Is media blasted residue harmful? Options

[914itis]

My car was soda media blasted I think ( its the white stuff that looks like baking soda) before I got it and went on with the restore. There was powder everywhere. I cleaned all the visible residues before restoration and paint.

For the first time, I completed the installation of the heating system last month. As I had the heat on with the fan blowing, I noticed the soda smell coming out of the vents.

Can the smell do any harm?
What is the best way to clean the heat tunnel?

I don't think there is much in there, I uses a vac to blow and suck the dust before installation. Can I just detach the hose coming from the firewall / long to the flappers. Them disconnect the hose behind the speakers and water hose it ? What would you suggest?
All opinions welcome.

[Griffinroydonald]

Media always leaves residue when used as the media reduces to light powder as it cleans the parts being blasted. All forms of Media are rated as to how Agressive they are and this just means the hardness of the media being used. The light soda is the softest and does the least damage to surfaces and sand is the hardest. You must match the media to the material being removed. This is always looked apon as softer is better but takes longer and will leave a different finish. Air pressure also have different effects on the outcome of the finish.
I have used about everything you can think of to blast parts , cars , playground equipment and military vehicles. The key is to blow out the used media after use with large amounts of air several times. We have even flipped cars upside down to remove some forms of media. Find someone who has a large air compressure and an open unrestricted hose and blow out your system. Always wear a mask or even a hood when doing this as any media in the lungs is a bad thing. (IMG:style_emoticons/default/bye1.gif)