The current Air Quality Index Scale, used to report daily air quality.
Next summer, the D.C. area is likely to have dozens more Code Orange days, and possibly more Code Red days as well. This isn't because the air will get dirtier, but because the Environmental Protection Agency will likely have tightened the definition of what healthy air is.
Right now, according to EPA rules, it's OK to have up to 75 parts-per-billion of ozone in the air. In 2008, a panel of EPA scientists unanimously recommended a lower limit: between 60 and 70 ppb.
But the agency, under the Bush Administration, opted for the more lax limit.
Under a new president and his new administrator, Lisa Jackson, the agency is considering a new limit, somewhere within the range originally recommended.
The D.C. area doesn't meet current air quality standards, so it won't meet the newer ones.
Jeff Holmstead, head of Environmental Strategy with Bracewell and Giuliani, says the stricter standards won't have much practical effect on air quality.
"All the things that states and local governments can regulate, they really have already regulated, and so the new standard is not really going to make that happen any faster," he says.
The costs of cleaner air, like emissions inspections on cars and rules regulating power plants, are already in place in the D.C. region, Holmstead says.
Environmental groups such as Earthjustice dispute that, saying the region could crack down further on power plants.
But what the new standard will certainly do is require a lot more other regions to address air quality.
"It's conceivable the whole country won't meet the new standard," Holmstead says.
That may mean new costs for other regions that have not had to pay for them like the D.C. region has. Holmstead says that will reduce the ability of certain regions to attract major new industries due to higher regulatory burden, but the D.C. region is not a major seat of industry and will be spared those effects, he predicts.
Joan Rohlfs, environmental program director with the Metropolitan Washington Council of Governments, says the broader reach of the new standard will be significant because the regions that produce air pollution aren't always the same ones who have to deal with it when it blows down wind.
Rohlfs says she would like to see more guidance from EPA and a multi-state plan.
"That's what's needed -- it's not going to be just local...actions on a Code Red day that are going to help us," she says.
Rohlfs says the new limits will offer more protection to public health.
In part, that's because the public will be warned, says David Baron, an attorney with environmental group Earthjustice.
"The days last summer we rated Code Yellow, many of those days would be under the new standard Code Orange, days people would be warned to stay inside because the air is dirty to breathe," Baron says.
He says that would help vulnerable individuals such as asthma sufferers.