• Waste management in Japan
• Circular economy in Japan
• Waste management in Asia
• Disaster waste management

Black or gray smoke rises from burning of plants or plastics. These colors are actually those of smoke dust including particulate matters produced by the burning. Smoke dust refers to the so-called "soot," or "soot dust" to be more accurate. There are concerns about potentially carcinogenic substances in soot dust itself and fine (2.5 μm or less) particulate matters (PM2.5) which could possibly penetrate deep into the lungs and damage the respiratory system. Furthermore, the burning of materials containing nitrogen and sulfur may cause harmful acid rain by producing nitrogen oxides and sulfur oxides, whereas the burning of those containing heavy metals and chlorine may cause air pollution by producing toxic metals and dioxins¹⁾.

In Japan, open burning of waste is banned as a matter of principle under the Waste Management and Public Cleansing Law, because there are concerns about (1) an increase in the number of patients with respiratory disease and deteriorated visibility by soot, dust, and other related products of open burning of waste, (2) generation, emission and pollution of dioxins and other hazardous chemical substances, and (3) the risk of fire-spreading. In developing regions of Asia and Africa, however, some people collect waste electrical cables, burn them in the open air, recover the copper wire from the ashes, and sell it for a living. During an on-site survey which our research group conducted at an E-waste recycling site in northern Vietnam, we saw people burning waste electrical cables. The workers' skin and clothes were covered with black soot dust. According to the results from a set of laboratory simulations of open burning practices using printed circuit boards and insulated wire²⁾, various hazardous substances were found in the air emissions and residual ash samples. These substances included, but were not limited to, harmful metals such as lead of solder and copper of a copper wire, brominated flame retardants (BFRs) used to make the fire-resistant plastics (see the December 4, 2006 issue: Flame Retardants [in Japanese]), and chlorinated and brominated dioxins formed unintentionally from chlorine in polyvinylchloride (PVC) resin used to cover the cable and bromine in BFRs. The workers at the recycling yard had their mouths covered by a towel or a mask. However, since it was a very primitive protection method, they may have been inhaling toxic smoke containing harmful metals, BFRs, and dioxins almost every day. Appropriate immediate countermeasures to prevent health damage under such condition would include avoiding the toxic smoke inhalation by always working on the windward side and wearing an authentic dust protective mask. Thorough gargling and hand-washing with soap after work or after getting close to the open burning yard would be also effective for improving these workers' safety. Meanwhile, encouraging people to stop the open waste burning itself is becoming increasingly important in developing regions of Asia and Africa.