The combination of tunable narrowband laser sources with the highly sensiti
ve photoacoustic (PA) detection scheme bears great potential for pollution
monitoring. The PA technique compares favorably with other optical methods
such as multipass transmission or cavity ringdown spectroscopy. In trace ga
s sensing, the main requirements are high sensitivity and selectivity, mult
icomponent capability and large dynamic range. PA spectroscopy can generall
y offer these features. As example the detection of ppb to sub-ppb gas conc
entrations even in multicomponent mixtures and isotopic selectivity have be
en demonstrated. This report discusses some main characteristics and recent
results illustrated by some examples.