What are Hazardous Substances?
Are defined as chemicals capable of causing adverse health effects to people.
Examples include benzene, asbestos, hydrochloric acid. Look for the Risk and
Safety Phrases on the label, SHOC Card or MSDS. Ideally the MSDS will stipulate
whether the chemical is hazardous or not.
What are Heavy Metals?
Mercury is a trace component of geologic hydrocarbons including coal, crude
oil and natural gas.
Mercury in natural gas processing systems and above certain concentrations
can deposit in, and thus contaminate, equipment, treatment fluids and process
waste streams. Maintenance and inspection activities, therefore, must contend
with mercury contamination from a health and safety standpoint and such
activities also must be structured to avoid escape of mercury into the
environment.
What are Occupational Exposure Limits?
Occupational Exposure Limits refer to airborne concentrations of chemical
substances to which nearly all workers may be repetedly exposed, day after day,
over a working lifetime, without adverse health effects.
There are three categories of exposure limits:-
- Time-Weighted Average (TWA)
- Short-Term Exposure Limit (STEL)
- Peak or Ceiling Limit
The exposure limits PDO adopts are taken from the most current edition of the
ACGIH Threshold limit values for Chemical Substances. Where Shell adopts a more
stringent exposure limit, these values will be included in the SHOC cards.