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OSH 367 Human Factors Environmental Factors A summary of physical and chemical demands on workers Chapter 4: Environmental Factors Learning Objectives • By the end of this section participants will be able to: – Anticipate common environmental factors – Evaluate common environmental factors – Recommend controls for workers exposed to common environmental factors OSH 367 W6 PPT1 Environmental Factors 2 Environmental Factors • What are some of the environmental factors that my impact workers in your company? OSH 367 W6 PPT1 Environmental Factors 3 Environmental Factors • Physical and chemical hazards environmental factors such as: – – – – – Noise, Vibrations, Lighting, Climate, and Chemical substances can affect worker performance. OSH 367 W6 PPT1 Environmental Factors 4 Environmental Factors • In general, three types of measures (controls) can be applied to reduce or eliminate the adverse effects of environmental factors: – Source reduction or elimination – Transmission between the source and man (isolate the source and/or man) – At the individual level (reduction of exposure duration, PPE) OSH 367 W6 PPT1 Environmental Factors 5 Noise Overview • https://www.youtube.com/watch?v=Xz67mHD3TyY OSH 367 W6 PPT1 Environmental Factors 6 Noise? What is it exactly...??!! • Noise is defined as any sound that is undesired or interferes with one’s hearing of something. https://www.youtube.com/watch?v=hvQ5hZadFok OSH 367 W6 PPT1 Environmental Factors 7 Frequency and the Human Ear • Human speech:1000 – 4000 Hz • Humans lose sensitivity at: >1000Hz, and <4000Hz OSH 367 W6 PPT1 Environmental Factors 8 EAR Sections • Outer ear • Middle ear • Inner ear OSH 367 W6 PPT1 Environmental Factors 9 OUTER • Function is toEAR direct sound waves into the ear canal which leads to the eardrum • Eardrum passes this vibration on to the middle ear Pinna Ear Drum (Tympanic Membrane) Auditory Canal (Ear Canal) OSH 367 W6 PPT1 Environmental Factors 10 MIDDLE EAR Contains the three smallest bones in the body, the: • Hammer • Anvil • Stirrup The vibration moves the bones and passes sound waves to the inner ear Hammer Anvil Stirrup OSH 367 W6 PPT1 Environmental Factors Auditory Canal 11 INNER EAR Contains a fluid filled mechanism called the cochlea • Inside the cochlea are thousands of tiny hair cells which respond to the vibrations sound waves produce in the fluid • These hair cells pass the vibrations on to nerve fibers in the auditory nerve OSH 367 W6 PPT1 Environmental Factors 12 Exposure to Noise NIOSH estimates that > 4 million production workers are exposed to hazardous noise This represents approximately 17% of all production workers OSH 367 W6 PPT1 Environmental Factors 13 Performance Effects of Noise on Humans Communication Annoyance Job interference OSH 367 W6 PPT1 Environmental Factors 14 Audiometric Testing Assess your hearing ability Avoid high levels of noise during the 14 hours before your audiogram OSH 367 W6 PPT1 Environmental Factors 15 Auditory Effects of Noise Exposure What Exposure to Loud Noise Will Do • Exposure to loud noise will inevitably cause hearing loss over time. • Loud noise damages or destroys the nerves in the inner ear. • Another effect can be “tinnitus” or permanent ringing in the ear. OSH 367 W6 PPT1 Environmental Factors 16 Auditory Effects of Noise Exposure When is Noise Too Loud? • Noise is measured in units called “decibels” or “dB” • If two people 3 feet apart must shout to be heard, the background noise is too loud (above 85 decibels). • Noise above 140 decibels causes pain and immediate hearing loss. OSH 367 W6 PPT1 Environmental Factors 17 Other Effects of Noise on the Body • Vaso Constriction of Peripheral Blood Vessels • Decrease in Systolic/increase in Diastolic Blood Pressure • Fatigue • Vertigo • Tightening of body muscles • Salivatory and Gastric secretions • Decreased Respiration OSH 367 W6 PPT1 Environmental Factors 18 Characteristics of Noise-Induced Hearing Loss Main characteristics are Some individuals are more susceptible to noiseinduced hearing loss than others In the initial stages, noise-induced hearing loss is most pronounced at 4000 Hz but it spreads over other frequencies as noise level and/or exposure time increases 