Hi David,
Unfortunately, I doubt that natural plasters, including lime, could do much to absorb VOCs. Our main concern with MDF is formaldehyde. It's in the resin that holds the
wood fibers together and outgasses for quite some time after the product is installed. My guess is that the best bet in such situations is time...time for the formaldehyde to evaporate (outgas). Unfortunately, people living in the trailers are being exposed this entire period.
Dan