For NIOSH RELs, “ TWA ” indicates a time-weighted average concentration for up to a 10-hour workday during a 40-hour workweek. A short-term exposure limit (STEL) is designated by “ ST ” preceding the value; unless noted otherwise, the STEL is a 15-minute TWA exposure that should not be exceeded at any time during a workday.

1995年10月6日 · "TWA is the employee's average airborne exposure in any 8-hour work shift of a 40-hour work week which shall not be exceeded." The 8-hour TWA PEL is the level of exposure established as the highest level of exposure an employee may be exposed to without incurring the risk of adverse health effects.

2024年2月16日 · Time Weighted Average (TWA) is the average noise level during a shift (usually 8 hours). It considers both noise levels and how long the employee is exposed at each noise level. Measure workplace areas with a sound level meter (SLM) and create a …

RELs are for up to 10-hour time weighted averages (TWAs) during a 40-hour work week unless otherwise indicated. NIOSH has established occupational exposure limits for compounds not included in the OSHA Z Tables. Please see the NIOSH Pocket Guide for additional limits, skin absorption and other designations, and explanations.

我国在GBZ 2.1的制定过程中系统参阅了美国政府工业卫生师协会(American Conference of Government Industrial Hygienists,ACGIH)、美国国立职业安全卫生研究所(National Institute for Occupational Safety and Health, NIOSH)及美 国职业安全与健康管理局(Occupational Safety and Health Administration,OSHA)等国家和组织的有关标准和文件,但与美国职业接触限值的不同类型OELs 的数量与具体差异。

2021年1月5日 · NIOSH: Occupational Health Guideline for Nitrogen Dioxide. 1978. Pathmanathan, S., Krishna, M.T., Blomberg, A., Helleday, R., Kelly, F.J., Sandstrom, T., Holgate, S.T., Wilson, S.J., Frew, A.J.: Repeated daily exposure to 2 ppm nitrogen dioxide upregulates the expression of IL-5, IL-10, IL-13, and ICAM-1 in the bronchial epithelium of healthy ...

2024年11月26日 · NIOSH STEL: NIOSH's recommended short-term exposure limit; a 15-minute TWA exposure which should not be exceeded at any time during a workday. See NIOSH Pocket Guide to Chemical Hazards .

2020年2月5日 · A Recommended Exposure Limit, or REL, is based on research done at NIOSH. A REL is most commonly a 10-hour TWA (although some do exist as 8-hour limits). NIOSH is the CDC funded research complement to OSHA, however the REL is also not directly enforceable and is considered a consensus standard as well.

NIOSH. At concentrations above the NIOSH REL, or where there is no REL, at any detectable concentration: (APF = 10,000) Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode

Methods: Daily 8-hour time-weighted average (TWA) personal noise exposures were obtained for 61 workers using dosimeters set simultaneously to the NIOSH and OSHA Hearing Conservation Amendment (OSHA-HCA) criteria. A variety of work groups with the potential for noise exposure were evaluated as a part of this investigation.