{"id":4521,"date":"2017-09-07T09:33:45","date_gmt":"2017-09-07T14:33:45","guid":{"rendered":"https:\/\/wp.stolaf.edu\/chemical-hygiene\/?page_id=4521"},"modified":"2023-06-07T08:12:19","modified_gmt":"2023-06-07T13:12:19","slug":"exposure-limits-you-must-follow-these","status":"publish","type":"page","link":"https:\/\/wp.stolaf.edu\/chemical-hygiene\/exposure-limits-you-must-follow-these\/","title":{"rendered":"Exposure Limits: You Must Follow These"},"content":{"rendered":"<div data-modular-content-collection><p><img loading=\"lazy\" decoding=\"async\" data-attachment-id=\"4853\" data-permalink=\"https:\/\/wp.stolaf.edu\/chemical-hygiene\/exposure-limits-you-must-follow-these\/hood-use-twa-50\/\" data-orig-file=\"https:\/\/wp.stolaf.edu\/chemical-hygiene\/files\/2017\/09\/Hood-Use-TWA-50.jpg\" data-orig-size=\"624,323\" data-comments-opened=\"0\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;1&quot;}\" data-image-title=\"Hood Use TWA 50\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/wp.stolaf.edu\/chemical-hygiene\/files\/2017\/09\/Hood-Use-TWA-50.jpg\" class=\"size-medium wp-image-4853 alignright\" src=\"https:\/\/wp.stolaf.edu\/chemical-hygiene\/files\/2017\/09\/Hood-Use-TWA-50-300x155.jpg\" alt=\"\" width=\"300\" height=\"155\" \/>In addition to skin contact, substances can be hazardous simply by being exposed to the atmosphere because the harmful vapors can then come in contact with or be absorbed into a person\u2019s body. \u00a0Therefore, most substances have some guidelines for exposure, such as OSHA\u2019s Permissible Exposure Limits (PEL) or ACGIH\u2019s Threshold Limit Values (TLV).<\/p>\n<p>&nbsp;<\/p>\n\n\n<!-- begin-migrated-from-panel-builder -->\t\t\t<div\n\t\t\tclass=\"site-section site-panel__tabs panel panel-tabs site-section__bg--default\"\n\t\t\tdata-depth=\"\"\n\t\t\tdata-js-panel=\"tabs\"\n\t\t>\n\t\n\t\t<div class=\"site-section__inner\" data-js=\"tabs\">\n\n\t\n\t\n\n\t\t\t\t<ul class=\"site-panel__tablist\" data-js=\"tab-list\" role=\"tablist\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<li class=\"site-panel__tab-item\" role=\"presentation\" data-js=\"tab-item\">\n\t\t\t\t\t<button\n\t\t\t\t\t\tclass=\"site-panel__tab-btn site-panel__tab-btn--active\"\n\t\t\t\t\t\tdata-js=\"site-panel__tab\"\n\t\t\t\t\t\tdata-target=\"site-panel__tab-content-1\"\n\t\t\t\t\t\trole=\"tab\"\n\t\t\t\t\t\taria-controls=\"site-panel__tab-content-1\"\n\t\t\t\t\t\taria-selected=\"false\"\n\t\t\t\t\t>\n\t\t\t\t\t\t<span class=\"u-visual-hide\">Show<\/span>\n\t\t\t\t\t\t\tOSHA Permissible Exposure Limits (PEL)\n\t\t\t\t\t\t<span class=\"u-visual-hide\">Content<\/span>\n\t\t\t\t\t<\/button>\n\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<li class=\"site-panel__tab-item\" role=\"presentation\" data-js=\"tab-item\">\n\t\t\t\t\t<button\n\t\t\t\t\t\tclass=\"site-panel__tab-btn  \"\n\t\t\t\t\t\tdata-js=\"site-panel__tab\"\n\t\t\t\t\t\tdata-target=\"site-panel__tab-content-2\"\n\t\t\t\t\t\trole=\"tab\"\n\t\t\t\t\t\taria-controls=\"site-panel__tab-content-2\"\n\t\t\t\t\t\taria-selected=\"false\"\n\t\t\t\t\t>\n\t\t\t\t\t\t<span class=\"u-visual-hide\">Show<\/span>\n\t\t\t\t\t\t\tOSHA Action Levels\n\t\t\t\t\t\t<span class=\"u-visual-hide\">Content<\/span>\n\t\t\t\t\t<\/button>\n\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<li class=\"site-panel__tab-item\" role=\"presentation\" data-js=\"tab-item\">\n\t\t\t\t\t<button\n\t\t\t\t\t\tclass=\"site-panel__tab-btn  \"\n\t\t\t\t\t\tdata-js=\"site-panel__tab\"\n\t\t\t\t\t\tdata-target=\"site-panel__tab-content-3\"\n\t\t\t\t\t\trole=\"tab\"\n\t\t\t\t\t\taria-controls=\"site-panel__tab-content-3\"\n\t\t\t\t\t\taria-selected=\"false\"\n\t\t\t\t\t>\n\t\t\t\t\t\t<span class=\"u-visual-hide\">Show<\/span>\n\t\t\t\t\t\t\tACGIH Threshold Limit Values (TLV\u00ae) and Biological Exposure Indices (BEI\u00ae)\n\t\t\t\t\t\t<span class=\"u-visual-hide\">Content<\/span>\n\t\t\t\t\t<\/button>\n\t\t\t\t<\/li>\n\t\t\t\t\t<\/ul>\n\t\n\t\t\t\t<div class=\"site-panel__tab-content-container\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div id=\"site-panel__tab-content-1\" class=\"site-panel__tab-content