Fluorescents bulbs are good energy efficient alternatives to incandescents, but they do require mercury in their manufacture, and this can be a problem if they are not disposed of properly. In response to this, Philips introduced a range of low-mercury fluorescents: ALTO bulbs.
Philips claims the bulbs have the lowest amount of mercury of any bulb on the market at less than 3.8 mg per bulb, or about 70% less mercury than other bulbs. To achieve this, Philips uses a specially developed mercury capsule which ensures the exact amount of mercury is placed in a tiny glass capsule which is attached to the lamp cathode.
Philips claims that the bulbs last about twice as long as other fluorescents.
Low-Mercury Fluorescents Bulbs: ALTO by Philips (TreeHugger)