The disposal of waste in industrialized countries usually takes place in controlled landfills and incinerators, whereas in many poorer countries, garbage is simply thrown on heaps and burned in the open air. How many such unregulated garbage fires exist, and what consequences they have for the environment, was largely unknown.

Christine Wiedinmyer, National Center for Atmospheric Research (NCAR), Boulder, Colorado, USA, and colleagues have performed the first comprehensive and consistent estimates of the global emissions of greenhouse gases, particulate matter (PM), reactive trace gases, and toxic compounds from open waste burning. They collected data from every country on population, waste production, and available statistics on waste disposal.

41% of the entire amount of waste accumulated worldwide is disposed by unregulated open burning. The greatest amounts of emissions are produced by China, India, Brazil, Mexico, Pakistan, and Turkey.

As much as 29 % of particulates, 10 % of mercury, and 40 % of gases known as polycyclic aromatic hydrocarbons (PAHs) comes from trash burning fires. 22% of China’s total reported anthropogenic PM₁₀ emissions come from open domestic waste burning. However, global emissions of CO₂ from open waste burning are relatively small compared to total anthropogenic CO₂.

According to the researchers emissions of many air pollutants are significantly underestimated in current inventories because open waste burning is not included.

• Global Emissions of Trace Gases, Particulate Matter, and Hazardous Air Pollutants from Open Burning of Domestic Waste,
  Christine Wiedinmyer, Robert J. Yokelson, Brian K. Gullett,
  Environ. Sci. Technol. 2014, 48 (16), 9523–9530.
  DOI: 10.1021/es502250z