Top Ten Errors to Avoid in Industrial Hygiene:

1. Workin’ 9-5:
   This error occurs when the most important exposure is missed because it occurs outside the "normal" work day.
2. Seeing is Believing:
   This error occurs when samples are taken for substances that can be seen but are not air contaminants, for example, metals in machine tool operations are obvious but too large to present a hazard.
3. Seeking the invisible to accomplish the impossible:
   Air samples are usually not necessary to identify the cause of dermatitis. Allergic or irritant contact dermatitis usually occur from direct skin contact rather than inhalation.
4. "You should have been here yesterday":
   The most frequently heard comment in industrial hygiene. Sometimes, “yesterday” really was very different and exposure was worse. Sometimes, it is perception that the day before was different. The answer to this is documentation. If variables are noted — even if it isn’t a worst case day — it is still valuable information.
5. The Low Bid:
   Some sampling errors occur due to an attempt to save on laboratory analysis costs by limiting the number of samples:
   • Running a single charcoal tube for eight hours when the time limit is usually one hour.
   • Missing a short term overexposure.
   • Taking too few samples to be truly representative of exposure.
   The number of samples taken should reflect a sampling strategy based on worst case or representative exposures.
6. Rotameter Reliance:
   A rotameter or small hand held portable air flow meter can be used to monitor flow rates but initial pump set up and flow rate measurements at the end of the sampling period should be taken using a primary device: a bubble meter or other primary air displacement device. When exposure limits are very low, for example, 5.0 microns for hexavalent chromium, it is important to be as accurate as possible with the pump calibration.
7. OSHA Compliance Reliance:
   Outdated OSHA Permissible Exposure Limits should not be the only limits used to gauge exposure risk. Most of OSHA’s exposure limits were adopted in the late sixties from the American Conference of Industrial Hygienists (ACGIH) recommended Threshold Limit Values from 1968. Exposure limits recommended by ACGIH or the National Institute for Occupational Safety and Health (NIOSH) should also be considered.
8. Pump and Circumstance:
   Sometimes a sampling strategy is based on how many pumps are available. The sampling strategy should be based on the questions you want answered.
9. The MSDS is the Last Word:
   A sampling strategy should not be based only on Material Safety Data Sheet (MSDS) information. Some chemical contaminants, not listed on the MSDS because they are present at less than 1% or less than 0.1% as a carcinogen, can still represent an exposure issue. It is important to recognize where these contaminants may be present.
10.  Carbon Dioxide—No Problem!!
    Overlooking or not recognizing decomposition products can result in missing important air contaminants. The MSDS often, optimistically, lists carbon dioxide as the “Decomposition Product” but not everything makes it that far. There is often incomplete combustion at low temperatures which can result in exposure to contaminants like formaldehyde or polychlorinated biphenyls (PCBs) which are not listed on the MSDS.