Firstly thank you very much for your useful reply. It is interesting and it is hard for me to find answers, that's why I came to this forum, I am just expanding my knowledge.
I think BHT is a safe additive from what I understand and only present in small quantities, but I will read up on it again.
I have also read that the PEL and STEL are rather strict, I mean I have read various accounts of groups of people being exposed up to 10ppm for a period of half hour or so, without harmful effect. What true amount is harmful for short term exposure is probably far higher. From what I have read 30ppm and above inhaled for several minutes (or more) is more than likely to be getting into the "serious risk area" in terms of damage to the lungs, but the oral LD50 for an adults is like several thousand times higher when ingested (I read around 10-15ml). Seems to be directly damaging to the lung tissue in high concentrations (>30ppm) or longer term exposure. I am not convinced about it being too carcinogenic, unless the exposure is continual and longer term.
In regards to my asthma, it is under good control. I have powerful medications to control it. It is something I will have to look out for. If I start wheezing in proximity to the stuff then that will give me a clue
I am going to have to make sure I get better quality next order. I rushed the order when I did it and I missed some of the higher purity stuff they have for sale. Well I am learning to read the labels with greater care now.
Sorry I edited this post a few times to try and get it right.
I'll finish by saying that I am very interested in any knowledge anyone has of Diethyl Ether and issues relating to its chemical purity. Diethyl Ether- provided it is stabilized, is not something that especially concerns me in regards to handling or storage- I mean I feel I understand its nature enough to provide a controlled environment for it, I have great respect for this stuff. I have a great interest in the stuff for a multitude or reasons, it is a tool with many uses. It is also historically fascinating.