5 Control at the Source Chemical substitution Redesign the process Isolate the processEnclose the processMechanize
6 Control of the Path Local exhaust ventilation General ventilation HousekeepingWork methods (wetting down, etc.)
7 Control at the Worker Respirators and other PPE Administrative controlsEnclose the workerHygiene facilities and practices
8 Hierarchy of Control Control the source Control the path Control the exposure at the worker
9 Hierarchy of Control Engineering Administration Personal protective equipment (PPE)
10 Types of Illnesses - Time Acute - a disease that develops quickly after exposureChronic - a disease that develops long after exposureLatency Period - the time between the first exposure and the development of disease
11 Routes of Exposure Breathe the chemical – inhalation Swallow the chemical – ingestionAbsorb through skin - skin absorptionIn all cases, chemicals can travelthrough the body.
12 Important Body Organs Lungs Kidney Blood Forming Reproductive Nervous System Liverbrainnerves
13 Forms of Chemicals Particles Dust - formed by Grinding /breaking - large particlesSmoke - formed by burning - large particlesFume - formed by heating - small particles
14 Forms of Chemicals Gasses Gas - at room temperature Vapor - heat to turn to gas ---Droplets - agitating a liquid
17 Signs of Exposure Dust, Mist, Smoke in the air Accumulation of dust or oilsUnusual SmellsUnusual TastesBurning in the eyesNose throat irritationFeel better during vacation
18 Contributory Factors to Toxicity DoseAbsorptionRate of TransformationExcretion RateHuman FactorsRoute of Entry
19 Measuring Particles Concentration Weight of substance in volume of air Weight in milligrams - mgVolume in cubic meters m3mg/m3 = milligrams per cubic meter
20 Measuring Gasses or Vapors Volume concentration of gas in airParts per millionParts of gas in million parts of airCups in a million cupsQuarts in a million quartsSimilar to per cent, which is actually parts per hundred
21 OSHA PEL’s PEL = Permissible Exposure Limit The concentration of a chemical a worker can be exposed to . . .8 hours per dayworking lifetimewithout experiencing health problems
22 Kinds of PEL’s TWA = Time Weighted Average Levels vary over a day OK for chemicals causing chronic disease
28 STEL STEL = Short term exposure limit Period of time shown in standard where PEL can be exceededStill an absolute maximum that can not be exceeded (a ceiling)Must still meet the TWA
29 Skin Notation If OSHA says “skin,” then can’t have any skin contact Appropriate where there is [a possibility of] skin absorption
30 How Do We Get These PEL’s? Concensus standards ACGIH, 1968ANSINew standards attempted to upgrade not successful
31 Other Sources of Standards ACGIH - TLV’sNIOSH - REL’sCompany standards
32 Table Z-1 Based on 1968 ACGIH Lists chemical name CAS (identifying) numberPEL (Time Weighted Average)Skin (if applies)Ceiling (if applies)
33 11/10/1999 - OSHA policy regarding PEL adjustments for extend work shifts As stated in a previous memorandum dated November 8, 1996:Compliance officers can choose one of two approaches for employees who work extended work shifts beyond 8-hours. The choice taken will depend on the nature of the hazardous chemical.
34 PEL AdjustmentsThe first approach is to sample what the compliance officer believes to be the worst continuous 8-hour work period of the entire extended work shift.
35 PEL AdjustmentsThe second approach is to collect multiple samples over the entire work shift. Sampling is done such that multiple personal samples are collected during the first 8-hour work period and additional samples are collected for the extended work shift. Unless a compliance officer is dealing with lead, the PEL in this approach is calculated based upon the worst 8-hours of exposure during the entire work shift.
36 Table Z-2 Based on ANSI standards Lists chemical name CAS number TWA Acceptable ceilingPeakDuration
37 (b) - Table Z-2"Acceptable ceiling concentrations." An employee's exposure to a substance listed in Table Z-2 shall not exceed at any time during an 8-hour shift the ceiling concentration limit given for the substance except for:A time period, and up to a concentration not exceeding the maximum duration and concentration allowed in the column under "acceptable maximum peak above the acceptable ceiling concentration for an 8-hour shift"
38 (b) - Table Z-2PeakThe substances listed can have limits expressed as:8-hour TWAsCeilingsPeaksIf a substance has both ceiling and peak limits, the peak is the level never to be exceededEmployee exposure level exceeding the ceiling but under the peak are required to comply with the margin notes provided in the table
39 (b) - Table Z-2Example:During 8-hour work shift, an employee may be exposed to Substance A (with a 10 ppm TWA, 25 ppm ceiling, and 50 ppm peak) above 25 ppm (but never above 50 ppm) only for a maximum period of 10 minutes.Such exposure must be compensated by exposures to concentrations less than 10 ppm so that the cumulative exposure for the entire 8-hour work shift does not exceed a weighted average of 10 ppm.
40 Table Z-3 Mineral Dusts silica and silicates graphite coal dust Inert or nuisance dusts(particulates not otherwise classified)Respirable: < 10 micronsseparated with cyclone
41 Substance Specific Standards 31 specific chemicalsasbestosbenzenecoal tar pitch volatilesleadformaldehydearsenic
42 Substance Specific Requirements Air monitoringControl of exposureWork practicesRespiratory protectionMedical surveillancemedical removal (lead)Record keepingWorker training
43 Air Monitoring: Who, What, Where? Worst case samplingRepresentative samplingPersonal vs. area samplingWhat conditions can affect sampling results?
44 Chemical Properties Flashpoint Vapor Density Vapor Pressure Specific GravityEvaporation Rate
45 Air MonitoringPumpTubeCollection deviceDirect reading
46 Air MonitoringCalibrate pump with collection device before and after each sampleSample minimum of one hour less than full shift (for OSHA compliance)
47 Napthalene Exposures15 ppm for 6 hours5 ppm for 2 hours
48 Compute TWA 15 ppm x 6 hours = 90 ppm hrs 5 ppm x 2 hour = 10 ppm hrs ____________________________100 ppm hrs ÷ 8 hours = 13.8 ppm
49 Less Than Full Shift Sample? 15 ppm x 7 hours = 105 ppm hrs? ppm x 1 hour = ??? ppm
50 Confidence LimitsC / PEL = YLCL = y - SAEUCL = y + SAE