Gizmodo: Natural Gas Is Now More Deadly Than Coal in 19 States. Unhealthy air pollution generally brings to mind coal-fired plants spewing black soot from a smokestack. But that image may quickly be becoming outdated. A study published on Wednesday in Environmental Research Letters found that using natural gas and biomass in sources like buildings and industrial boilers actually caused more deaths in 19 states as a result of air pollution than burning coal.