You may recall that gasoline is a Volatile Organic Compound. Gasoline vapors can combine with nitrogen oxides to cause ozone.

Gasoline vapor escapes from our vehicles when the vehicle sits in the hot sun and the gasoline in the tank escapes the tank and when gasoline or gasoline vapors leak from the fuel lines routing the fuel from the tank to the engine. Gasoline vapor is spewed out the tailpipe an into the air when a cold engine starts and isn't yet up to proper operating temperature. Gasoline that isn't burned during the combustion process in a poorly tuned engine will also escape into the air.

But even before all these wasteful steps can occur, gasoline can escape from the tanker truck delivering gasoline to the gas station, and when you're pumping gasoline into your car's tank.

Stage I vapor recovery aims to capture the fumes from the tanker-to-gasoline station pumping process and put them back into the tanker itself. Stage II vapor recovery is intended to keep fumes from leaving your car's gas tank as you fill up, sending the fumes instead back to the underground storage tank in the gas station.

When an area goes into nonattainment, many of the region's gasoline stations must be equipped with Stage I and Stage II Vapor Recovery systems. For more information, visit