Supportive care is the mainstay of treatment (no specific antidote exists)
Use supplemental oxygen only as needed, and then at low concentrations to avoid reactive oxygen species formation
If intubation required, use ARDS lung-protective strategies
Note: Evidence is lacking, and generally based on case reports and expert opinion - consultation with local poison control is recommended
Corticosteroids
N-acetylcysteine (IV or nebulized)
NSAIDS (e.g. Ibuprofen, Colchicine)
Terbutaline
Nebulized albuterol
Phosgene
Blister chemical agents 
Levoleucovorin
Lewisite 
Tdap
Sulfur mustard 
PALS 
Phosgene oxime 