Dry Ice Blasting for Mold

I am a firm believer in applying new technology to old problems. Thats why I was the first in Northern California to get into dry ice blasting for mold. I think that there are projects where nothing else will do the job... and I think there are projects where dry ice can cause more harm than good. If your going to use this technique, you have to understand that it will create a huge amount of dust (with the mold mixed in). The cleaning phase of your project will almost certainly take you twice as long. Another limitation is the air quality within the containment. I recently did a mold clearance on a crawlspace where the contractor used dry ice blasting to remove the mold from the joists and subfloor. I asked one of the workers what kind of respirators they used for this and he showed me a P-100 half face respirator... are you kidding me?  Dry ice is the solid form of CO2. At -130 degrees F, it instantly changes into the gas phase when it hits a surface that is significantly warmer (there is no liquid phase like normal H2O ice). The volume of the gas is 80 times greater than the solid phase, so you get a tiny thermal explosion on the surface which does a very good job at removing mold from wood. The problem is that you must either replace the CO2 with fresh air, or wear a supplied air respirator where the fresh air is pumped into the face mask from a pump that is located away from the work area. A crawlspace is a very confined space, so when the oxygen is displaced by this huge amount of CO2 it can be deadly for the workers. The contractor is very lucky no one was hurt, but the look he gave me when we discussed this tells me that he will do it again. Another project I did in Fremont... again a crawlspace... the contractor did not place the living areas under positive pressure, so the result was plumes of wood dust coming into the house from around each of the heat registers. There was a thick layer of wood/mold dust on every surface of the home. I believe that the clean-up of the home cost the contractor more than the value of the original job. The latest dry ice mold project was in Marin City... the framing and subfloor looked great but we just couldnt get it to pass. On this job, the contractor just didnt realize how much dust was produced and he thought he could just clean the structure like a normal mold job. We have not cleared this one yet but I think the contractor now has a new understanding of what is involved in dry ice blasting mold.