You'd have to be a real gas pump aficionado to notice the new gear that gas stations across California are required to have installed by April 1st. California's gas nozzles have been outfitted for some time with vapor-capture devices, designed to cut back on the amount of volatile organic compounds – those smelly fumes - that escape when you pump gas. This explains that accordion-style rubber sheath that bunches up against your gas tank when you pump – a feature you don't necessarily find in states with less stringent air quality laws.
When those fumes combine with sunlight, along with other emissions, they form ground-level ozone, an air pollutant which acts as a greenhouse gas, contributing to global warming much like carbon dioxide does.
Take a look at this nifty, infra-red video footage from the California Air Resources Board, showing how fumes disperse from the gas pump when they aren't properly collected.
[jwplayer config="QUEST Video Player Small" mediaid="38489"]
Ground-level ozone is also a real problem for human health, especially for people with asthma and respiratory disease. Just this week, UC Berkeley released a study finding that people living in areas with high ozone levels, like Los Angeles and the Central Valley, have a 25-30% greater risk of dying from respiratory disease than those in less ozone-heavy parts of the state, like San Francisco.