Early this May, the Louisiana Department of Environmental Quality (LDEQ) did something it's never had to do before: It issued an alert for an "ozone action day" for elevated ozone pollution in New Orleans.

Chances are, it's the first of many.

"The EPA has changed the standards," says Rodney Mallett, a spokesperson for the LDEQ. "The air quality in New Orleans is just as fine as it was yesterday."

The summer months " with their furnace heat and tomb-still air " always see a spike in the amount of ozone pollution in the city. But this particular summer marks the first revision in more than 10 years in the Environmental Protection Agency's (EPA) standards for acceptable ozone levels. So it's not that New Orleans' air quality has taken a precipitous turn for the worse, but the LDEQ has been prompted to issue health warnings to the public when ozone levels are at lower levels than would have been considered a problem this time last year.

"Lo and behold, you're going to get more warning days," Mallett says.

Ozone is a gas that at high altitudes forms the much-needed protective layer we hear so much about in the global warming debates. Closer to ground level, however, ozone is less benevolent. It can be a caustic lung irritant that exacerbates all sorts of respiratory problems. In large quantities, it is more commonly referred to as smog.

The ozone compound is a secondary pollutant. When cars, factories or power plants put off emissions from any process that involves burning fossil fuels or organic compounds, these pollutants " volatile organic compounds (VOCs) and nitrogen oxides (NOXs) " can react with sunlight and transform into ozone.

"Sunlight hits it, the reaction begins and unless there's wind to disperse it, it accumulates," explains Jennifer Mouton with the LDEQ's Office of Environmental Assessment. Because sunlight and heat are the catalysts for ozone production, and Louisiana doesn't lack for either during the summer months, ozone is considered a seasonal pollutant.

Mouton and her colleagues at the LDEQ monitor the air quality across the state and report how much ozone, among other pollutants, is present in the air. Based on ozone measurement trends and meteorological data, scientists can forecast how much ozone will develop on a given day. That becomes the basis of the ozone alerts.

This monitoring is also part of what the EPA uses to determine whether or not a state is in compliance with regulations and has reached ozone attainment. With the notable exception of Baton Rouge, which is 10th on the American Lung Association's list of the most ozone-polluted cities in America, Louisiana has historically met ozone attainment requirements.

As a directive of the Clean Air Act, however, the EPA must review ozone standards every five years and consider revisions. The last change in standards prior to this March occurred in 1997. Looking at new research and a changing body of evidence about the health effects of ground-level ozone pollution, the organization tightened the restrictions on acceptable levels from 84 parts per million to 75 parts per million.

It sounds like a miniscule amount, but it's enough of a shift in the scale of acceptable ozone levels to warrant more alerts this summer and potentially risk New Orleans' ozone attainment status.

"We've always felt the standards were too high," says Tommy Lotz, CEO of the American Lung Association of the Mid South. "It would take a really high level of ozone for them to send out an alert. Now the standards are more realistic. We'll be able to diagnose more correlation between respiratory problems and air."

Like every other government warning system, the air-quality index for ozone is color-coded. Green means a good air day, yellow a moderate one, orange unhealthy for sensitive groups. It goes all the way up to code purple, which is presumably the color you would turn if it ever got that bad. There's no reason to think New Orleans will be hitting a code purple any time soon, but the city is expected to spend more time in the yellow and orange range. The more sensitive ozone alerts can be important warnings to people who may not have realized that air quality has been affecting their health all along.

"We know that ozone does cause lung injury in many experimental models," says Dr. Leonardo Seoane, a pulmonologist and associate program director in internal medicine at Ochsner Medical Center. "It causes inflammation, and then it causes scarring." That can lead to decreased lung capacity, decreased oxygen in the blood and increased strain on the heart.

Because of this pathway, those who are most at risk for health problems related to ozone exposure are people who already have vulnerable lungs or hearts. Children, the elderly, those who smoke tobacco and people with asthma, cystic fibrosis or emphysema are most prone to symptoms related to air pollution.

Certain groups of seemingly healthy people are at risk, too. People who work outdoors or spend a lot of time outside during the midday hours, when the sun is hottest and the ozone levels highest, are more likely to see long-term problems. The frequent, low-grade swelling and scarring of lung tissue could potentially lead to earlier onset of respiratory or heart illness.

"People with lung-health issues tend to go to the emergency room more," Seoane says. Studies of large cities have shown that, "on high ozone level days there are more deaths; there are more heart attack deaths and respiratory failure deaths," he says.

There tends to be a one-day lag between the day of high ozone in the air and the emergency room visits and deaths. Seoane suspects this is because people tend to wait a day before seeking medical help. Meanwhile, their symptoms and respiratory distress get worse. As might be expected of a lung irritant that is highest when it is hot and sunny, "all those increased deaths and increased hospitalizations go away in the winter," Seoane adds.

The lower thresholds for ozone warnings do not change how ozone impacts lung and heart health, Seoane says, but they do change how well people can monitor and prevent ozone-related health problems.

"It's just more about education," he says, adding that he sees the expected increase in ozone warning days as a way for people to assess their risk and prevent some of their own exposure. Also, if patients are aware of the relationship between air pollution and their health, Seoane hopes they will get medical attention sooner if they develop symptoms of pulmonary health problems.

'We need to educate our patients and educate the public," he says. That means encouraging people to stay indoors during peak hours of high-level ozone days. If someone must be outside, they should try to do it early in the morning or later in the evening when it's cooler and less sunny. People who work outside might want to consider wearing a simple, cotton face mask on high-ozone days, though if they work in construction or landscaping, they should be protecting their lungs with an appropriate face mask anyway.

Prevention also means cutting back on personal fossil-fuel-burning activities. Avoid driving at peak hours, don't mow the lawn in the middle of the day and try to carpool. In New Orleans, small measures like these can make a surprising difference.

"You can't have an ozone problem unless you have enough hydrocarbons," says Dr. Gary Miller, a chemical engineer and consultant to the Louisiana Environmental Action Network (LEAN). Miller, based in Baton Rouge, is personally and professionally familiar with the problem of ozone contamination.

'The difference between Baton Rouge and New Orleans is that (in Baton Rouge) ours comes primarily from our chemical and petrochemical plants," he says. New Orleans' mix of hydrocarbons is more influenced by automobiles and transportation-related burning of fossil fuels.

Like other experts whose jobs deal with ozone and air pollution, Miller sees the attention drawn to air quality as a positive outcome of changing EPA standards.

"The science has recognized we can reduce ozone in our cities, and there are positive reasons for doing that," Miller says. He points out that public health is just one aspect of it. There is financial incentive to reduce use of fossil fuels no matter what the environmental benefits are. The cost of health care for people who suffer from exposure to high levels of ozone is another reason to reduce output of the air contaminant. On a more indirect level, raising awareness of ground-level ozone pollution and preventing its development means reducing the accumulated cost of productivity lost to people taking sick days from work.

New Orleans' ability to maintain its ozone attainment status is important to government funding to the city as well. Under the new standards, "The DEQ has a year to decide if New Orleans is in or out of attainment," Mallett says. After the LDEQ makes its ruling, then the EPA has a year to come to a verdict. The outcome of attainment status under the EPA has a bearing on whether or not an area is subjected to economic sanctions like a loss of funds for federal highway projects.

"The bottom line is that it's becoming recognized it's worth it to fix the ozone problem," Miller says. "It's just cheaper in the long run and better for society in the long run."

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