Pollution from natural gas is now responsible for more deaths and greater health costs than coal in Illinois, according to a new study highlighting another hazard of burning fossil fuels that are scrambling the planetâs climate. Researchers at Harvard University found that a shift away from coal during the past decade saved thousands of lives and dramatically reduced health impacts from breathing particulate matter, commonly known as soot. But the numbers declined only slightly for gas, another fossil fuel that by 2017 accounted for the greatest health risks. About half the deaths from soot exposure that year can be attributed to the stateâs reliance on gas to heat homes and businesses, the study found. Coal is more deadly only when used to generate electricity.