1000 Hertz 2000 Hertz 3000 Hertz 4000 Hertz 5000 6000 7000 8000 Hertz Hertz Hertz Environmental Hertz OSH 367 W6 PPT1 Factors 19 HEARING LOSS Sensori-Neural • Noise induced hearing loss • Results from the damage to the hair cells or auditory nerves Normal Cochlea Cochlea Severely Damaged By Noise Over Exposure OSH 367 W6 PPT1 Environmental Factors 20 Presbycusis Hearing sensitivity declines as people become older Like noise-induced hearing loss everyone is not affected equally Age-related hearing loss adds to noise-induced hearing loss Hearing ability may continue to worsen even after a person stops work in a noisy environment OSH 367 W6 PPT1 Environmental Factors 21 Noise Definitions • Sound Waves: • A form of general class of waves known as elastic waves. Can only occur in media which have properties of mass and elasticity. – Air – Water OSH 367 W6 PPT1 Environmental Factors 22 Noise Definitions • Frequency: – The number of times per second a vibrating body traces one complete cycle of motion. – Determines the nature of sound – Humans hear frequency as pitch – Low pitched sounds are low frequency sounds – High pitched are high frequency sounds OSH 367 W6 PPT1 Environmental Factors 23 Noise Definitions • Frequency: – – – – Measured in Cycles/Second= Hertz (Hz)=f One hertz in one cycle per second Kilohertz (kHz) 1 kHz = 1000 Hz Megahertz (MHz) 1 MHz = 1000 kHz A healthy young person can hear sounds in the frequency range of 20 – 20,000 Hz Human speech is mainly in the frequency range of 500 – 5,000 Hz OSH 367 W6 PPT1 Environmental Factors 24 Noise Definitions • Ultrasound: – Sounds above 16 kHz: – Not audible to people • Infrasounds – Sounds below 20 Hz – Not audible to people OSH 367 W6 PPT1 Environmental Factors 25 Noise Definitions • Wavelength: – Distance between two analogous points on two successive parts of the wave – Distance a sound wave travels in one cycle – Greek symbol lambda is used to express wavelength – Measured in feet or meters OSH 367 W6 PPT1 Environmental Factors 26 Noise Exposure Factors • • • • Intensity or Loudness Frequency Duration—Length of exposure Distance from the source OSH 367 W6 PPT1 Environmental Factors 27 Decibel The bel is a unit of measure in electrical communications engineering and the decibel is one-tenth of a bel This is the preferred unit of measure for sound and is the minimum difference in loudness that is usually perceptible By definition, the decibel is a dimensionless unit used to express the logarithm of the ratio of a measured quantity to a reference quantity Used to describe the level of quantities that are proportional to sound power OSH 367 W6 PPT1 Environmental Factors 28 Decibel Decibel scale is a very large scale that allows us to measure very large ranges of noise Very convenient to use It compresses the sound pressure range of 0.0002 Pa – 200 Pa into a manageable range of decibels from 0 – 140 dB OSH 367 W6 PPT1 Environmental Factors 29 Why Measure Noise Levels • Noise exposure monitoring is conducted for various purposes including: – To determine whether hazards to hearing exist – To determine whether noise presents a safety hazard by interfering with speech communication or the recognition of audible warning signals – To identify employees for inclusion in the hearing conservation program – To classify employees noise exposures for prioritizing noise control efforts and defining and establishing hearing protection practices OSH 367 W6 PPT1 Environmental Factors 30 Why measure Noise Levels – To evaluate specific noise sources for noise control purposes – To evaluate the success of noise control efforts OSH 367 W6 PPT1 Environmental Factors 31 Environmental Factors • Avoid Noise Annoyance: – Annoyance during thinking and communication tasks can arise at levels well below 80 dBA. An excess of noise will prove annoying even though the limit for damage to hearing has not yet been reached. • Rooms should not be kept too quiet – Although the aim is to reduce the noise levels to below a certain maximum the level should not drop below 30 dBA. OSH 367 W6 PPT1 Environmental Factors 32 Environmental Factors • Noise Reduction at the Source: – – – – Choose a low noise working method Use quiet machines Maintain machines regularly Enclose