Many woods contain viruses, and desert ironwood has natural pesticides that are powerful enough to put Ortho to shame. It can cause fungal infections in the lungs leading to pneumonia, and even death.
I have first hand experience with Ironwood, thinking, it's only wood(like allan above), and grinding one side down to see the grain, and that night I had trouble breathing.
For the next three weeks I lay in bed with my heart pounding so hard I thought each beat would be the last, and barely able to breathe.
The local hospital said if I didn't have cash, or insurance, they prefer I not come in.
Yes I know it's not legal, but when has that ever stopped the medical profession.
When I finally started to recover, I read an article in one of the cutlery mags I had coincidentally, just received, about toxic woods, and ironwood was right at the top, with the very symptoms I had, except I was able to skip the more lethal end.
It's no joke to get stuff like this, and someone with a weak heart could easily die from the symptoms, and it would just be written off to heart failure, as no doctor would think to check for something like a virus, or allergic reaction to wood.
In the area where I live, starting in November, the people would start lining up at the various doctors offices(my wife among them) with chronic inflammations of the lungs leading to infections, bronchitis etc. This went on every year.
They would take a steady diet of antibiotics till the weather warmed up in May.
I was talking to one doctor who is a friend of mine about this, because I suffered from headaches so bad as to be crippling from Novenber through May, I had suspected it had a lot to do with the wood stove but wasn't sure, the doctor asked if we burned juniper, and or cedar. The answer was yes as that was the only wood the forestry people would allow to be cut for firewood here and everybody in this valley burned it.
The doctor said that about 75% of people exposed to juniper will become allergic to some degree, usually resulting in lung inflammatins etc.
He also said he refused to treat people who continued to use woodstoves, or fireplaces. He said once you became sensitized by stuff like juniper, or cedar, you'd most likely be sensitive to other woods also.
People used these stoves because we didn't have natural gas in many areas, and the electric company sold power to us at 15.5cents a KWH(and it cost a fortune to heat with electricity), though they sold electricity to california who resold it to their customers for 3.5 cents a KWH, hence the woodburning here.
We finally got gas piped in, I quit using the juniper(and the wood stove altogether), and my wife hasn't been sick once since with any chest problems(my headaches diminished greatly), as has been the case with all I know in this area, including my neighbors, one of who spent about $5000 on tests to figure her breathing problems out, and the dizzy spells etc., and she was the head operating room nurse at the hospital here.
She finally ran into one smart doctor who asked her about burning juniper. She stopped, and so did her symptoms.
People around here have mostly stopped using wood stoves, and fireplaces, and the general health has greatly improved.
But you have to wonder how this will affect older people here in the long term.
Sorry for the overly long post, but I figured these things relevant.
A lot of my symptoms were similar to that. 
