This explains it,
http://www.epa.gov/athens/learn2model/part-two/onsite/doc/Indoor Air Unit Conversions.pdf
as does this
http://www.ccohs.ca/oshanswers/chemicals/convert.html
I am going to go with Dr. F and the testing labs remarks on Click Bang, for my belief that the standard of being able to test to the precision of 5 ppm in liquid form is good. I also see that Dr. F did the math and converted the NOISH standards to apply to his tests.
as I show here:
http://gfn.net.co/downloads/2014/posters/122 Farsalinos - DA_AP.pdf
I am pretty much not going to think otherwise, at this juncture, as it wouldn't be prudent to do so. If a vendor provides data that
the end liquid has lower than 5 ppm, I am going to go with, its effectively zero.....and zero on a very very tough grading scale. If I were hear Dr. F or a testing lab say otherwise, I would consider that.....but geez they already said it the other way, I doubt it will happen.
YMMV, but this is distance, and its not going to change.
YES - Let's dig into this, starting with Dr. Farsalinos' peer-reviewed, published paper:
title: Evaluation of electronic cigarette liquids and aerosol for the presence of selected inhalation toxins
abstract: The purpose of this study was to evaluate sweet-flavoured electronic cigarette (EC) liquids for the presence of diacetyl (DA and acetyl propionyl (AP), which are chemicals approved for food use but are associated with respiratory disease when inhaled.
Major Observation #1: The actual science that has been peer-reviewed and published concerns only the presence of these chemicals. PERIOD. That it the entire scope of the paper. He did NOT recommend a 5 ppm testing limit for eliquid (or anything else) in this paper. This is very important to understand. His paper is just measures. Everything else he has discussed, suggested, recommended, theorized, and computed is entirely OUTSIDE THE SCOPE OF HIS PUBLISHED RESEARCH. If you look at the poster Tom links to above, you see no mention of any of this. I do not dispute or doubt Dr. F's published research.
Major Observation #2: The first couple links Tom posted above do not "explain" anything - they are standard calculators that convert between measured ppm of a particulate in AIR to the scientific standard used in air quality measures, which is units per cubic volume of air. If you use the second one, enter 5ppm, select diactyl, and you see 17.605 mg/m^3. This is just a simple conversion based on the molecular weight of diacetyl. It means this: 5ppm of diacetyl IN THE AIR is 17.605 milligrams of diacetyl per cubic meter IN THE AIR. And vice-versa of course. Different matter (diacetyl, ap, or any other substance) has different molecular weight, so when it is a given number of parts of something, you use the substance's molecular weight to figure out the mass of that substance per unit of volume. So we know 5ppm of diacetyl "weighs" 17.605 mg/m^3. Very simple.
The Crux of the Matter: From this point on (during interviews and so on), Dr. Farsalinos has engaged in conjecture. First he took NIOSH's recommended 8 hour/day, 5 day/week exposure limit (5ppb) and mathematically computed total weight of the molecules of maximum exposure level per day allowed without a full-face respirator. He assumed steady exposure with every breath over the course of a 12 hour vaping day. He completely ignored NIOSH's other published limits for maximum 15-minute exposure. Then he made numerous assumptions about vaping equipment, vapers' habits, percent of flavoring used in e-liquid (and so on) to arrive at a suggested 5ppm measure in finished e-liquid as a "reasonable figure." His assumptions, list of variables, calculations, and his conclusions are not published research and have not been submitted for peer review. In science, this is called conjecture. Conjecture in science is subject to refutation. So now we await refutation by other scientists.
All the above is simple, verifiable fact.
Here is a very partial list of basic questions you can expect to see in any refutation of Dr. F's conjecture that 5ppm is a reasonable test figure for e-liquid:
* is his recommendation intended to protect the theoretical "average" vaper, a "typical" vapor", the majority of vapers?...and which group
should it be designed to protect?
* is the assumption that e-liquid is consumed evenly over the course of 12 hours/day appropriate/prudent/reasonable?
* is his assumption regarding ml consumed per day appropriate?
* Is his assumption regarding level of flavoring appropriate?
* is his assumption regarding air-intake levels of vaping devices appropriate?
* is his assumption regarding lung capacity appropriate?
* is his assumption regarding the quantity of liquid vaporized in a given time period appropriate, given the range of equipment in popular use?
* is his assumption regarding hours/day spent vaping appropriate?
* etc.; each assumption must be fully-justified and in accordance & relation with the NIOSH standard he uses as a starting point
*** The big question: Is it appropriate/prudent/reasonable to take a NIOSH-recommended figure (5ppb) for an 8 hour/day, 5 day/week
weighted average exposure, and compute
total exposure, and allow it full exposure to that amount in an undefined, uncomputable period of time? That is in clear conflict with NIOSH's shorter-time limits and is not the type of calculation used in any exposure to any toxin in any regulation.
The burden of proof will be on Dr. Farsalinos. In the meantime, we have NIOSH's 5 ppb figure.