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Steven Mayer/ The Californian

A layer of summer smog hangs over the patchwork of cities and farms in the southern San Joaquin Valley near Bakersfield.

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Steven Mayer/ The Californian

Stephen Conley, an atmospheric scientist from UC Davis, flies over the southern San Joaquin Valley as part of an 18-month study to document the movement of onzone pollution.

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Steven Mayer/ The Californian

UC Davis scientist Stephen Conley prepares to take off from Meadows Field in Bakersfield as part of a $99.747 ozone study funded by the San Joaquin Valley Air Pollution Control District.

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Steven Mayer/ The Californian

Scientific equipment in the back of Stephen Conley's single-engine plane analyzes the level of ozone in the air as the plane passes through it.

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Steven Mayer/ The Californian

UC Davis scientist Stephen Conley pauses for a moment before taking off on one of several planned research flights. Conley documents ozone levels at various altitudes around Bakersfield to gain a better sense of how ozone transported from Asia may be mixing with the air we breathe in the southern valley.

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Steven Mayer/ The Californian

The city of Arvin at the southern terminus of the San Joaquin Valley has long struggled with high ozone levels.

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Felix Adamo / The Californian

The Tehachapi Mountains south of Bakersfield almost disappear into the smog in this photograph shot from Comanche Drive, east of Highway 178.

It was no pleasure flight. The plane soaring over Bakersfield in one of the most polluted air basins in the nation was on a scientific mission.

The men on board were searching for smog -- and it wasn't hard to find.

Attached to the wings of the single-engine Mooney TLS were plastic inlets that sucked air through scientific equipment loaded into the rear of the plane. The equipment, which can detect levels of ozone, or smog, in parts per billion, was wired to a computer resting on the lap of the plane's passenger. The laptop showed a fever chart -- a graphical representation of ozone levels -- in real time.

"Yesterday we got what we came for over Arvin," said Stephen Conley, an atmospheric scientist from the University of California, Davis, who was at the controls of the plane. "We detected 112 parts per billion at 1,000 feet above the ground."

Had that extreme level of ozone dipped to the surface, mixed with ground-level ozone and been detected by an official ground station near Arvin, it might well have triggered an exceedance, or violation, of the federal one-hour ozone standard of 125 parts per billion by volume.

Residents on this end of the valley have known for years that we live in an ozone nightmare, a hazy, lung-burning Hades that regularly lands us at the top of the nation's "worst air" list.

But what researchers like Conley are finding is that a significant portion of the ozone found in the southern San Joaquin Valley is not even produced in California.

China, the largest exporter of goods in the world, isn't just sending us TVs, furniture and other consumer products. It's also exporting smog.


Scientists have long known that smog flows down the valley from northern sources, including the San Francisco Bay Area. Scientists have estimated about 9 percent of our ozone comes from up north.

But Conley and many other scientists are amassing a considerable body of evidence that shows alarming levels of ozone are being transported at relatively high altitudes across the Pacific Ocean from China and other Asian countries and mixing with the air we breathe in Bakersfield, Arvin, Lamont. Delano and Fresno.

As China's use of fossil fuels has grown dramatically in recent years, so has its production of precursors, chemicals that when cooked by the hot summer sun become ozone, a corrosive gas linked to heart and lung illness and even premature death.

"There is strong evidence that pollution from Asia, mainly from China, is crossing the Pacific," said Seyed Sadredin, executive director of the eight-county San Joaquin Valley Air Pollution Control District. "It is transported at high altitude until it gets to the valley where it takes a dive."

And humans are not the only species affected by intercontinental air pollution. Several studies, including one published last year in "Biogeosciences," indicate that agricultural crop yields can be reduced by trans-boundary ozone in the Northern Hemisphere.

Sadredin cautions that more studies are necessary to duplicate previous findings and to more precisely determine the paths of imported ozone and the meteorological and topographical processes that deliver it to our doorstep.

But one thing is clear, he said. This research raises serious questions of fairness regarding the annual assessment of a $29 million pollution penalty paid primarily by valley motorists in their vehicle registration fees -- a cost borne each year when the district exceeds the federal standards.

If the valley air district can prove to the U.S. Environmental Protection Agency that exceedances in ozone standards are directly attributable to TBOs, or trans-boundary ozone, the district should be able to make a strong argument that it's unfair to level the annual multimillion-dollar smog penalty, Sadredin said.

"It's important to understand that this doesn't let us off the hook," he said. "We need to continue to reduce our emissions."

However, the valley already has some of the toughest air regulations in the country, he said, and the number of exceedances has been trending downward for years, thanks to cleaner-running cars, stiff regulations on valley businesses and changes in behavior by residents. There's no doubt that the valley's air is cleaner overall than it's been in decades.

Will valley air officials eventually be able to prove to the EPA that, were it not for dirty air transported from China and other off-shore sources, the valley would not have exceed the one-hour ozone standard at a particular time on a particular day?

