Courtesy of The San Francisco Chronicle By Kari Nadeau

Jaxin Woodward is a 9-year-old runner from Vacaville, and she's already making a mark. Nationally ranked, she participates in Junior Olympic Track and Field.

"I like that you get to exercise," she says, "and I like that you just get to run and be free."

What makes her achievements especially remarkable is that Jaxin has asthma - severe asthma. She controls it with twice-daily medicine and careful monitoring. Her parents work with an asthma case manager to make sure their daughter stays safe. In a state where 90 percent of us live in areas with unhealthy air, staying safe can be a challenge.

As a pediatrician who specializes in asthma and allergies, I believe Jaxin is one small but precious reason among millions why adopting new pollution standards for cars is so important. Cars and trucks are the major source of the kinds of pollution, including smog and soot, that can trigger asthma attacks, heart attacks and other serious, and even deadly, health problems. Cleaning up vehicles is an essential part of cleaning up California's air.

A recent report from the American Lung Association in California finds that these new pollution standards, now being considered by the California Air Resources Board, could reduce our state's vehicle pollution-related health impacts - including asthma attacks, premature deaths, hospitalizations, and lost school and work days - by up to 70 percent. Add it all up, and we Californians could avoid more than $7 billion in health and other societal costs every year.

CARB's standards are designed to dovetail with the federal government's next round of fuel economy standards, which will require carmakers to increase miles per gallon in the years 2017-2025. Beginning in 2017, cars sold in California would require better smog and particle pollution controls, and meet higher greenhouse gas emission standards and requirements for zero-emission vehicles.

For Jaxin's mother, Da'Fona Jackson, a school psychologist, cleaning up what comes out of cars' tailpipes makes a lot of sense.

"It matters to us because the more pollution there is in the air the more medication she has to take, the more monitoring we have to do, the more there's a chance we have to increase her dosages to allow her to function like a child who doesn't have asthma," she said.

As a physician, I have seen the suffering firsthand. It is true that an ounce of prevention is worth a pound of cure.

Jaxin's mother describes witnessing a child's asthma attack this way: "She can't get a full breath. You see panic in her eyes. It strikes fear to your bones - there's something out there that you have no control over."

But we in California do have control over what we put into our air. We can insist on cleaner cars, and less pollution.

When you ask Jaxin what it's like to have an asthma attack, she replies, "I've never had one." The truth is, she has - but it was long enough ago that she has forgotten it.

Through careful monitoring and medication, she has not had an asthma attack in years - despite having a severe form of asthma, despite living in an area where air quality is not the best, and despite spending much of her free time outside, playing sports and running track.

It is a blessing that she cannot remember what it is like to have an asthma attack. Cleaning up California's cars can help make it increasingly less likely that she ever will.

Kari Nadeau is a volunteer physician with the American Lung Association in California and an asthma, allergy and immunology specialist at Stanford University Medical Center.