The term atmospheric brown cloud is used for a more generic context not specific to the Asian region.
The Asian brown cloud is created by a range of airborne particles and pollutants from combustion (e.g., woodfires, cars, and factories), biomass burning (This is important see below this paragraph!) and industrial processes with incomplete burning. The cloud is associated with the winter monsoon (November/December to April) during which there is no rain to wash pollutants from the air
Biomass is an industry term for getting energy by burning wood, and other organic matter. (Dried snimsl dung in 3rd world countries, see below.) Burning biomass releases carbon emissions, around a quarter higher than burning coal, but has been classed as a "renewable" energy source in the EU and UN legal frameworks, because plants can be regrown. It has become popular among coal power stations, which switch from coal to biomass to comply with the law. Biomass most often refers to plants or plant-based materials that are not used for food or feed, and are specifically called lignocellulosic biomass. As an energy source, biomass can either be used directly via combustion to produce heat, or indirectly after converting it to various forms of biofuel. Conversion of biomass to biofuel can be achieved by different methods which are broadly classified into: thermal, chemical, and biochemical methods.
Professor Durga D. Poudel, University of Louisiana at Lafayette, Louisiana, USA
In December of 2018, I visited Kathmandu with the main purpose of understanding and preparing logistics such as hotels, transportation, etc., for our Study Abroad Pilot program that my university, the University of Louisiana at Lafayette (UL Lafayette), USA, was considering to launch during the summer of 2019 in Nepal. UL Lafayette has been running its Study Abroad Program in Costa Rica, England, France, and Italy. As usual, the city of Kathmandu was under the havoc of the worst air pollution (The picture presented here, however, was taken in May, 2019).
Dry animal dung fuel (or dry manure fuel) is animal feces that has been dried in order to be used as a fuel source. It is used as a fuel in many countries around the world. Using dry manure as a fuel source is an example of reuse of excreta. A disadvantage of using this kind of fuel is increased air pollution.
- In Egypt dry animal dung (from cows buffaloes) is mixed with straw or crop residues to make dry fuel called "Gella" or "Jilla" dung cakes in modern times and ""khoroshtof"" in medieval times. Ancient Egyptians used the dry animal dung as a source of fuel. Dung cakes and building crop residues were the source of 76.4% of gross energy consumed in Egypt's rural areas during the 1980s. Temperatures of dung-fueled fires in an experiment on Egyptian village-made dung cake fuel produced
""a maximum of 640 degrees C in 12 minutes, falling to 240 degrees C after 25 minutes and 100 degrees C after 46 minutes. These temperatures were obtained without refueling and without bellows etc.""
Also, camel dung is used as fuel in Egypt.