Occupational Environment: And Health

Occupational Environment and Health Dr. Zhang Qiao Department of Toxicology College of Public Health Zhengzhou University 25-10-2006

Part 1. Occupational Environment Part 2. Practice of Occupational Medicine

Part 3. Disease Associated with Exposure to Occupational Factors

Occupational Impariment  

occupational injuries occupational disorders

workrelated diseases

occupational diseases

Classification of Occupational Hazards

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Chemical factors

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Physical factors

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Biological factors

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Ergonomic and Psychosocial factors

Physical hazards 

Microclimate:

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Abnormal air pressure

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Noise and vibration

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Radiation

microclimate It include some environmental factors: Air temperature in workplace Air humidity Air speed Thermal radiation

Part 3. Disease Associated with Exposure to Occupational Factors

3.1 Disease Associated with Exposure to Microclimate

The organism must maintain balance between heat generation (eg. metabolism ， ＋ M) ， heat acceptance and heat elimination(eg. evaporation ，－ E). heat balance Heat generation heat acceptance

heat elimination

Heat exchange between the organism and environment takes place in the form of convection ( ±C), radiation (±R) , evaporation ( － E).

Heat exchange between the organism and the environment may be expressed as following way: M ±C ±R － E = 0 ＋ M—metabolism (produce heat) ±C— convection (increase or reduce heat) ±R— radiation (receive or reduce heat) － E — evaporation (reduce heat in organism)

The formula show that if organism maintain a stable temperature, the right of formula should be equal to the left. If environmental temperature is too high, heat balance between heat generation and heat elimination is broken , the organism may produce thermal disorder.

If the the right of formula is not equal to zero, organism will be a state of heat strain. The heat will be store up in the body, and organism will show hyperthermia.

Depending on the thermal load and exposure time, the organism may react in different ways. The most severe thermal disorder are the illnesses such as : • heat stroke, • heat syncope, • heat cramp • heat exhaustion.

Standardization of measurements of the heat load and the thermal state is based on the principle of stress analysis of thermal regulation.

The exposure limits for permissible microclimatic condition adopted in various countries are based on measurements of a correlation between the intensity of the factors to which the organism is exposed and the thermal state of the organism with regard to the workload and individual characteristics.

3.2

Disease

Associated with Exposure to Noise

3.2 Disease Associated with

Exposure to Noise 3.2.1 Concept of Noise: Any unwanted sound or combination of sounds are called Noise.

3.2.2 The physical parameters in characterizing diverse effect of noise on organism. 

Intensity

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Frequency spectrum

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Duration of exposure

Intensity of noise is determined by the amplitude of acoustic pressure, which represents the difference between alternating rises and falls in acoustic vibrations compared with atmospheric pressure. The noise levels are expressed in logarithmic unit or decibels (dB).

Frequency spectrum The hearing organ in human is more sensitive to the noise of high frequency (such as 4000-8000Hz) than that of low frequency.

Duration of exposure The long the workers are exposed to noise, the more the hearing organ disorders.

3.2.3. The units of noise level---dB Because the levels of acoustic pressure within hearing range may vary millions of time , in order to reduce the measurement scale, the noise levels are expressed in logarithmic units of acoustic pressure or decibels(dB). It is called Sound Pressure Level (Lp). The Lp’s unit is dB.

Lp ( dB ) = 20 log 10 P/ P0 P ---sound pressure determined P0--- hearing threshold sound pressure at 1000Hz

dB(A)----the Lp was determined by simulating the function of hearing organ in human which is more sensitive to the noise of high frequency ( such as 4000-8000Hz) than that of low frequency. eg. General talk: 60-75 dB(A) Truck Loaded: 80-90dB (A) Plane taking off : 110-120 dB(A)

3.2.4 The Influence of Industrial Noise on Organism 1. Hearing impairment, noise-induced deafness specific action Hearing loss: temperary threshold shift, TTS permanent threshold shift, PTS Occupational deafness

3.2.4 The Influence of Industrial Noise on Organism 1. Hearing impairment, noise-induced deafness specific action 2. Neurobehavioral disturbance 3. Cardiac symptom, Nonspecific action ECG change 4. Circulatory system disturbance 5. Hypertension

The major features of occupational hypoacusis are initial loss of the hearing function in the region of 4000~8000Hz with further spreading into medium and low frequencies.

The major features of occupational hypoacusis (tip)

In assessing hearing function, the hearing changes normal for the subject’s age should be taken into account.

3.2.4. The Limit

85 dB (A) for 8 hours.

Persona l protect