Black Carbon in Ambient Air and Climate Change Implication: Long Term Data In Six Asian Countries

Abstract:

Black carbon (BC) is the light absorbing component of atmospheric aerosols and could contribute significantly to atmospheric radiation balance that may lead to global warming. BC is the product of incomplete combustion and is originated from various combustion processes. These fine soot particles are even more toxic with the absorbed semi-VOC including the carcinogenic PAHs on the surface. Rapid increase in the source intensity such as urban traffic, different types and scales of industries, and open agriculture burning in Asian developing countries may lead to high build-up of BC particles in the atmosphere. Reduction of ambient BC levels would benefit both air quality and climate. This research collects the ambient PM data from 6 countries (Thailand, China, India, Indonesia, Philippines, and Vietnam) within the framework of the regional air pollution project AIRPET since 2001. The black carbon content of in fine (PM2.5) and coarse (PM10-2.5) show a clear seasonal trend and also varies significantly between the urban and remote sites in each country. The highest BC content in PM2.5 was observed in dry season, reaching above 20 µg/m3 in Beijing and Manila. Significant lower BC was observed in urban areas during wet season, mostly below 10 µg/m3. BC levels in the remote sites are significantly lower than the BC in urban areas indicating significant contribution from local sources. The impacts of ambient BC on climate forcing are investigated in comparison with carbon dioxide.