Coal is made of up of a mixture of aromatic hydrocarbons like a anthracene, naphthalene. These are already toxic to humans. Add metals like mercury, antimony, etc.
Coal smoke is much worse than wood smoke.
Leading to, for example, acid rain.
Also just a guess, coal is a finer particulate matter than wood, I think that might give more particles off. Wood dust, nope, coal dust? Hell no. Also radioactive!
[] - https://www.scientificamerican.com/article/coal-ash-is-more-....
But yes, the article you linked talks about trace amounts of uranium and other materials that actually could be harmful.
This one is easy to research. I'm not trying to convince you of anything, just being helpful.
PM2.5 pollution, even at levels far lower than being seen now, is associated with literally hundreds of negative outcomes- lower IQ, worse test scores in standardized tests, more depression, worse ADHD, more asthma, more cancers (of both the lungs and other body parts), emphysema, as well as a whole host of issues related to full-body inflammation (ranging from auto-immune disorders to digestive problems).
The issues you're describing are studied after what I'd say is long term exposure. So far it's less than a week. A person with healthy lungs and no related problems will be back to normal if this ceases in a relatively short time. Of course, that doesn't mean we should relax about smoke season becoming a month-long annual event.
They say dosage makes the poison, but duration is important, too.