noisy machines OSH 367 W6 PPT1 Environmental Factors 33 Environmental Factors • Noise Reduction through Workplace Design and Work Organization – – – – Separate noisy from quiet work Keep an adequate distance from the source of noise Use the ceiling to absorb noise Use acoustic screens OSH 367 W6 PPT1 Environmental Factors 34 Environmental Factors • 4.1.4 Hearing Conservation: • Companies can resort to using PPE, HP is engineering controls are not feasible. • HP must be provided when noise levels are temporarily too high. • HP must be fitted to the worker – – – – Separate plugs Plugs with connecting cord Plug with neck band muffs OSH 367 W6 PPT1 Environmental Factors 35 Environmental Factors • Hearing Conservation Guidelines continued: – The NRR (Noise Reduction Rating) of HP is greatest with ear muffs… and are more convenient for frequent donning and doffing. – Perspiration, irritation, ease of use etc. all factors to be considered when selecting HP OSH 367 W6 PPT1 Environmental Factors 36 Environmental Factors • 4.2 Vibration: – Whole body vibration and hand-arm vibration (distinguish between) – Vibration is usually vertical – Vibration variables: (m/s), Hertz (Hz), exposure duration – Low frequency vibrations (<1 Hz) can produce seasickness – Vibrations between 4 and 8 Hz lead to chest pains, difficulties in breathing, low back pain and impaired vision OSH 367 W6 PPT1 Environmental Factors 37 Environmental Factors • Vibrations and user guidelines: • Avoid health and safety risks from vibration – Design machines to keep the vibration levels at any one time to below 0.5 m/s for whole body vibrations and 2.5 m/s for hand-arm vibration • Prevent shocks and jolts – Shocks and jolts with peak intensify more than higher than the vibration level will increase the total vibration stress and should be avoided OSH 367 W6 PPT1 Environmental Factors 38 Environmental Factors • 4.2.2 Vibration Prevention • Vibration can be prevented at the source – – – – Machine motors and can be a source of vibration Preventive maintenance (PM) Prevent the transmission of vibration If necessary, direct the measures at the individual OSH 367 W6 PPT1 Environmental Factors 39 Environmental Factors • 4.3 Illumination • Illumination can play a role in worker performance and wellbeing. Light intensity to perform the work must be sufficient. • Guidelines on user light intensity: – In determining the amount of the light needed distinguish between orientation lighting and normal workplace lighting and special lighting – Select a light intensity of 20-200 lux for orientation tasks – Select a light intensity of 200-750 lux for normal activities – Select a light intensity or 750-5000 lux for special applications OSH 367 W6 PPT1 Environmental Factors 40 Environmental Factors • 4.3.2 Guidelines on Brightness Differences: – Avoid excessive differences in brightness in the visual field – Limit the brightness differences between the task area itself the close surroundings and wider surroundings – See Table 4.3 – Perception by Humans of a few Luminance Ratios OSH 367 W6 PPT1 Environmental Factors 41 Environmental Factors • 4.3.3 Guidelines for the color of the light – Daylight is white light and has a color temperature of 5000 - 6500K. Light with color temperature (<5000 K) has more yellow and red and is perceived as warm – Avoid too cold and too warm colors for indoor lighting OSH 367 W6 PPT1 Environmental Factors 42 Environmental Factors • 4.3.4 Guidelines for Improving Lighting – – – – – – – Ensure good legibility of information Combine ambient and localized lighting Daylight can also be used for ambient lighting Screen sources of direct light Prevent reflections and shadows Use diffused lighting Avoid the flicker of florescent tubes OSH 367 W6 PPT1 Environmental Factors 43 Environmental Factors • 4.4 Climate • The indoor climate needs to satisfy several conditions if work is to be carried out in comfort. Four climatic factors: – – – – Air Temperature Radiant temperature of surfaces Air velocity Relative humidity OSH 367 W6 PPT1 Environmental Factors 44 Environmental Factors • Guidelines on Thermal Comfort – – – – – Allow people to control the climate themselves Adjust air temperature to physical demands of the task Avoid to o humid