eight hours duration, as shown ia Figure 1. When the standard apphes to a shorter period, as for example a short-term exposure limit (STEL) which is a 15-min average, samples should be taken to measure over this shorter averaging time. Some limits are supposed to apply to instantaneous concentrations but because there are no truly instantaneous measurement methods (all have some response time) and because peak concentration is known to be a function of averaging time, these limits are somewhat undefined. The best solution when these limits are to be appHed is to make a very short (>1 min) period measurement.  [c.107]

Threshold limit value, time-weighted average.  [c.298]

Health and Safety Factors. MEK is slightly more toxic than acetone, but is not considered highly toxic, and nor does it exhibit cumulative toxicological properties. The OSHA time weighted average iu air is 200 ppm other measured toxicity values are shown iu Table 3. Methyl ethyl ketone is highly flammable.  [c.490]

Nickel Carbonyl. Nickel carbonyl is an extremely toxic gas. The permissible exposure limit (PEL) in the United States is 1 part per biUion (ppb) in air (127). The American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) for an 8-h, time-weighted average concentration is 50 ppb (128). Nickel carbonyl may form wherever carbon monoxide and finely divided nickel are brought together. Its occurrence has been suspected but never demonstrated in some industrial operations, eg, welding of nickel alloys.  [c.13]

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).  [c.103]

Health and Safety. Remover formulas that are nonflammable may be used in any area that provides adequate ventilation. Most manufacturers recommend a use environment of 50—100 parts per million (ppm) time weighted average (TWA). The environment can be monitored with passive detection badges or by active air sampling and charcoal absorption tube analysis. The vapor of methylene chloride produces hydrogen chloride and phosgene gas when burned. Methylene chloride-type removers should not be used in the presence of an open flame or other heat sources such as kerosene heaters (8).  [c.551]

The toxicity of sodium peroxoborate is similar to that of the hexahydrate. The LD q (cat, intravenous) is 600 mg/kg the LD q (rabbit, intravenous) is 78 mg/kg (28). Sodium peroxoborate is a severe eye irritant, but not a skin irritant. Absorption through large areas of abraded or damaged skin can give systemic boron poisoning (2). The maximum eight-hour time-weighted average exposure is 5 mg/m (2).  [c.93]

Phenol fumes are irritating to the eyes, nose, and skin. According to the National Institute for Occupational Safety and Health (NIOSH), exposure to phenol should be controUed so that no employees are exposed to phenol concentrations >20 mg/m, which is a time-weighted average concentration for up to a 10-h work day, 40-h work week. Phenol is very toxic to fish and has a nearly unique property of tainting the taste of fish if present in marine  [c.290]

Formaldehyde. The toxicology and possible carcinogenicity of formaldehyde have been a matter of intense research. Formaldehyde is classified as a probable human carcinogen by the International Agency for Research on Cancer (lARC) and as a suspected human carcinogen by the American Conference of Governmental and Industrial Hygienists (ACGIH) the latter has lowered its TLV to 0.3 ppm. The Occupational Safety and Health Administration (OSHA) has set its time-weighted average for eight hours at 1.0 ppm and its short-term exposure level at 2.0 ppm (67).  [c.302]

The odor threshold for phosgene is ca 0.5—1 ppm, but it varies with individuals and is higher after prolonged exposure (53). Phosgene may irritate eyes, nose, and throat. The permissible exposure TLV by volume in air is 0.1 ppm (54). The TLV refers to the average airborne concentration at which it is beheved nearly aU workers may be repeatedly exposed on a daily basis without adverse effect. It is a time-weighted average for an 8-h day or a 40-h week and should be used as a guide for control only. The guideline for excursion limits above the TLV is 0.2 ppm (55). Long-term exposure to phosgene has been reviewed, and potential hazards may exist at concentrations slightly higher than the TLV (56). Medical problems and adverse health effects associated with phosgene exposure have been reviewed (57—59), and therapy for phosgene poisoning has also been reviewed (60).  [c.314]

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.  [c.318]

Ceiling value concentration which should not be exceeded not appropriate to use a time-weighted average.  [c.95]

Hydrogen selenide in a concentration of 1.5 ppm is intolerable to man. Selenium occurs in some solid in amounts sufficient to produce serious effects on animals feeding on plants, such as locoweed, grown in such soils. Exposure to selenium compounds (as Se) in air should not exceed 0.2 mg/m3 (8-hour time-weighted average - 40-hour week).  [c.97]

