You can carry out a test ,
1- take a sample of the air in a test tube
2-add limewater to the test tube
3- result : if it turns milky/cloudy it has microorganisms
4- reason: because every microorganism respires , and so it produces Carbon dioxide .
and limewater is the test to show the presence of Carbon dioxide .
Anaphase
explanation
searching it up would’ve been easier smh
