Many chemicals in common use have been identified as extremely hazardous, and represent serious health risks to personnel in the plants where they are manufactured, processed, stored or transported. All such chemicals are governed by clearly defined exposure limits, so an accurate measurement provides an early warning device to the worker when exposed to excessive levels. Data logging and storing information for proof of compliance to the standards used is also essential.
Among the chemicals in industrial use are vinyl chloride, ethylene oxide, styrene, polyols, acrylates and solvents, together with a host of other VOCs and non VOCs such as H2S. Many of these are produced as intermediate products in the manufacture of other chemicals. Vinyl chloride, for example, is produced as the precursor of PVC.
Known to cause liver cancer, vinyl chloride must be carefully monitored for ambient concentrations during its manufacture, during its transport and during the manufacture of PVC. Ethylene oxide is another toxic chemical an known carcinogen, used as a sterilisation gas for medical products.
Not all of these compounds represent the same health hazards and not all carcinogenic links have been proven. Thus, depending on the particular chemical, maximum exposure levels might be set at anything from a few hundred parts per million (ppm) to under 10 parts per billion (ppb). The more dangerous these chemicals are, the smaller the concentrations that are permitted for exposure.
Legislation demands the effective monitoring of these compounds in the industrial environment to provide early warnings on any leaks or chemical build-up. This is essential both to protect personnel at the plant and to prevent leakage that could harm the environment and the wider populace.
For plant personnel in particular, it is believed that many cases of ill health are almost certainly due to inhaling toxic vapours. The question, then, is how best to monitor the areas in which people are working to provide the best and most complete picture of the hazards present.
Any location where the chemicals are manufactured, stored or used should be regularly monitored. This can be performed with hand-held instruments, or with fixed-in-place detectors that can send the information directly to a control system. A plant survey might identify possible sources of leaks and emissions that should be monitored with hand-held instruments. Further, the use of hand-held instruments should be used to regularly sweep for ‘hot spots’ or high concentrations.