Arctic temperatures may be sweeping across the United States this week, but you might want to think twice before turning up the heat.

According to a new study from Boston University, air pollution generated by home heating systems like oil, gas, and wood burning kills 10,000 Americans per year.

The pollution comes from residential combustion sources (RC) that are used to heat pipes and radiators inside homes. When oil and gas are burned, microscopic particulate matter smaller than 2.5micrometers (PM2.5) can get into the lungs, organs, and bloodstream, which can be fatal for those battling lung or heart disease as well as the elderly and children.

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The pollution from home heating is worse in cities than in less densely populated areas because more people are heating more homes, according to the study. So the coasts of the US, which are more heavily-populated than the center of the country, have the highest concentration of PM2.5.

Coal is also a major contributor to PM2.5 pollution, and is responsible for killing twice the number of Americans per year (20,000) as the other three categories of RCs.

The World Health Organization recently concluded that pollution is responsible for the deaths of 1.7 million children around the world, or one in four deaths for children under the age of 5. Then there are the many millions of other children who are irreparably damaged from, but not killed by, pollution.

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As Fast Company noted, about 20% of urban pollution is caused by burning fuel to heat homes, and it’s the second-largest contributor to urban pollution after traffic. So if you’re already walking, biking, or carpooling more to cut down on traffic pollution, it’s time to start thinking of creative solutions inside the home to cut down on heating pollution.

FastCo recommends wearing extra layers instead of turning up the thermostat, but better-designed housing that maximizes energy efficiency and better retains heat can also help.