SMOKE SIGNALS

EPA Tightens Ozone Emissions Standards

The Environmental Protection Agency announced a regulation Thursday that would tighten smog-causing emissions, but stayed above allowances recommended by environmentalists and public-health advocates. The new national standard for ozone, a result of both chemical plant and tailpipe emissions, is now set at 70 parts per billion, down from the Bush-era 75 parts per billion. The scientific panel advising the EPA had previously recommended a standard between 60 and 70 parts per billion.