If you happen to have a mod that allows you to return to the Sierra Madre after completing its quest (such as viennacalling's Cross-DLC Transportalponder, found here), you may have noticed that the Hazmat Suit from Old World Blues barely helps with the Cloud at all. Sure, the fact that there are Ghost People wandering around in the outfit implies that it's not entirely effective, but you just drop dead from a couple minutes of exposure.

With this mod, wearing the full Hazmat Suit grants total immunity to the damaging effects of the Cloud. You will notice, however, that your vision still blurs, and N.E. makes no guarantees that the air inside the suit will be spring fresh. If you limit your exposure to under one month at a time, you should be fine. Probably.

This mod works by making the Cloud script check if the player is wearing the Hazmat Suit and Hazmat Darklight Cowl before dealing damage. It does not edit the suit and cowl directly, and therefore should be compatible with all mods that change its properties.