Temperature, Light, Noise

8/13/2019 Temperature, Light, Noise

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Environmental Conditions in the

Workplace


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Factors a worker is exposed to that puts him at

risk/injury:

Heavy vibration

Extreme temperatures

Frequent lifting, carrying, and handling loads

Improper lighting conditions

Extreme noise

working more than 8-hour days

may result in work-related musculoskeletaldisorders, or MSDs


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Thermoregulation

human body regulates temperature by

keeping a tight balance between heat gain andheat loss

temperature at rest varies between 36.5 and

37.5Celsius

temperature is regulated by the hypothalamus

(in the brain)

Heat can be lost through the processes ofconduction, convection, radiation, and

evaporation


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Temperature Guidelines

OSHA recommends that

the employers keep the

thermostat between:

Temperature

68-76oF (Winter)

73-79oF (Summer)

Relative Humidity

30-50% (Winter)

40-65% (Summer)


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Thermostat considerations:

Poor thermostat location: keep away from

copy machines, perimeter walls and

sunlight.

Thermostat Dead Band: Wide dead bands

results in large temp. fluctuations

Radiant Heat Gain/Losses: Utilize separate

thermostats for perimeter locations

Temperature Stratification: temp. near the

ceiling is warmer than at floor level


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Heat Stress Disorders

Heat hyperpyrexia (heat stroke):

thermoregulation fails, temp. exceeds 41 C

Heat exhaustion: thermoregulatory strain

combines with cardiovascular strain

Heat syncope: fainting due to inadequate

venous return

Heat hyperventilation: excessive loss of

Carbon Dioxide

Prickly heat: superficial skin rash associated

with excessive sweating


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Humidity Related Disorders High Humidity: RH exceeding 50-60% promotes

mold growth, dust mites, and musty odors that cancause allergies and asthma

Recommendation: Dehumidifiers, heat and ventilation

reduce humidity levels particularly in basements and

crawl spaces

Low Humidity: RH below 30-40% can dry the eyes,

nose and respirator passages & susceptible to

respiratory infections and colds

Recommendation: cleaning of water in the holding tank,

cleaning the humidifier every 3 days & using distilled

water in the tank instead of tap water


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Ventilation

purpose is to provide fresh air and to remove

accumulated noxious gases and contaminants

American Society of Heating, Refrigerating,

and Air Conditioning Engineers (ASHRAE)

provides minimum ventilation rates and indoor air qualitythat will be acceptable to human occupants and are

intended to avoid adverse health effects

outdoor air must be supplied to each room

within the facility range from 15 to 60 cubic

feet per minute/person


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Ventilation Problems & Solutions

System design:

Intermittent air flow: follow minimum ventilation rates

Distribution of air: proper placement of partitions

Building supply and exhaust locations: placing supply vents

away from outdoor sources of pollution

Proportion of Outdoor Air:dilute contaminantsby fresh supply of air

Periods of Operation: HVAC systems must operatelonger than occupants stay in building

Maintenance: cleaning HVAC ducts to preventmicroorganism growth


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IDPH: Illinois Department of Public Health

ASHRAE: American Society of Heating, Refrigerating, and Air Conditioning Engineers

OSHA PEL: Occupational Safety Health Administration; Permissible exposure limitsACGIH TLV: American Conference of Governmental Industrial Hygienists; Threshold Limit Values


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Worksite Lighting

OSHA standard1926.56 established

minimum lighting

requirements in foot-

candles:

the amount of

illumination produced

by a candle from 1foot distance and

abbreviated ftc


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Balance of surface luminances

Contrast: the luminance contrast b/w 2

surfaces is given by the difference b/w the

luminances of the brighter & dimmer surface

exposed as a % of the brighter

Contrast= (Lbright - Ldark)/ Lbright

Glare: occurs when there is

an imbalance of surface or

object luminances- brighter

sources exceeding the level to

which the eye is adapted


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Lighting design considerations:

1. Suitable level of illumination

2. Balance of surface luminances

3. Avoidance of glare4. Uniformity of lighting

5. Colour rendering properties of light


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Lighting should beindirect and adequate

Not too much light, orit may cause a glare,headaches and eye

fatigue If there is a glare on

your eyes as you work,

use glare screens oncomputers, oradjustable blinds atwindows


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Since 2004, nearly 125,000 workers have suffered

significant, permanent hearing loss. In 2009 alone, more than 21,000 hearing loss cases

were reported.

- Bureau of Labor Statistics

Neither surgery nor a hearing aid can help correctpermanent hearing loss.

Short term exposure to loud noise can also cause atemporary change in hearing. These may go awaywithin a few minutes or hours after leaving the noisyarea.

However, repeated exposures to loud noise can lead topermanent tinnitus and/or hearing loss.

Noise Induced Hearing Loss (NIHL)


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Psychosocial aspects

physical and psychological stress, reduce

productivity, interfere with communication and

concentration, and contribute to workplace

accidents and injuries by making it difficult to hearwarning signals

Tinnitus

experienced as noises or ringing in the ears or

head when no such external physical noise is

present due to inner cell damage

Blood pressure

Blood pressure increases in noisy environment

Noise hazards


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Occupational Exposure Limits

define a workers maximum permitted daily

exposure to noise without hearing protection

Lex is the workers level of total exposure to

noise in dBA, averaged over the entire work

day Should not exceed 85 dBA for an 8-hour period

eg,. a worker exposed to 88 dBA for 4 hours or 91

dBA for 2 hours would be exposed to 85 dBALex(an exposure equivalent of 85 dBA for 8 hours)


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Reverberation is the inter-reflection of sound

waves inside a room

The sound emanating from a source reachesthe listener both directly & after being

reflected off the walls & other objects


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Noise exposures

Recordable &

reportable hearingloss is referred to

under OSHA in 29

CFR 1904, at 85dB orhigher


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Problem areas & control methods

Fans: use larger fans at lower speed

Muffling: pipe the air away from the operator Part ejection: mechanical ejectors are usually

quieter

Pneumatic tools: hydraulic/electricequivalence are quieter

Impact tools: fitting of resilient bumpers

Hydraulic reticulation: avoid sudden drops inpressure

Vibration: regular maintenance & replacementof worn parts


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Several approaches to noise control can be

identified:

Eliminate the threat to hearing by redesigning themachine or using a less noisy machine

Remove personnel from the noisy environment

Protect personnel by issuing ear-plugs or

muffs or build an acoustic refuge

Noise insulation

Porous & light-weight sound absorbing materials

such as screens, carpets, curtains &tiles

Active noise control at lower

frequencies in a periodic or cyclic nature


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THANK YOU

Amrita Ganguly (1)

Madhusmita Boro (11)

Madhurima Saha (12)

Sakshi Agarwal (21)

Soutrik Dey (23)

Jacky Johnson Kisku (26)

Documents

Temperature, Light, Noise