Common pollutants in air are oxides of nitrogen emitted by car exhausts, which are toxic and can cause acid rain and other damage to the environment, as well as risks to health. In a NOx analyser, a sample of exhaust gas is mixed with ozone, producing a chemiluminescent reaction.
The light emitted is measured by a photomultiplier and the concentration of the NOx gases is determined. This application requires a red-sensitive photomultiplier.
SOx gases can also be detected with this technique. Very low concentrations can be detected, down to the ppb level. The most sensitive systems require the use of cooled photomultiplier detectors which can be supplied to special order.
The presence of harmful bacteria in water can be detected with rapid microbiology techniques, using luminometers.