Occupational Health Undergaduates Edited
This document was uploaded by user and they confirmed that they have the permission to share it. If you are author or own the copyright of this book, please report to us by using this DMCA report form. Report DMCA
Overview
Download & View Occupational Health Undergaduates Edited as PDF for free.
More details
- Words: 960
- Pages: 21
PREVENTION OF OCCUPATIONAL HAZARDS 1
Prevention of work-related Disorders :
A. Identification of risks Through:. 1.
Predict the risk before it occurs: * New compounds and processes: by toxicological tests * Established process: Three methods: a. Clinical observation on the exposed. One or more exposed may be affected. b. Epidemiological studies c. Environmental monitoring. 2
B.
1.
Introducing Preventive Measures
Elimination or diminution of Risk:
* Substitution * Redesign of process * Improve work methods 2. Total enclosure of process 3. Segregation: Reduce number exposed. 4. Ventilation: Dilution & Exhaust. 3
B.
Introducing Preventive measures (con)
5. Suppression of dust 6. Good House Keeping 7. PPE, reduction of exposure time, barrier creams, immunization, personal hygiene. 8. Training for health & safety: From the worker to the top manager 9. Maintaining control: Environmental and Health Monitoring. 4
OCCUPATIONAL HYGIENE
Concept and categories of TLV. NOISE. Hearing conservation Programs. 5
Measurements of Workroom Airborne Contaminants
Concept of TLV: Threshold limit values (TLVs) are limits (guidelines)for concentrations of substances in the work environment to which workers are allowed to be exposed day after day without adverse effects on the health of the majority of them. 6
Concept of TLV:
How derived?
1. Industrial experience 2. Experimental and human studies 3. A combination of all when possible. The TLVs vary from substance to substance. Consideration is also given to the possibility of the substance entering the body through the skin including the mucous membranes. 7
CATEGORIES OF THE TLV
THREE CATEGORIES I. TLV – TWA: Refers to time-weighted average concentrations to which workers can be exposed for 8 hours a day and 40 hours a week and it is believed that nearly all workers may be repeatedly exposed day after day without adverse effects 8
CATEGORIES OF THE TLV II. TLV – STEL: The concentration to which workers can be exposed continuously for a short period of time without suffering from: 1.. irritation, 2.. chronic or irreversible tissue change, or 3.. Narcosis of sufficient degree to increase the likelihood of accidental injury, impair self-rescue or materially reduce work efficiency, and provided that the daily TLV – TWA also is not exceeded.
9
CATEGORIES OF THE TLV
II. TLV – STEL (CON): It is also required that: The exposure should not be for more than 15 minutes and that the TWA is not exceeded Exposures at the STEL should not be repeated more than 4 times per day There should be at least 60 minutes between successive exposures at the STEL. 10
CATEGORIES OF THE TLV
III. TLV – C (Ceiling): The concentration that should not be exceeded even instantaneously. All irritant and fast acting substances have this ceiling value.
11
CATEGORIES OF THE TLV
Mixtures: Exposure to mixtures needs special attention. These have a special formula when they act upon the same body system. Their combined effect is given primary consideration (that is, the effect is considered additive). Some substances act independently on different organs. In such cases the formula is analyzed differently. Synergistic or potentiation may also occur. This again is treated differently. 12
NOISE Definition: Noise is unwanted sound. Three types of noise: 1. Impact (single impulses of short duration at regular or irregular intervals), 2. intermittent, 3. Steady – state (continuous). Noise is usually a combination of frequencies (called spectrum).
13
NOISE HEALTH EFFECTS OF NOISE I.Non-auditory effects: Interferes with speech and communication Annoyance Reduces output and efficiency and causes fatigue Disturbs sleep and causes stress
14
NOISE
II. Auditory effects: Acoustic reflex have some (but limited) degree of protection against acoustic trauma arising from loud noise. Stapedius and tensor tympani muscles contract in response to loud noise. This results in less energy transmission to the sound receptors in the inner ear. Muscle fatigue might occur Delay in response to sudden sounds 15
NOISE
Auditory fatigue causes a temporary shift in threshold of hearing resulting in a decrease in hearing: called Temporary Threshold Shift (TTS). Fatigue is greatest at 4000 Hz (4KHz). Recovery might take several hours within 16 hours it is usually over. Tinnitus may be associated with this 16 shift.
NOISE
If recovery does not occur within 16 hours, the exposed is developing noiseinduced hearing loss (NIHL) and this is a permanent state (Permanent Threshold Shift [PTS]. First sign of NIHL is a slight impairment of hearing as a dip in the 4000 Hz range. Later this expands to both sides of this range to include 3000 – 6000 Hz. This is the characteristic of NIHL. 17
NOISE
Worker might not be aware of hearing defect until the speech frequencies are involved (500 – 2000 Hz). Impulse noise is most dangerous form (causes sudden loss of hearing). 18
Hearing conservation Programs
Reduction of noise at source: machine design, enclosure, silencing exhaust systems. Limit noise exposure: reduce duration of exposure, increase distance between source and the listener, use of ear protection, enclose the operator of the noisy machine. Ear protection: Ear muffs are more effective than ear plugs. Cotton wool: extremely poor protector. 19
Hearing conservation
Routine audiometry to be compared with pre-placement audiometry. Health education: About hazards of noise, use of ear protection devices. Legislation: employers to make noise assessment, protect workers, and pay for audiometry. 20
TLVs for noise (for the unprotected ear) Frequency {dB (A)} 80
Maximum allowed exposure time (hours) 16
85
8
90
4
95 100
2 1
105 110 115
1/2 1/4 1/8 th.
