Here on Mauna Loa, air is collected on a 40 meter (130 foot) tower (left) and analyzed for CO2 content. At right, a powerful laser beam is used to measure aerosols and particles in the air up to 45 km into the stratosphere.
Similar to the global trend, warmer Southern States have more venomous species than North States. Arizona is the clear winner (or loser) with over 30 species.
In fact more people die from wasp and bee stings than from snake bites. http://www.idahogeocachers.org/images/graphics/rattler.jpg (broken link) The only poisonous snake found in Idaho is the Rattlesnake. Rattlesnakes bite their victims with fangs that are hinged to swing downward from the snake's upper jaw. Venom is injected into the victim through grooves along the fangs.