How about the "severity"?
OK, here is a scientific statement of risk: "About 1 out of 750
unprotected workers with high exposure to vinyl chloride develop angioscarcoma
(a rare liver cancer)." Although I was not very specific about what
I meant by "unprotected" and "high," it states the
probability and severity of a harm. (I guessed at the 750, the rest is
The word hazard is a very general term
meaning some unsafe or dangerous, situation or thing. We use the term
"hazard" and its adjective "hazardous" frequently,
but neither are precise and should be avoided in technical descriptions
How about skydiving. Let's say the chances of being hurt while skydiving
are: one minor injury per 500 jumps and one serious injury or death per
10,000 jumps. Is this a statement of risk?
. Before you click on the little buttons with the "?" you
should try to formulate an answer to the question.. (I made
up those numbers too, but let's assume they are true.) Now would you describe
skydiving as "safe?" Here we may
not agree. Thousands of skydivers pay lots of money to jump out of airplanes.
They admit there is a chance of them getting hurt, but enjoy the exhilaration
of falling thousands of feet, and feel the risk is well worth it. They
describe the sport as "safe." Do you? (I don't.)
Think about it. We agree on the risks of skydiving, but do not
agree if it is "safe." That is often the case. Why? The
definition of "safe" is,
Absence of unacceptable risks.
(Or its equivalent, the presence of only acceptable risks. You can restate
that defining "unsafe" similarly.)
So now, when you read or hear that something is "safe," you
should immediately ask yourself
. Again, safe and unsafe are words we often use, but they
are very subjective.
While we are defining, let us contrast the words "injury" and "disease."
An injury usually occurs at a definite
time and place. Most injuries are caused by a sudden release of energy.
There is a clear cause and effect. A worker falls down and breaks her
arm. The fall happened at a particular time and place. The fall is a transfer
of potential energy, the height of the body's center of mass over the
ground, into kinetic energy of the falling body.
A disease is ill health.
The time a disease is acquired is often vague. Many diseases have periods
of incubation or latency. There is often a lack of clear cause and effect.
In the field of industrial health and safety, safety
is the prevention of injuries and industrial hygiene
is the prevention of (workplace caused) disease.
So the term "industrial hazard" might include threats of injury
and/or disease. For example: gasoline is both a safety hazard (fire) and
a health hazard (narcosis, skin irritation, and perhaps cancer).
Next. Last Slide Learning