Not fit or suitable to be breathed: unbreathable exhaust fumes. (adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "unbreathable" in a sentence
"Far beyond human stench and waste to unbreathable."
"These are the same folks who oohed and ahhed over the multi-billion dollar Beijing Olympics venues while ignoring the air that was unbreathable."
"After all the fish have been killed; after all the trees have been cut down; after all the soil has eroded away; after the air becomes unbreathable; when we humans are forced to eat our money; then will we understand?"