Bad air

According to the Global Burden of Disease Study, air pollution causes more deaths than malnutrition, obesity, alcohol and drug abuse, and unsafe sex. Cardiovascular and pulmonary diseases, as wells as respiratory infections, account for the majority of deaths from air pollution. Furthermore, half of the air pollution mortality is statistically attributed to outdoor air pollution, researchers said, while the other half is attributed to indoor air pollution that generally comes from burning coal or wood for heating or cooking. If power plants were changed over from coal to natural gas this would eliminate sulfites, sulfates, nitrites and nitrates all of which cause acid rain. It would also eliminate heavy metals like mercury, lead and arsenic and the huge piles of coal ash that are accumulating. The ash contains many other poisons which contaminate landfills. The natural gas is available and cost less than coal but there seems to be no push to change over. Why is that?