That's the $29 million question.


Last June, the valley air district board approved a $99,747 contract with the University of California, Davis for Conley's 18-month study, which uses aircraft monitoring to help determine whether long-distance flows of ozone from Asia are mixing with valley air.

Several other important studies examining this China Syndrome have already been published in scientific journals.

A research study headed by Owen Cooper, an atmospheric scientist at the University of Colorado, used a network of four balloon-launch sites along the California coast, and more sites inland, to gather ozone readings at various altitudes. Published in 2011 by the Journal of Geophysical research, the study used ozonesondes, balloon-borne instruments that measure concentrations of ozone at different altitudes and broadcast the data back to researchers.

One might expect air blowing in from the Pacific to be fairly clean -- even pristine. However, in the free troposphere above 3 kilometers, or just under 2 miles in altitude, ozone precursors, or smog-producing chemicals, were found by Cooper's team. The main sources? China and international shipping.

But how can scientists determine the sources of smog or smog-producing substances that have travelled thousands of miles across oceans?

David Lighthall, the health and science adviser for the valley air district who coordinates TBO research, said tiny particles of soot carried by the wind within plumes of ozone contain elemental signatures that can pinpoint their place of origin.

"They can tell the difference between coal from India and coal from China," he said.

Cooper's study was limited by funding and time. Much more work needs to be done, he said, to get a handle on "what's coming in month by month, year after year."

There's no question that ozone and ozone-producing chemicals are being transported to California and the western United States, Cooper said. But what is the impact on already-polluted air basins like the southern San Joaquin Valley?

Studies suggest the impact can be huge.

"For average daytime conditions, we found no enhancements of lower tropospheric ozone in the northern Central Valley, but enhancements of 12-23 percent were found in the southern Central Valley," Cooper's study concluded.

In layman's terms, nearly one-quarter of Kern County's ozone problem may be attributable at times to off-shore sources, making it completely beyond local control. Add another 8 to 9 percent coming from upwind sources in California and it's hard not to conclude that south valley residents have limited influence over the very air we breathe.


In 1998, the valley portion of Kern County exceeded the federal one-hour ozone standard 29 times. From 2011 to the present, there have been zero exceedances in Kern. Valleywide, there were only two last year and three in 2011. Statistically, the valley appears to be headed in the right direction when it comes to taking responsibility for the smog we produce.

If the district can go three years without an ozone violation -- and so far this year, there haven't been any -- the EPA will lift the penalty. The extra $12 added to valley residents' vehicle registration fees generate about two-thirds of the $29 million penalty. The remaining one-third comes from large industrial businesses.

The money funds grants and incentives that help decrease emissions.

As we learn more about the transport of ozone from Asia, ocean-going ships and even Europe, it seems possible that the five exceedances over the past 32 months -- all which occurred in Fresno County -- might not have happened were in not for ozone transported from outside the valley.

Kerry Drake, a spokesman for the San Francisco office of the U.S. Environmental Protection Agency, said questions of fairness regarding the annual penalty are not out of line, especially in light of the clear progress the valley has made in reducing emissions.

Wording in the Clean Air Act, which governs air standards in the valley, may provide a rare exemption. Under Section 179B, if a region misses an attainment deadline but can show that the standard would have been attained had it not been for the effects of international emissions, then that area would not be subject to the federal penalties -- including financial penalties -- normally associated with such a violation.

Hypothetically, if the air district gathered the best peer-reviewed studies and put together a science-based proposal that could be presented to the EPA and the California Air Resources Board, it is conceivable, Drake acknowledged, that a convincing argument could be made.

But it wouldn't be easy.

"Let's say you have an exceedance on, say, Aug. 7, in Fresno," he said. "Can you prove, on that day, that you wouldn't have exceeded the ozone standard had it not been for ozone transported from Asia?"


There's a chance the eight-hour standard could be lowered from 75 to 65 parts per billion, or even 60, making attainment in the valley a moving target.

David Parrish, one of the leaders in ozone research in the chemical sciences division of the National Oceanic and Atmospheric Administration in Boulder, Colo., argues that we mustn't pin all of our ozone problems on China. Without local production of ozone, very seldom if ever would impacted air basins like Los Angeles and the San Joaquin Valley be exceeding standards.

And our imported ozone is certainly not all coming from China, he said. Other Asian countries, Europe, international shipping and natural ozone sources all contribute, he said. In fact, ozone can circle the globe, so smog and its precursors created in the United States can similarly affect other nations.

However, Parrish said, the impact of imported ozone "is diluted as you move from west to east over North America."

Lighthall, the science adviser at the air district, said much of the research is still based on statistical inference and modeling. So more needs to be done, he said, especially if air officials are someday going to argue for an exemption from federal regulators.

"You need to have a good weight of evidence," he said. "A scientific case."