Experts say that more than a decade of research — including two new studies out of California, and one on a Texas community — has made it clear that current setback distances, in states where they exist, are inadequate to protect public health. Now, political pressure to push oil and gas wells about half a mile from homes and other buildings is peaking across the country, over industry alarm that such measures could amount to a de facto ban on drilling.

In a move expected to result in years of legal wrangling, President Obama yesterday announced the most ambitious plan yet to sharply cut carbon pollution emitted by power plants.