NO EXPOSURE TO NOISE ABOVE 115 dB without ear protection. 21
Prevention of work-related Disorders :
A. Identification of risks Through:. 1.
Predict the risk before it occurs: * New compounds and processes: by toxicological tests * Established process: Three methods: a. Clinical observation on the exposed. One or more exposed may be affected. b. Epidemiological studies c. Environmental monitoring. 2
B.
1.
Introducing Preventive Measures
Elimination or diminution of Risk:
* Substitution * Redesign of process * Improve work methods 2. Total enclosure of process 3. Segregation: Reduce number exposed. 4. Ventilation: Dilution & Exhaust. 3
B.
Introducing Preventive measures (con)
5. Suppression of dust 6. Good House Keeping 7. PPE, reduction of exposure time, barrier creams, immunization, personal hygiene. 8. Training for health & safety: From the worker to the top manager 9. Maintaining control: Environmental and Health Monitoring. 4
OCCUPATIONAL HYGIENE
Concept and categories of TLV. NOISE. Hearing conservation Programs. 5
Measurements of Workroom Airborne Contaminants
Concept of TLV: Threshold limit values (TLVs) are limits (guidelines)for concentrations of substances in the work environment to which workers are allowed to be exposed day after day without adverse effects on the health of the majority of them. 6
Concept of TLV:
How derived?
1. Industrial experience 2. Experimental and human studies 3. A combination of all when possible. The TLVs vary from substance to substance. Consideration is also given to the possibility of the substance entering the body through the skin including the mucous membranes. 7
CATEGORIES OF THE TLV
THREE CATEGORIES I. TLV – TWA: Refers to time-weighted average concentrations to which workers can be exposed for 8 hours a day and 40 hours a week and it is believed that nearly all workers may be repeatedly exposed day after day without adverse effects 8
CATEGORIES OF THE TLV II. TLV – STEL: The concentration to which workers can be exposed continuously for a short period of time without suffering from: 1.. irritation, 2.. chronic or irreversible tissue change, or 3.. Narcosis of sufficient degree to increase the likelihood of accidental injury, impair self-rescue or materially reduce work efficiency, and provided that the daily TLV – TWA also is not exceeded.
9
CATEGORIES OF THE TLV
II. TLV – STEL (CON): It is also required that: The exposure should not be for more than 15 minutes and that the TWA is not exceeded Exposures at the STEL should not be repeated more than 4 times per day There should be at least 60 minutes between successive exposures at the STEL. 10
CATEGORIES OF THE TLV
III. TLV – C (Ceiling): The concentration that should not be exceeded even instantaneously. All irritant and fast acting substances have this ceiling value.
11
CATEGORIES OF THE TLV
Mixtures: Exposure to mixtures needs special attention. These have a special formula when they act upon the same body system. Their combined effect is given primary consideration (that is, the effect is considered additive). Some substances act independently on different organs. In such cases the formula is analyzed differently. Synergistic or potentiation may also occur. This again is treated differently. 12
NOISE Definition: Noise is unwanted sound. Three types of noise: 1. Impact (single impulses of short duration at regular or irregular intervals), 2. intermittent, 3. Steady – state (continuous). Noise is usually a combination of frequencies (called spectrum).
13
NOISE HEALTH EFFECTS OF NOISE I.Non-auditory effects: Interferes with speech and communication Annoyance Reduces output and efficiency and causes fatigue Disturbs sleep and causes stress
14
NOISE
II. Auditory effects: Acoustic reflex have some (but limited) degree of protection against acoustic trauma arising from loud noise. Stapedius and tensor tympani muscles contract in response to loud noise. This results in less energy transmission to the sound receptors in the inner ear. Muscle fatigue might occur Delay in response to sudden sounds 15
NOISE
Auditory fatigue causes a temporary shift in threshold of hearing resulting in a decrease in hearing: called Temporary Threshold Shift (TTS). Fatigue is greatest at 4000 Hz (4KHz). Recovery might take several hours within 16 hours it is usually over. Tinnitus may be associated with this 16 shift.
NOISE
If recovery does not occur within 16 hours, the exposed is developing noiseinduced hearing loss (NIHL) and this is a permanent state (Permanent Threshold Shift [PTS]. First sign of NIHL is a slight impairment of hearing as a dip in the 4000 Hz range. Later this expands to both sides of this range to include 3000 – 6000 Hz. This is the characteristic of NIHL. 17
NOISE
Worker might not be aware of hearing defect until the speech frequencies are involved (500 – 2000 Hz). Impulse noise is most dangerous form (causes sudden loss of hearing). 18
Hearing conservation Programs
Reduction of noise at source: machine design, enclosure, silencing exhaust systems. Limit noise exposure: reduce duration of exposure, increase distance between source and the listener, use of ear protection, enclose the operator of the noisy machine. Ear protection: Ear muffs are more effective than ear plugs. Cotton wool: extremely poor protector. 19
Hearing conservation
Routine audiometry to be compared with pre-placement audiometry. Health education: About hazards of noise, use of ear protection devices. Legislation: employers to make noise assessment, protect workers, and pay for audiometry. 20
TLVs for noise (for the unprotected ear) Frequency {dB (A)} 80
Maximum allowed exposure time (hours) 16
85
8
90
4
95 100
2 1
105 110 115
1/2 1/4 1/8 th.
NO EXPOSURE TO NOISE ABOVE 115 dB without ear protection. 21
Related Documents
Occupational Health Undergaduates Edited
November 2019 12
Occupational Health
May 2020 15
Occupational Health And Safety
May 2020 28
Occupational Environment: And Health
July 2020 20
Occupational Environment: And Health
July 2020 24