Toxin bunker

Prior to the GLA conflict, dangerous chemical and biological weapons like anthrax were stored in specially designed concrete bunkers, which could store large amounts of dangerous chemicals safely for prolonged periods of time. When GLA rose to power, they became high priority targets for them, as the volatile and dangerous contents of the bunkers were an ideal addition to their arsenal, as they'd replace their amateur weapons with military grade biochem weapons.

When damaged, the bunkers could leak their contents, leading to an extremely hazardous contamination of the surrounding area.