Unregulated 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 estimates that more than 40 percent 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.

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.