Do chemical weapons harm the environment?

[TroyMorris]

According to Reddit, they do.  Personally, I've never noticed.  If they do, it's possible that I was managing my environmental harm for other reasons and didn't notice.  Forests, Tree Farms, Hybrid Forests, Centauri Preserves, and Centauri Preserves are not going free market.
 But it makes me want to write an AAR about minimizing environmental damage.

[Buster's Uncle]

Oh!  Please do.

[magic9mushroom]

According to Reddit, they do.  Personally, I've never noticed.  If they do, it's possible that I was managing my environmental harm for other reasons and didn't notice.  Forests, Tree Farms, Hybrid Forests, Centauri Preserves, and Centauri Preserves are not going free market.
 But it makes me want to write an AAR about minimizing environmental damage.

Gassing units outside a base is a Minor Atrocity and only gets you sanctions.

Gassing units in a base (slaughtering half the population) is a Moderate Atrocity (the others are Genetic Plague and Obliterate Base). These increase the length of sanctions, and if you do more than 20 of them then they start counting as Major Atrocities (all AIs declare war, clean mineral limit drops by 5 per Major Atrocity).

You have to be pretty indiscriminate with nerve gas use in order to start racking up ecodamage, but if you spam it against bases you will start getting mass ecodamage. In multiplayer, this is actually quite notorious, because it's the easiest way for the Pirates to deliberately cause mass ecodamage (in order to produce global warming and plunge the globe underwater).

Repealing the UN Charter avoids the CML drop along with the other effects, though.