The fumes alone would reach a nuclear level. The heat in all chiles, whether hot or mild, is due to the flavorless, odorless, colorless chemical known as capsaicin. In 1912, William Scoville, a Detroit pharmacologist, measured capsaicin by having a panel of hardy souls sip a sweetened solution of dried chile peppers dissolved in alcohol. The concoction had decreasing amounts of capsaicin until it no longer burned. In recent years, this subjective test was converted to a chemical process, but with results still expressed as Scoville units.
Disagreement is common, but the ratings give a good idea of relative chile heat.
This year's cold, wet spring has postponed the fresh chile season all the way from California to New Mexico. Farmers' markets throughout the Bay Area are often a good bet, as are specialty produce shops, ethnic groceries and many supermarkets. This market supplies restaurants, so there's usually a good variety of serranos, poblanos, Anaheims and habaneros. It has poblanos, jalapenos, serranos, Anaheims and a large variety of dried chiles. One of the biggest supermarket selections of chiles from Anaheims and jalapenos to fiery habaneros.