Air is frequently contaminated.
air pollution, when an individual breathe in too much contaminated air it may lead to Asthma
it can get contaminated by passing thought traits that are already contaminated
I think it depends how badly they were contaminated, but if you let them air for a day or two they should be fine.
Refrigerant contaminated with air won't function properly.
The homeowners had their water tested for contaminants before drinking from the faucet.
The environment (soils, air, waters) was contaminated.
If it is left open on the bench it can be contaminated by bacteria in tyhe air, e.g. micrococci. If the loop was not flamed adequately before innoculation this can also cause contamination. and also if the medium used was not sterile in the first place the plate will be contaminated.
primary pollution