Combined optical procedures. There are actually different proprietary optical smoke measurement units like the 'nephelometer' or even the 'aethalometer' which use numerous distinct optical approaches, together with multiple wavelength of light, within just one instrument and apply an algorithm to offer a fantastic estimate of smoke. 1600 – Tobacco https://nuso35555.scrappingwiki.com/1359356/the_2_minute_rule_for_cigarettes