Explore chapters and articles related to this topic
Building-Associated Illnesses
Published in David L. Hansen, Indoor Air Quality Issues, 2018
Acting under the authority of the Occupational Safety and Health Act of 1970, the National Institute of Occupational Safety and Health (NIOSH), which is the technical arm of OSHA, develops and periodically revises recommended exposure limits for hazardous substances or conditions in the industrial workplace. These recommended exposure limits (RELs) are then published in the Federal Register and used in promulgating legal standards. Once the RELs become a legal standard, they are called permissible exposure levels (PELs) and are enforceable under law. These standards must be conformed to by industry and are the benchmark for deciding if an industrial workplace is “safe and healthy.”
Toxic and Asphyxiating Hazards in Confined Spaces
Published in Neil McManus, Safety and Health in Confined Spaces, 2018
Recommended Exposure Levels (RELs) and Immediately Dangerous to Life or Health limits (IDLHs) were prepared by the National Institute for Occupational Safety and Health as part of the Standards Completion Project (NIOSH 1990). REL-TWA is the time-weighted average concentration for up to a 10-h workday during a 40-h workweek. A short-term exposure limit (REL-STEL) is a 15-min time-weighted average that should not be exceeded at any time during a workday. A ceiling level (REL-Ceiling) should not be exceeded at any time. IDLH was defined for the purpose of selecting respiratory protection. IDLH represents the presumed maximum concentration from which a person could escape in 30 min in the event of respirator failure without experiencing any escape-impairing or irreversible health effects.
A comparison of hourly with annual air pollutant emissions: Implications for estimating acute exposure and public health risk
Published in Journal of the Air & Waste Management Association, 2019
Michael J. Stewart, James Hirtz, George M. Woodall, Chelsea A. Weitekamp, Kelley Spence
California reference exposure level (REL) values meet RTR program criteria. REL values represent 1-hr exposure concentrations below which no adverse health effect is expected, including in sensitive groups (California Environmental Protection Agency Office of Environmental Health Hazard Assessment [OEHHA] 2008, 2014) (Table S1). However, of the 303 HAP chemical and HAP-related compounds listed on the EPA Office of Air Quality Planning and Standard’s (OAQPS) air toxics dose-response value list (OAQPS 2017), only 42 (14%) of these chemicals/compounds have an REL value (Table 4). In the absence of an REL value, the RTR program may use a severity level 1 (mild, reversible effects) Acute Exposure Guideline Level (AEGL-1) (Department of Energy [DOE] 2016; NRC 2001) or Emergency Response Planning Guideline Level (ERPG-1) (American Industrial Hygiene Association [AIHA] 2002; DOE 2016) to estimate acute risk (Table S1). These other values are used even though they are meant to be used in emergency response situations, are derived for a once in lifetime exposure, and represent concentrations at which health effects are likely to occur. Moreover, it is important to note that exposure concentrations below the AEGL-1 can still result in mild adverse effects (EPA 2018) and that the elderly, sick, and very young are not covered by ERPG values (National Oceanic and Atmospheric Administration [NOAA] 2018). If these values are included, approximately 25% of HAP chemicals/compounds have either an REL, AEGL-1, or ERPG-1 (Figure 3a). If HHRVs representing severity level 2 effects (irreversible effects or impairment of the ability to escape exposure) are also included, then about 33% of these chemicals/compounds have an hourly reference value (Figure 3a).
Occupational health risk assessment of volatile organic compounds emitted from the coke production unit of a steel plant
Published in International Journal of Occupational Safety and Ergonomics, 2020
Fateme Dehghani, Fariborz Omidi, Omidreza Heravizadeh, Saied Barati Chamgordani, Vahid Gharibi, Akbar Sotoudeh Manesh
BTEX compounds are known as carcinogens or non-carcinogens with respect to their toxicity. Benzene (class A) and ethylbenzene (class 2B) have been considered as carcinogens while toluene and xylene have been regarded as non-carcinogens. Cancer health risk assessments were conducted for benzene and ethylbenzene; non-cancer health assessments were done for both carcinogen and non-carcinogen compounds based on chronic exposure data. To conduct health risk assessment, the inhalation route was considered the main path of exposure. The carcinogenic and non-carcinogenic inhalation intakes of the chemicals were calculated as follows [16]: where I = average daily inhalation intake (μg/m3); C = concentration of the related compound in the personal air monitoring sample (μg/m3); ET = exposure time (hours/day); EF = exposure frequency (days/year); ED = exposure duration (years); AT = average lifetime (hours). Parameter values for the exposure assessment are presented in Table 2. In the risk characterization step, the information from exposure assessment and toxicity data steps is incorporated to develop risk estimates. In this study, the cancer risk for the chemicals with a cancer endpoint was estimated, using the following equation [9]: where I = inhalation intake (μg/m3). The non-carcinogenic risks associated with exposure to chemicals were assessed using the hazard quotient (HQ) method [22], which is calculated by dividing the inhalation intake (I) by the reference exposure level (REL): where REL = concentration at or below which no adverse health effects are anticipated for a specified exposure period. Table 3 presents the REL and cancer unit risk for the chemicals of interest [23]. HQ values greater than unity indicate that the intake concentration is higher than the reference exposure level and adverse health effects are likely to occur.