TxSharon, over at Bluedaze has posted some hand-written notes obtained from Texas Commission on Environmental Quality (TCEQ) regarding that Phase IV air quality study that already has them in hot water.
What I find most interesting is this:
- Where [sic] respirator if needed, but if media is around, wait to take samples.
- If camera around w/respirator, email Terry Clawson.
In other words, you wouldn't want to alarm the public by being seen having to wear a respirator if the air should be really bad.
There's also this note:
* Opening QC each day
- Benzene needs to pass
The phrase "Benzene needs to pass" could be disturbing if the meaning is "make it pass". Hopefully this is just a note about machine calibration with a reference standard or something like that. (See updates below on this.)
At any rate, I'm further reassured that the decision of my neighborhood association to conduct and pay for our own testing is the right decision.
Update: 1:31 PM - We just spoke with TCEQ spokesman Terry Clawson, who was listed in the document. Clawson says that the statement regarding Benzene was indeed related to quality control, and referred to calibrating the equipment. With regards to the staff wearing respirators, we asked if TCEQ had thought the air would have been bad enough to require respirators. Clawson responded "absolutely not". Clawson was going to look into the QC procedures for the equipment, such as the Toxic Vapor Analyzers (TVAs) and get back to us.
Update #2 (6/16/2010):
Clawson got back to us this morning with a fuller explanation of the benzene comment:
The comment was in reference to the gas chromatograph van-mounted analyzer. Here's some technical data:
The comment that "Benzene needs to pass" was written with the understanding that the benzene daily quality control (QC) analyses must pass our real-time GC (RTGC) acceptance criteria. The criteria are listed in Standard Operating Procedure AMOR-001 and for benzene is as follows:
- The relative percent error (accuracy) must between the QC run and the theoretical concentration must be between 80 percent and 120 percent
- The relative percent difference (precision) between the two QC runs must be less than or equal to 20 percent.
I'm glad to see that this was nothing sinister. I didn't think it would be. But I am a bit concerned about the tolerances above, not just with accuracy, where a certain amount of deviation is expected, but with the precision. Although I'm no scientist, I would imagine that allowing a 20% difference between one test and another on the same machine would be a bit much, and would call into question the accuracy of results. I'll be interested to know if any of our readers has experience with precision figures for these types of instruments.