Some background info first. The body has two main mechanisms of self-protection: the skin, acting as a physical barrier, and the immune system that comes to the rescue once an "intruder" has managed to get past this barrier (through a cut, mucous membranes or the respiratory system). The immune system does not really differentiate between different types of "intruders", be it viruses, bacteria or non-organic substances, and as a result responds in pretty much the same fashion to all of them. First it releases chemicals (hormones and other factors) at the site of the breach, then it calls in the cavalry (white cells and other intruder-murdering squads), then finally it _may_ give the signal to put the rest of the body on high alert to make it more difficult for further intruders to get through via other routes.
The immune system has very good memory. Pretty much every single substance it comes into contact with since birth gets classified and remembered as good, bad and... really bad.
The really bad guys are considered to be potentially lethal and as a result the
the immune system puts the whole body immediately on high alert every time it
encounters them as to get rid of them as quickly as possible. It usually takes
multiple exposures and a rather "trigger-happy" immune system (i.e. a degree of
genetic predisposition) to develop this sort of hypersensitivity to a substance.
But once it's established then the response can be overwhelming as these quick
response mechanisms are rather non-specific and often completely out of
proportion to the actual damage that the substance (antigen in the medical
lingo) can do. To go back to your particular case. You've been working with this wood (that I admit being unfamiliar with but which is obviously chemically capable to trigger an immune response) for a prolonged period of time. Your immune system responded mildly to it initially (you didn't notice any difference) but gradually got to classify it as potentially dangerous. After this has happened further exposure triggered a full-blown "code-red" response which you recognised as rash and swelling. Though this can be dramatic enough it's not the end of the story.
If you continue to come into contact with this known antigen, especially without taking a few weeks' break (which can sometimes help the immune system partially "forget" about it) this response will get quicker and more pronounced every time it occurs. From being just the skin that swells up your airway can start swelling up as well causing breathlessness and wheezing. In dramatic situations the swelling can be so bad that your airway gets completely obstructed... and you're dead!
I've seen it happen a few times in my career and it's not funny. My advice would be to stop using this wood immediately, get someone (not you!) to blow-clean your workshop (wearing a respirator!), air it for a few days and take a holiday from woodworking for a week or two! I am not aware of any protective measures (besides a space-suit
)
that can effectively prevent contact with the wood-dust as even a minute amount
can trigger a reaction if you're so inclined. Also bear in mind that as someone already mentioned, becoming sensitised to one type of wood can potentially make you intolerant to other types as well (due to chemical similarity). So just switching to something else without taking a break can contribute to making you intolerant to that wood type as well (cross-sensitisation). If you are a professional woodworker this can be catastrophic for your career so beware.
Finally, let your doctor know. They may have more specific information available and knowing you medical history they can give you valid advice or even refer you to a specialist if required.
George