Smoke Opacity Relative to Player Health

I have a particle system emitting smoke. I am attempting to make the apparent thickness or darkness of the smoke relative to the health of the player. To do this, I am applying the relative vehicle damage (0 to 100) to the alpha of the particle system start color. Even when I divide the player damage by some number (6 is what the snipped below uses), the darkness of the smoke sees way beyond what I expect. For example, an alpha of 30 looks as dark as 255. Any thoughts? Better way to do this?

         var smokeColor = smokeParticles.startColor;
         float smokeAlpha = (255/100) * (vehicleDamage/6);
         if (smokeAlpha > 255)
         {
             smokeAlpha = 255;
         }
         print("smoke alpha " + smokeAlpha.ToString());
         var newcolor = new Color(smokeColor.r, smokeColor.g, smokeColor.b, smokeAlpha);
         smokeParticles.startColor = newcolor;