This standard BS 2742M:1960 Miniature smoke chart is classified in these ICS categories:
13.040.40 Stationary source emissions
91.060.40 Chimneys, shafts, ducts
A chart, printed in shades of grey matt lacquer, which when held at about 5 ft from the observer gives readings of the density values of smoke from chimneys. These are comparable with those obtained from the BS Ringelmann Chart (BS 2742C). The method of use is explained in BS 2742.