Germanium compounds generally have a low order of toxicity (24). Only germane [7782-65-2] GeH, is considered toxic, having a maximum time-weighted average 8-h safe exposure limit of only 0.2 ppm (48). The lethal dose median for Ge02 is 750 mg/kg, and that of germanium is 586 mg/kg (49). The toxicity of specific germanium compounds usually must be considered more from the standpoint of the other part of the compound than from the Ge content. The biological activity of germanium has been reviewed (24).  [c.281]

Nitric acid and the oxides of nitrogen found in its fumes are highly toxic and capable of causing severe injury and death. It is corrosive and can destroy human tissue. Nitric acid is regulated by OSHA, which Hsts it as a Process Safety Hazardous Chemical and Air Contaminant. Under SARAH, the EPA Hsts it as an Extremely Hazardous Substance and Toxic Chemical. Per OSHA, the 1991 permissible exposure limits for nitric acid are 2 ppm (5 mg/m ) for an 8-h time-weighted average and 4 ppm (10 mg/m ) for a 15-min short-term exposure. Exposure limits may vary according to local and national regulations. Inhalation symptoms may take several hours to appear. They include irritation of the throat and nose, coughing, chest pain, difficulty in breathing, giddiness, nausea, ulceration of the nasal mucous membranes, pulmonary edema, and chemical pneumonia. The symptoms resulting from skin contact vary from moderate irritation to severe bum, depending on contact time and strength of the nitric acid. Signs of contact may include a yellow discoloration of the skin severe bums may penetrate deeply causing ulceration and the scarring of tissue.  [c.47]

Human Exposure to Ozone. The toxicity of ozone is largely related to its powerful oxidizing properties. The odor threshold of ozone varies among individuals but most people can detect 0.01 ppm in air, which is well below the limit for general comfort. OSHA has estabhshed a time-weighted average permissible exposure level for workers for an eight-hour day of 0.10 ppm v/v (0.2 mg/m ) and a short-term exposure limit of 0.30 ppm v/v (0.6 mg/m ) for an exposure less than 15 minutes (160). The latter is based on observations showing that significant declines in pulmonary function can result from repeated intermittent exposures or from a single short-term exposure to ozone. The toxicity of gaseous ozone varies with concentration and exposure time (161). The symptoms experienced on exposure to 0.1—1 ppm ozone ate headache, throat dryness, irritation of the respiratory passages, and burning of the eyes caused by the formation of aldehydes and petoxyacyl nitrates. Exposure to 1—100 ppm ozone can cause asthma-like symptoms such as tiredness and lack of appetite. Short-term exposure to higher concentrations can cause throat irritations, hemorrhaging, and pulmonary edema. Additional toxicity data is given in Reference 162.  [c.504]

Phosphine has an 8-h time-weighted average exposure limit of 0.3 ppm (13). Under alkaline conditions the rate of PH formation is high. At neutral or acidic pH, the PH generation is slow but stiU very ha2ardous if the PH is allowed to accumulate in a confined vapor space. The safest commercial handling conditions for molten phosphoms are generally considered to be from pH 6 to 8 at 45—65°C.  [c.352]

Phosphoms(V) sulfide is a mild skin irritant and may cause dermatitis in sensitive individuals. The primary health ha2ard results from the Hberation of hydrogen sulfide after contact with moisture. Contact with moisture also forms phosphoric acid. A secondary ha2ard is the formation of sulfur dioxide when phosphoms(V) sulfide bums. The oral LD q of in rats is 389 mg/kg the OSHA standard time-weighted average (TWA) is 1 mg /m (33).  [c.365]

Health and Safety Factors. Trimellitic anhydride may cause respiratory irritation and, in some cases, individuals exposed over long periods may become sensitized and experience mild to severe reactions upon subsequent exposure. It should be handled with caution and treated as a toxic agent in the workplace because exposure may result in irritation of the pulmonary tract, eyes, nose, and skin (117), immunological sensitization and, in rare cases, hemolytic anemia and noncardiac pulmonary edema. Allowable and recommended exposure limits have been estabUshed by the Occupational Safety and Health Administration for a permissible exposure limit (PEL), the American Conference of Governmental Industrial Hygienists for a threshold limit value (TLV), and Amoco for a ceiling limit are aU 0.4 mg/m. The PEL and TLV are an 8-h time-weighted average. The mean lethal acute oral dosage in rats is 5.6 g/kg. Handling precautions include effective ventilation and use of respirators, protective clothing, and goggles when exposure to dust is expected.  [c.497]


See pages that mention the term Time-weighted average : [c.397]    [c.114]    [c.224]    [c.568]    [c.488]    [c.239]   
Industrial ventilation design guidebook (2001) -- [ c.0 ]