Does anyone have any ideas on how to protray enviromental dangers like radioactive, toxic or just hostile environs (( extremely cold, extremely hot or low oxygen)). What way do you think would be the most fair way to have these dangers. I am especially interested in warfare, I would loved to be able to simply shell my group give them a reall taste of the facelessness of long range war!

@Toxic/Polluted Environment
Daily (or hourly!) checks on Toughness, with bonus (or "auto success") for equipment "shielding" them against the hazard. If a test isn´t passed, make them lose Toughness (1d5 oder 1d10; and another one point or dice(!) per level of failure).

The toughness loss might temporal, but they will only recover (one point per hour) as they left the area. In case of gases, it might either permanent or a portion of it (say: one out of five or one out of 10) might be permanent. The recovery might be even slower (one point per day) if some of the loss is indeed permanent. The "permant loss" could be reduced by proper medical treatment.

@Shelling
Either, simply give them damage or (if they are shelled during a long march) ask them for agility/dodge tests (as they dive for cover). If they miss them, they get damage (and even more damage per level of failure). A hearing base perception test should be made ahead to hear the "whistle" of ordanance in the air. The more success, the easier will be the role needed to dive for cover

Gregorius21778 said:

This is about the same approach I took when a party was stuck on a planet with arctic conditions. As long as they had proper ( functioning ) cold weather gear, they got a hefty bonus for Toughness tests to resist the cold. Failing a test resulted in Fatigue and failing with 2+ DoS in frost bite ( D5 Wound loss ) in addition. The check were made every couple of hours in "normal" conditions and more frequently in "extreme" ( storm etc. ) conditions. With varying degrees of difficulty.

The party got understandably worried when their warm coats gor shredded in a fight with an Ork patrol. Injuries don´t heal well in cold conditions ( penalty for Medicae checks ) and they were far away from the nearest human settlement. They managed ( barely ) to reach civilization without casualties. They got a whole new level of appreciation for Navigation (Ground ), Survival and Tracking skills .