A common benchmark in the United States for determining when a driver is legally drunk is not doing enough to prevent alcohol-related crashes that kill about 10,000 people each year and should be made more restrictive, transportation safety investigators say.
The National Transportation Safety Board recommended on Tuesday that all 50 states adopt a blood-alcohol content (BAC) cutoff of 0.05 compared to the 0.08 standard on the books today and used by law enforcement and the courts to prosecute drunk driving.
"Most Americans think that we've solved the problem of impaired driving, but in fact, it's still a national epidemic," NTSB Chairman Deborah Hersman said.
The idea for a tighter standard is part of a safety board initiative outlined in a staff report and approved by the panel to eventually eliminate drunk driving, which accounts for about a third of all road deaths in the United States.
Hersman said progress has been made over the years to reduce drunk driving, including a range of federal and state policies, tougher law enforcement, and stronger advocacy. But she said too many people are still dying on America's roads.
The board acknowledged that there was "no silver bullet," but that more action is needed at the federal and state levels.
"In the last 30 years, more than 440,000 people have perished in this country due to alcohol-impaired driving. What will be our legacy 30 years from now?" Hersman asked. "If we don't tackle alcohol-impaired driving now, when will we find the will to do so?"
Lowering the rate to 0.05 would save about 500 to 800 lives annually, the safety board said.
Under current law, a 180-pound male typically will hit the 0.08 threshold after four drinks over an hour, according to an online blood alcohol calculator published by the University of Oklahoma. That same person could reach the 0.05 threshold after two to three drinks over the same period, according to the calculator.
Many factors besides gender and weight influence a person's blood alcohol content, and many states outlaw lower levels of inebriation when behind the wheel.
The NTSB investigates transportation accidents and advocates on safety issues. It cannot impose its will through regulation and can only recommend changes to federal and state agencies or legislatures, including Congress.
But the independent agency is influential on matters of public safety and its decisions can spur action from like-minded legislators and transportation agencies nationwide. States set their own BAC standards.
The board also recommended on Tuesday that states vastly expand laws allowing police to swiftly confiscate licenses from drivers who exceed the blood alcohol limits.
And it is pushing for laws requiring all first-time offenders to have ignition locking devices that prevent cars from starting until breath samples are analyzed.
In the early 1980s, when grass-roots safety groups brought attention to drunk driving, many states required a 0.15 BAC rate to demonstrated intoxication.
But over the next 24 years, Mothers Against Drunk Driving and other groups pushed states to adopt the 0.08 BAC standard, the last state falling in line in 2004.
The number of alcohol-related highway fatalities, meanwhile, dropped from 20,000 in 1980 to 9,878 in 2011, the NTSB said.
In recent years, about 31 percent of all fatal highway accidents were attributed to alcohol impairment, the NTSB said.
"I think .05 is going to come. How long it takes to get there, we don't know. But it will happen," said the NTSB's Robert Molloy, who helped guide the staff report.
For some, the vote struck close to home.
NTSB board member Robert Sumwalt noted that one of his relatives had been killed by a drunk driver and another is serving a 15-year sentence in a related death.
Many of the recommendations "are going to be unpopular," Sumwalt said. "But if we keep doing what we're doing, we're not going to make any difference."
The NTSB cited research that showed most drivers experience a decline in both cognitive and visual functions with a BAC of 0.05.
Currently, more than 100 countries on six continents have BAC limits set at 0.05 or lower, the safety board said.
The NTSB has asked all 50 states to do the same.