HEPA filters capture almost all particles in the air that are zero point three microns in size or larger.

VOA: special.2009.07.14

dT/dp is mu JT. So for a real gas like air, this is a positive number. It's not zero.

所以对于像空气这样的真实气体，这是一个正数，不等于零。

麻省理工公开课 - 热力学与动力学课程节选

They form when the air temperature is about fifteen degrees below zero Celsius.

VOA: special.2010.01.05

"As a public company, stock is our currency, " explains the company's chief, Steven Schneider, who took the top job when Zap, which stands for "zero air pollution, " bought Schneider's auto repossession business in 2002.

FORBES: Shock Jocks

You have to understand, after spending 12-15 hours at ground zero, the air in this area is very heavy, it's almost suffocating.

CNN: Steelman and Angeli: Search and rescue at ground zero

For years they were caught up in disputes over whether the air at ground zero was really toxic -- the Environmental Protection Agency long claimed it was safe -- and whether the illnesses could be linked to the attack site.

CNN: 9/11 responders wait for compensation for their illnesses