and too dry air Avoid radiating surfaces Prevent drafts OSH 367 W6 PPT1 Environmental Factors 45 Environmental Factors • 4.4.2 Guidelines on Heat and Cold • Hot and cold environment are not only uncomfortable; hot climates, such as near ovens, can be energetically very stressful to the heart and lungs. Cold and burns can injure parts of the body. – Avoid exposure to extremely hot or cold environment – Materials which must be touched should neither be too cold nor too hot OSH 367 W6 PPT1 Environmental Factors 46 Environmental Factors • 4.4.3 Climate Controls • Thermal comfort – Locate equally heavy tasks together in a room – Adjust the physical demands of the tasks to the external climate – Optimize air velocity – Prevent unwanted radiation – Limit the time spent in hot or cold environments OSH 367 W6 PPT1 Environmental Factors 47 Environmental Factors • 4.5 Chemical Substances • Chemical substances occur in the environment as liquids, gases, vapors, dusts, or solids. Some substances can cause discomfort or present a health hazard if inhaled or ingested or if they come into contact with skin or eyes. • Outcomes: – – – – Irritants Carcinogens Mutagens Teratogens OSH 367 W6 PPT1 Environmental Factors 48 TOXIC • May Produce Illness, Internal Damage, Possibly Death OSH 367 W6 PPT1 Environmental Factors 49 HEALTH HAZARD DATA • Acute - Large Enough Of A Dose To Cause An Immediate Response • Chronic - Health Effects Show Up After Repeated Exposure Over A Longer Period Of Time OSH 367 W6 PPT1 Environmental Factors 50 HEALTH HAZARD DATA • Routes Of Entry - Ingestion - Inhalation - Injection - Skin Absorption - Ethylene Glycol - Many Pesticides Inhalation Ingestion Injection Skin Absorption OSH 367 W6 PPT1 Environmental Factors 51 THRESHOLD • The Level Of Exposure To A Substance Where The First Effects Occur • Whether Or Not Ill Effects Occur Depends On - Properties Of The Substance - Dose - Route Of Entry - Susceptibility Or Resistance Of The Exposed Individual OSH 367 W6 PPT1 Environmental Factors 52 LETHAL DOSE {LD50} The Calculated Dose Of A Substance Which Will Cause Death In 50%Of the Animals Exposed C O N C E N T R A T I O N OSH 367 W6 PPT1 Environmental Factors LD5 LD5O 53 LD100 TARGET ORGANS Organs In Which A Substance Causes Damage As A Result Of Exposure, Including: Eyes Brain Lungs Heart Liver Kidneys Skin Reproductive Organs Blood OSH 367 W6 PPT1 Environmental Factors 54 EXCRETION OF TOXICANTS • Kidneys • Liver • Lungs • Body Secretions OSH 367 W6 PPT1 Environmental Factors 55 IRRITANTS • Aggravation Of Body Tissue Types Of Irritant Gases: Highly Soluble Irritant Gases • Affect The Upper Respiratory Tract - Ammonia Moderately Soluble Irritant Gases • Affect The Upper Respiratory Tract & Lung Tissue - Chlorine Low Soluble Irritant Gases • Affect The Lower Respiratory Tract - Nitrogen Dioxide OSH 367 W6 PPT1 Environmental Factors - Carbon Monoxide 56 ASPHYXIANTS Interferes with the supply of oxygen to the tissue Effects Possible Brain Damage Or Death OSH 367 W6 PPT1 Environmental Factors 57 • Simple Asphyxiants - Dilute The Concentration Of Oxygen In The Air Below Normal Levels Tissues Hemoglobin Circulation Oxygen Lungs • Chemical Asphyxiants - Prevent Uptake Of Oxygen By The Blood, Or Interfere With The Transport Of Oxygen From The Lungs To The Tissues Oxygen Hemoglobin Tissues OSH 367 W6 PPT1 Environmental Factors Circulation 58 Lungs SENSITIZER Repeated Exposure Produces An Allergic Reaction - Iodine - Nickel OSH 367 W6 PPT1 Environmental Factors 59 CORROSIVE Destroys Body Tissue On Contact - Bromine - Sulfuric acid - Sodium hydroxide OSH 367 W6 PPT1 Environmental Factors 60 CARCINOGEN Substance Which Causes Cancer, Abnormal Cells Or Tumors • Carcinogen - Proven To Cause Cancer In Man - Radiation • Suspect Carcinogen - Proven To Cause Cancer In Animals, But Not In Man - Formaldehyde - Saccharin OSH 367 W6 PPT1 Environmental Factors 61 MUTAGEN Substance Which Causes A Change {Mutation} In The Genetic Material Of A Living Cell OSH 367 W6 PPT1 Environmental Factors 62 TERATOGEN A Substance Causing A Birth Defect In The Developing Fetus, But Does Not Effect The Mother Or Father OSH 367 W6 PPT1 Environmental Factors 63 Environmental Conditions Chemical Compounds Physical Agents Biological