site-panel__tab-content--active\" role=\"tabpanel\" aria-hidden=\"true\">\n\t\t\t\t\t<article class=\"panel panel-child panel--type-wysiwyg\">\n\t\t\t\t\t\t<div class=\"site-section site-panel__wysiwyg panel panel-wysiwyg site-section__bg--default\" data-depth=\"1\" data-js-panel=\"wysiwyg\">\n\t\t\t\t\t\t\t<div class=\"site-section__inner l-wrapper\">\n\t\t\t\t\t\t\t\t<div class=\"site-section__content \">\n\t\t\t\t\t\t\t\t\t<div class=\"site-grid site-grid__wrapper site-grid__wrapper-stagger\" data-depth=\"0\" data-name=\"columns\" data-livetext>\n\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"site-grid__col\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"site-panel__wysiwyg-content\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"t-content  site-section \" data-depth=\"0\" data-index=\"0\" data-autop=\"true\" data-name=\"column_content\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<p>OSHA set PELs to protect workers against the health effects of exposure to hazardous substances. \u00a0The PELs are limits on the concentration of a substance in the air, and they may also contain a skin designation. The numbers are usually expressed in parts per million (ppm) or mg\/m<sup>3<\/sup>.<br \/>\nIn 1989, federal OSHA revised its PELs under 29 CFR 1910.1000, which Minnesota OSHA adopted. \u00a0Although federal OSHA has since reverted to the pre-1989 PELs, Minnesota OSHA still enforces the\u00a0<a href=\"https:\/\/www.dli.mn.gov\/OSHA\/PDF\/pels.pdf\" target=\"_blank\" rel=\"noopener\"><strong>1989 PELs<\/strong><\/a>\u00a0for substances that are not covered by separate standards.<\/p>\n<ul>\n<li>The PELs (found in <a href=\"https:\/\/www.dli.mn.gov\/OSHA\/PDF\/pels.pdf\" target=\"_blank\" rel=\"noopener\">Table Z-1-A<\/a>) are measured in one of three ways:\n<ul>\n<li><strong>Ceiling<\/strong> is the employee\u2019s exposure that shall not be exceeded during any part of the work day. \u00a0If instantaneous monitoring is not feasible, then the ceiling shall be assessed as a 15-minute time weighted average exposure which shall not be exceeded at any time over a working day.<\/li>\n<li><strong>Time Weighted Average<\/strong> (TWA) is the employee\u2019s average airborne exposure in any 8-hour work shift of a 40-hour work week which shall not be exceeded.<\/li>\n<li><strong>Short Term Exposure Limit<\/strong> (STEL) is the employee\u2019s 15-minute time weighted average exposure that shall not be exceeded at any time during a work day unless another time limit is specified in a parenthetical notation below the limit. \u00a0If another time period is specified, the time weighted average exposure over that time period shall not be exceeded at any time during the working day.<\/li>\n<\/ul>\n<\/li>\n<li><strong>An employee\u2019s exposure<\/strong> to any substance listed in <a href=\"https:\/\/www.dli.mn.gov\/OSHA\/PDF\/pels.pdf\" target=\"_blank\" rel=\"noopener\">Table Z-1-A <\/a><strong>shall not exceed<\/strong> the Time Weighted Average (TWA), Short Term Exposure Limit (STEL) and Ceiling Limit specified for that substance in Table Z-1-A.<\/li>\n<\/ul>\n\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t<\/div><!-- .site-grid__col -->\n\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div><!-- .site-grid, .site-grid__wrapper -->\n\t\t\t\t\t\t\t\t<\/div><!-- .site-section__content -->\n\t\t\t\t\t\t\t<\/div><!--.site-section__inner -->\n\t\t\t\t\t\t<\/div><!-- .site-section -->\n\t\t\t\t\t<\/article>\n\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div id=\"site-panel__tab-content-2\" class=\"site-panel__tab-content  \" role=\"tabpanel\" aria-hidden=\"true\">\n\t\t\t\t\t<article class=\"panel panel-child panel--type-wysiwyg\">\n\t\t\t\t\t\t<div class=\"site-section site-panel__wysiwyg panel panel-wysiwyg site-section__bg--default\" data-depth=\"1\" data-js-panel=\"wysiwyg\">\n\t\t\t\t\t\t\t<div class=\"site-section__inner l-wrapper\">\n\t\t\t\t\t\t\t\t<div class=\"site-section__content \">\n\t\t\t\t\t\t\t\t\t<div class=\"site-grid site-grid__wrapper site-grid__wrapper-stagger\" data-depth=\"0\" data-name=\"columns\" data-livetext>\n\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"site-grid__col\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"site-panel__wysiwyg-content\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"t-content  site-section \" data-depth=\"0\" data-index=\"0\" data-autop=\"true\" data-name=\"column_content\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<ul>\n<li>An Action Level, calculated as an eight (8)-hour time-weighted average (and generally lower than the PEL), is a concentration designated for specific substances listed in 29 CFR part 1910 that initiates certain required activities such as exposure monitoring and medical surveillance.