Diode-lasers have experienced limited success as environmental monitors because polluting chemicals weakly absorb light at commercially available diode-laser wavelengths. Also, although diode lasers offer one of the fastest and most sensitive ways to detect toxic gases, federal agencies and consumers often view optical remote sensing as an ''advanced technology,² requiring specialized training. Several forces could change this situation. New technologies that exploit extended cavity designs and nonlinear materials mean that a single device can detect multiple chemicals. Automation and new diode lasers have reduced the need for specialize technical know-how. Meanwhile, strained semiconductor materials and quantum cascade diode laser architectures are pushing into the mid-IR a crucial portion of the spectrum for toxic pollutants.