Stress OSH 367 W6 PPT1 Environmental Factors 64 Air Contaminants • Vapors • Gases • Liquids – Mist – Fogs • Solids – Dust – Fumes – Fibers – Smoke OSH 367 W6 PPT1 Environmental Factors 65 Chemical Compounds Are used all over Can enter the bloodstream Hazard associated with these depends upon the solubility of the substance in body fluids OSH 367 W6 PPT1 Environmental Factors 66 Chemicals Liquids Chemicals which take the shape of their container Gases Formless fluids that occupy space Vapors Gaseous form of a substance that is usually a solid or a liquid, formed when the solid or liquid so evaporated OSH 367 W6 PPT1 Environmental Factors 67 Environmental Factors • 4.5.1 Guidelines on Chemical Substances • Most important guidelines on chemical substances are TLV’s (threshold limit values). These are official international limits for chemical substances in the air and are intended to prevent adverse health effects. OSH 367 W6 PPT1 Environmental Factors 68 Environmental Factors • Guidelines on Chemical Substances • Apply TLV’s or other limits as maxima for chemical substances in ambient air • Avoid carcinogenic substances • Avoid peak exposures • Exposure to mixtures of substances should be avoided • Always remain as far below the TLV as possible • Packages of chemicals should be labeled appropriately OSH 367 W6 PPT1 Environmental Factors 69 Environmental Factors • Avoid Carcinogenic Substances: – Certain airborne substances are known to cause cancer. Exposure to these substances must be avoided at all times. See Table 4.7 for a list of carcinogenic substances – International Agency for Research on Cancer (IARC) provides the research on carcinogenic substances OSH 367 W6 PPT1 Environmental Factors 70 Environmental Factors • Table 4.7 Random Selection of Chemical Substances That Are Considered to Induce Cancer • Substance Example of Use – – – – – Asbestos Benzene Chrome compounds Polycyclic hydrocarbon Vinylchloride Thermal insulation Solvent Pigment Component of tar Raw material for PVC OSH 367 W6 PPT1 Environmental Factors 71 Environmental Factors • Avoid Peak Exposures – Short term exposure to high concentrations of a chemical substance can affect health even if the TLV is, on average, not exceed the 8-hour limit. • Exposure to mixtures of substances should be avoided – TLV’s are established for purest form of a chemical • Always aim to remain as far below the TLV as possible – Continuing monitoring to make sure your Ee’s exposure is below the TLV • Packages of chemicals should be labeled appropriately – Supplier of chemicals are required to label their containers OSH 367 W6 PPT1 Environmental Factors 72 OSH 367 W6 PPT1 Environmental Factors 73 Environmental Factors • 4.5.2 Measures at the Source OSH 367 W6 PPT1 Environmental Factors 74 Environmental Factors • 4.5.3 Ventilation • Measures aimed at the exposure route should be taken whenever those directed at the source are inadequate. Measures directed at the transfer between the source and people (ventilation of the air). OSH 367 W6 PPT1 Environmental Factors 75 Environmental Factors • Chemical substances must be extracted directly at the source – If it is not possible to extract the release of chemical substances, then harmful substances should be extracted directly at the source. – Extracted air must be released to the without being cleaned – EPA laws restrict the permissible concentrations of chemical substances in exhaust air OSH 367 W6 PPT1 Environmental Factors 76 Environmental Factors • Table 4.8 Recommended Optimum Space and Air Change Nature of work – Very light – Light – Moderate – Heavy Vol./person 10m3 12m3 15m3 18m3 Fresh Air Supply Rates 30m3 hr3 35m3 hr3 50m3 hr3 60m3 h3 OSH 367 W6 PPT1 Environmental Factors 77 Environmental Factors • Ventilation: – Provide an efficient exhaust system – Pay attention to the effect on climate when designing air extraction and ventilation – Provide sufficient air changes OSH 367 W6 PPT1 Environmental Factors 78 Environmental Factors • 4.5.4 Measures at the Individual Level – – – – – Implement organized measures Provide and use PPE Use dust masks only for protections against coarse dust Use Protective Equipment Ensure high standards of personal hygiene OSH 367 W6 PPT1 Environmental Factors 79