WordWeb Online

1. Of noxious stench from atmospheric pollution
   - mephitic
    
2. Filled with vapour
   "miasmic jungles";
   - miasmal, vaporous, vapourous [Brit, non-standard], vapoury [Brit, Cdn], vapory [US]

See also: cloudy, ill-smelling, malodorous, malodourous [Brit, Cdn, non-standard], minging [Brit, informal], pongy [Brit, informal], stinky [informal], unpleasant-smelling, whiffy [Brit, informal]