[Emissions from combustion of indoor dust (author's transl)].

Combustion of dust is an old problem which has gained a new importance since the introduction of electric storage heaters for space heating. Physico-chemical changes caused by heating indoor dust in a model apparatus were investigated. Four dust samples of different origins were heated at three temperatures (200, 400, 600 degrees C) for three residence times (5, 15, 30 min). The higher the temperature, the higher the weight loss expressed as percentage (15 to 75%). The residence time had no effect on the loss. Three dust samples showed pH of about 7 before heated, while the fourth showed pH of about 10. After heating to 200 degrees C, the pH of one of the samples rose from 7 to 10. When heated to 400 and 600 degrees C, all the samples showed pH values between 10 and 11. The residence time had no effect. The pH of the gaseous reaction products did not show uniform pattern at 200 degrees C. At 400 degrees C, the measured pH was between 7.5 and 8.5, while at 600 degrees C no further change was observed. Changes in pH took place during the first fifteen minutes. Chemical analysis of the reaction products with help of detector tubes indicated that dust samples when heated emit carbon monoxide, carbon dioxide, oxides of nitrogen and ammonia.