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Study: open trash burning worldwide significantly worsening air pollution; unaccounted for in emission inventories

Unregulated open trash burning around the globe is pumping far more pollution into the atmosphere than shown by official records. A new study led by the National Center for Atmospheric Research (NCAR) estimates that more than 40% of the world’s garbage is burned in such fires, emitting gases and particles that can substantially affect human health and climate change.

The new study provides the first rough estimates, on a country-by-country basis, of pollutants such as particulates, carbon monoxide, and mercury that are emitted by the fires. Such pollutants have been linked to serious medical issues. The researchers also estimated emissions of carbon dioxide, the most common greenhouse gas produced by human activity. Their paper is published in the ACS journal Environmental Science & Technology.

The contribution of open waste combustion to other pollutant emissions is rather substantial. When compared to the global emission inventories recently prepared for the Task Force on Hemispheric Transport of Air Pollution (HTAP, accessed 18 March 2014), the open waste combustion emissions of NMOC and carbon monoxide are each equivalent to 7 and 5% of the global total estimated anthropogenic emissions, respectively. The HTAP inventory does not include the emissions of open waste burning.

The global emissions of particulate matter (PM) from the open combustion of waste are very significant compared to the global anthropogenic emissions estimated for the HTAP inventory. The open waste combustion PM2.5 emissions are equivalent to 29% of the total global anthropogenic PM2.5 emissions, and the particulate organic carbon (OC) emissions estimated here are equivalent to 43% of the total global anthropogenic OC emissions. The mercury emissions estimated as part of this study are equivalent to 10% of the total emissions reported by the most recent assessment of the United Nations.

—Wiedinmyer et al.

Ratio of the emissions of PM10 (top) and CO (bottom) from open waste burning to total reported anthropogenic emissions from the EDGARv4.2 inventory. Credit: ACS, Wiedinmyer et al. Click to enlarge.

Unlike emissions from commercial incinerators, the emissions from burning trash in open fires often go unreported to environmental agencies and are left out of many national inventories of air pollution. For that reason, they are not incorporated into policy making.

Air pollution across much of the globe is significantly underestimated because no one is tracking open-fire burning of trash. The uncontrolled burning of trash is a major source of pollutants, and it’s one that should receive more attention.

—Christine Wiedinmyer, lead author

Quantifying the extent of burning trash may change how policy makers track emissions, as well as how scientists incorporate air pollution into computer models used to study the atmosphere.

Because trash burning is unregulated and unmonitored, Wiedinmyer said that actual emissions could be larger or smaller than the study’s estimates by a factor of two. Still, the analysis represents the most comprehensive effort to date to account for emissions from trash burning.

The new study was funded by the National Science Foundation, which is NCAR’s sponsor. It was co-authored by scientists from the University of Montana and the US Environmental Protection Agency who were also involved in measuring the composition of trash-burning emissions.

Trash burning is a global phenomenon, but it is most prevalent in developing countries where there are fewer trash disposal facilities, such as landfills and incinerators.

The amount of garbage burned in remote villages and crowded megacities is likely on the rise, as more people worldwide are consuming more goods. The trash often contains discarded plastics and electronics as well as traditional materials such as food scraps and wood.

To estimate emissions from trash fires, Wiedinmyer and her co-authors compared population figures and per capita waste production with official tallies of trash disposal for each country in the world. They estimated that 1.1 billion tons (1 billion metric tons), or 41%, of the total waste generated worldwide is disposed of through unregulated burning every year.

The countries that produce the most total waste, according to the study’s methods, are heavily populated countries with various levels of industrial development: China, the United States, India, Japan, Brazil, and Germany. But the study concluded that the nations with the greatest emissions from trash burning are populous developing countries: China, India, Brazil, Mexico, Pakistan, and Turkey.

By analyzing consumption patterns in each country, the research team then estimated the type and amount of pollutants from the fires.

The study concluded that as much as 29% of human-related global emissions of small particulates (less than 2.5 microns in diameter) come from the fires, as well as 10% of mercury and 40% of polycyclic aromatic hydrocarbons (PAHs). These pollutants have been linked to such significant health impacts as decreased lung function, neurological disorders, cancer, and heart attacks.

Trash burning in some countries accounts for particularly high quantities of certain types of pollutants. In China, for example, 22% of larger particles (those up to 10 microns in diameter) come from burning garbage.

The emissions of trace gases and particulate matter from open waste burning in countries with the highest overall emissions are significant. China has the largest emissions of any country in the EDGARv4.2 emissions inventory, which does not include emissions from open waste burning. The open waste burning emissions of CO, PM10 and NMOC calculated as part of this study are equivalent to 10%, 22%, and 9% of the total anthropogenic emissions for China.

—Wiedinmyer et al.

The global impact on greenhouse gas emissions appears to be less, though still significant, with burning trash producing an estimated 5% of human-related carbon dioxide emissions. (By comparison, the Kyoto Protocol strove for a global 5% cut in greenhouse-gas emissions from industrialized countries.) In certain developing countries—such as Lesotho, Burundi, Mali, Somalia, and Sri Lanka—the trash burning produces more carbon dioxide than is tallied in official inventories. This discrepancy can be important in international negotiations over reducing greenhouse gas emissions.

Wiedinmyer said the next step in her research will be to track the pollutants to determine where they are having the greatest impacts.


  • Christine Wiedinmyer, Robert J. Yokelson, and Brian K. Gullett (2014) “Global Emissions of Trace Gases, Particulate Matter, and Hazardous Air Pollutants from Open Burning of Domestic Waste” Environmental Science & Technology doi: 10.1021/es502250z



This is just one of the 1001 emissions currently not accounted for?

Many reported major emissions are often voluntarily underestimated.


We need to stop looking at garbage as just something to get rid of. It is a resource, and burning it is a waste of energy.


Correct ai_vin. How the new Calgary plant doing?


Wouldn't know, I don't live anywhere near Calgary.

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