Re: What are the byproducts of burning styrofoam. Are they dangerous?

Rob,

Put simply, yes!.

To quote from one MSDS(Material Safety Data Sheet),

"In smoldering or flaming conditions, carbon monoxide, carbon dioxide, 
carbon are generated. Evolution of small amounts of hydrogen bromide, 
hydrogen chloride and hydrogen fluoride occurs when burned or heated over 
250C (482F); under high heat, non-flaming conditions, small amounts of 
aromatic hydrocarbons such as styrene and ethylbenzene are generated. "

If you want to know the effects of the individual proucts, then search the 
WEB using +MSDS in the search term along with the chemical name.

Thick black smoke is produced (it is the "carbon" referred to above) and 
signals the whereabouts of the danger.  In the event of encountering a 
fire, always move at 90 degrees to the wind direction to escape the smoke 
and fumes, and call 911 !!

Keep safe.