The Air Force's new anti-fire foam is much less toxic

It wasn't that the old foam was ineffective — far from it. The problem was that the foam came with some serious drawbacks. Most notably, the old foam was quote toxic, both to personnel and to the environment. The old version of AFFF made use of two chemicals, known as PFOS and PFOA. Both of these were unsafe for consumption in even the tiniest amounts (measured in parts per trillion).