This part of ISO 5660 specifies a small-scale method for assessing the dynamic smoke production rate of essentially flat specimens exposed to controlled levels of radiant heating under well-ventilated conditions with or without an external igniter. The rate of smoke production is calculated from measurement of the attenuation of a laser light beam by the combustion product stream. Smoke obscuration is recorded for the entire test, regardless of whether the specimen is flaming or not. The measurement system prescribed by this part of ISO 5660 is an extension of the apparatus described in ISO 5660-1. Therefore, this part of ISO 5660 is used in conjunction with ISO 5660-1.