A few points of difference between environmental and occupational health

Workers tend to be exposed to higher concentrations of exposure
Workers also tend to be exposed for longer duration of exposure
Workers tend to be healthier and younger than the members of the general public
Government agencies are different for Environmental health and occupational health issues

Classification of occupational and safety an health hazards

Safety hazards. -- From the source, uncontrolled transfer of energy (physical, chemical, electrical, thermal, kinetic, radiation) happens to vulnerable recipients. Example: electric shock, touching a hot plate, lead from battery units, radiation from Xray units, hit by a moving part in a car manufacturing unit, etc
Health hazards. -- Worker is exposed to a number of agents and develops disease
1. Chemical hazards. -- exposed to chemical agents at work and develops disease
2. Physical hazards. -- Noise, pressure, vibration, non-ionizing radiation
3. Biomechanical. -- Heavy weight lifting, repeated movements (carpal tunnel syndrome)
4. Biological. -- infection from infected syringes, HIV, Hepatitis B, etc
5. Psychosocial. -- Job loss, stress

What occupational hazards are common in NZ?

//Give the results of analyses from Neal Pearce's work

Epidemiology of occupational safety and health

How epidemiologists work
Epidemiologists analyze the disease, injury, or illness; profi le the patients; and look at circumstances or environments, habits, and motivations for healthy or unhealthy lifestyles. Epidemiologists may evaluate both ill and well individuals in an attempt to fi nd the reasons some people get ill and others do not. The usual starting point for this type of investigation is gathering data from ill and well individuals through surveys. Then an attempt is made to uncover the determinants of the disease and document locations and numbers of old and new cases. The data gathered from ill and well individuals who may have been exposed to the possible determinants allows the development of a rough hypothesis to explain causation. The epidemiologists now begin building a case defi nition . This case defi nition includes clinical and personal qualities of the people experiencing the health event under investigation.
Public health surveillance systems
Occupational health surveillance
Start with a problem statement: disease, exposure, or anything in the workplace for which you need good data. 
Step two: identify the risk factor: microorganism, cigarette smoking, faulty machinery in the workplace, 
Step three: find out what works to solve the problem

History of occupational health

Hippocrates in 5th century BC in his work, airs, waters, and places wrote