<\/li>\n<li>For example, the PEL for lead is 50ug\/m<sup>3<\/sup> while the Action Level is 30ug\/m<sup>3<\/sup>.<\/li>\n<li><strong>Actions Levels must be followed<\/strong>.<\/li>\n<\/ul>\n\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t<\/div><!-- .site-grid__col -->\n\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div><!-- .site-grid, .site-grid__wrapper -->\n\t\t\t\t\t\t\t\t<\/div><!-- .site-section__content -->\n\t\t\t\t\t\t\t<\/div><!--.site-section__inner -->\n\t\t\t\t\t\t<\/div><!-- .site-section -->\n\t\t\t\t\t<\/article>\n\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div id=\"site-panel__tab-content-3\" class=\"site-panel__tab-content  \" role=\"tabpanel\" aria-hidden=\"true\">\n\t\t\t\t\t<article class=\"panel panel-child panel--type-wysiwyg\">\n\t\t\t\t\t\t<div class=\"site-section site-panel__wysiwyg panel panel-wysiwyg site-section__bg--default\" data-depth=\"1\" data-js-panel=\"wysiwyg\">\n\t\t\t\t\t\t\t<div class=\"site-section__inner l-wrapper\">\n\t\t\t\t\t\t\t\t<div class=\"site-section__content \">\n\t\t\t\t\t\t\t\t\t<div class=\"site-grid site-grid__wrapper site-grid__wrapper-stagger\" data-depth=\"0\" data-name=\"columns\" data-livetext>\n\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"site-grid__col\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"site-panel__wysiwyg-content\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"t-content  site-section \" data-depth=\"0\" data-index=\"0\" data-autop=\"true\" data-name=\"column_content\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<p>The American Conference of Governmental Industrial Hygienists (ACGIH; <a href=\"http:\/\/www.acgih.org\" target=\"_blank\" rel=\"noopener\">http:\/\/www.acgih.org<\/a>) is \u201can organization devoted to the administrative and technical aspects of occupational and environmental health.\u201d \u00a0The TLVs<sup>\u00ae<\/sup> and BEIs<sup>\u00ae<\/sup> were developed by the ACGIH to \u201crecommend airborne concentrations of agents and exposure conditions for use in the practice of industrial hygiene and by other qualified professionals to protect worker health.\u201d<\/p>\n<ul>\n<li>TLVs<sup>\u00ae<\/sup> andBEIs<sup>\u00ae<\/sup>\u00a0are not regulatory standards, but they do represent a scientific opinion based on a review of existing peer-reviewed scientific literature by committees of experts in public health and related sciences.<\/li>\n<li>TLVs<sup>\u00ae<\/sup> andBEIs<sup>\u00ae<\/sup>\u00a0(when known) can be found on <a href=\"https:\/\/wp.stolaf.edu\/chemical-hygiene\/safety-data-sheets\/\" target=\"_blank\" rel=\"noopener\">Safety Data Sheets<\/a> and in <a href=\"https:\/\/wp.stolaf.edu\/chemical-hygiene\/hazard-id-additional-resources\/\" target=\"_blank\" rel=\"noopener\">PubChem<\/a>.<\/li>\n<\/ul>\n\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t<\/div><!-- .site-grid__col -->\n\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div><!-- .site-grid, .site-grid__wrapper -->\n\t\t\t\t\t\t\t\t<\/div><!-- .site-section__content -->\n\t\t\t\t\t\t\t<\/div><!--.site-section__inner -->\n\t\t\t\t\t\t<\/div><!-- .site-section -->\n\t\t\t\t\t<\/article>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\n\t\t<\/div>\n\n\t\t\t<\/div>\n\t\n<!-- end-migrated-from-panel-builder --><\/div>","protected":false},"excerpt":{"rendered":"<p>In addition to skin contact, substances can be hazardous simply by being exposed to the atmosphere because the harmful vapors can then come in contact with or be absorbed into 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