Pollution doesn't respect state boundaries. That was an underlying theme when the U.S. Senate debated whether to kill an Environmental Protection Agency rule that requires 27 Eastern states to curb smog and pollution that affect states downwind.
Kentucky Republican Sen. Rand Paul, who sponsored the proposal to eliminate the rules, characterized them as "job-killing regulations."
Rhode Island Democrat Jack Reed was one of the senators who argued for keeping them in place. He used an economic argument, saying that electric rates in other states are lower because polluters there simply send their dirty air high into the skies, forcing downwind states to spend extra on antipollution equipment when they generate their power or drive their automobiles.
That increases energy costs here, which drives up unemployment, Reed said. "We're effectively subsidizing lower electricity rates in parts of this country that are taking jobs from Rhode Island."
"Now in Rhode Island specifically, only 5 percent of ozone pollution is from local or in-state sources. Five percent. Ninety-five percent comes from outside of our borders, particularly the Midwest," Reed said.
The Paul proposal was ultimately defeated 41-56, mostly along party lines.
But we wondered whether the amount of imported ozone pollution is really that high.
Ozone is a form of super-oxygen, made up of three oxygen atoms. Normal, less-reactive, oxygen has two. High in the atmosphere, ozone is good. It acts as a natural sunscreen that shields us from damaging ultraviolet rays, which explains the concern over the "ozone hole" when it was growing in the Antarctic. But ozone near the ground is bad, a pollutant that causes breathing problems.
But is 95 percent of it blown in from other states?
The issue is complicated because the chemistry is complicated. Individual ozone molecules don't last long. They're generated by the right combination of sunlight, carbon-containing gasses (often called volatile organic compounds) and nitrogen-based pollutants (often called oxides of nitrogen or NOx). And the same pollutants that create it can, under the right conditions, destroy it.
"Consider the distribution of ozone around a source of NOx such as the interstate highway," said John Merrill, an atmospheric chemist at the University of Rhode Island. "On a day when the sun is shining, if you go a mile or two downwind, there's usually less ozone because the NOx emitted by the cars on the highway actually destroys ozone because there is way too much NOx relative to hydrocarbons. But if you go 20 miles downwind, there's still a little bit of NOx left and now it's producing ozone instead of destroying ozone."
When we asked Reed's office about the senator's claim, spokesman Chip Unruh sent us a 384-page technical document, released by the EPA in 1998, that deals with NOx emissions. It used wind data to see where that pollution came from, tracing it backward in time.
It reports that during high-pollution events, 5 percent of Rhode Island's dirty air comes from within the state and 95 percent derives from upwind states. Merrill said those are the most up-to-date numbers he could find. Those are the numbers Reed used.
Although the EPA report doesn't look at ozone directly and it's not accurate to equate NOx to ozone, Merrill said the percentages for ozone are pretty close because the pollutants follow the same wind-driven path. "It's the most important variable factor, other than meteorological factors."
So a cloud of ozone that grows on warm sunny days can migrate hundreds of miles before the sun goes down and the cloud starts to break down.
So which states are giving us all this pollution?
Reed said the primary source of the ozone is the Midwest.
Although Ohio, Michigan and some states to their west generate air pollution that drifts beyond their borders, the EPA report cited by Reed's office shows that the polluters that cause our ozone problems are much closer to home.
New Jersey is responsible for 30 percent of our air pollution; New York accounts for 24 percent, followed by Pennsylvania (12 percent) and Virginia (7 percent). Midwestern states such as Ohio, Illinois, Indiana and Michigan contribute no more than 11 percent.
"It follows the I-95 corridor," said Lenny Giuliano, an air quality specialist at the state Department of Environmental Management. "The wind has got to be in the right direction for us to get it."
Jack Reed said 95 percent of Rhode Island's ozone pollution comes from outside the state, and most of it is imported from the Midwest.
The percentages come from a 13-year-old EPA report -- the most recent available -- that looks at, not ozone directly, but the pollutants that generate ozone under the right conditions.
But the pollution sent into the air by smokestacks in the Midwest makes up only a small fraction of the pollution coming into Rhode Island, an amount overwhelmed by the dirty air coming from New York and New Jersey.
Because the first part of Reed’s statement is accurate and the second part is not, we’ll split the difference and rate his claim Half True.
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