The fires are all but gone and the Sacramento Valley is finally enjoying a streak of clear skies and fresher air.
There's a new warning, however, for residents returning to outdoor activities: exercise well away from roads and freeways.
Pollutants from diesel exhaust are present in higher concentrations near roadways, and recent studies found people exerting themselves nearby can suffer severe, short-term lung damage.
California Air Resources Board scientist Susan Gilbreath this week outlined new findings that elevate the concern over what is a familiar story for area residents: Particulates, elemental carbon and nitrogen dioxide routinely assault the lungs of people in the region. What's now known to make matters worse is the threat of roadside air pollution to humans.
One study, conducted in metropolitan London, examined mildly to moderately asthmatic adults as they walked in a local park and along a heavily traveled roadway. Walking along the road for two hours, inundated with diesel exhaust, resulted in decreased lung function – three times greater than that observed after two hours in a park. Signs of inflammation were evident after the road walk – but mostly absent after exercise in the park.
"(Symptoms include) coughing, chest tightness, trouble breathing and also usually burning eyes and congested noses," said Bradley Chipps, a Sacramento pediatric pulmonologist and allergist.
Sacramento Valley residents may be doing themselves and the environment a favor by exercising outdoors and commuting on foot or bicycle, but it may be at a cost to their health. Decreased lung function means less oxygen to vital organs – a study of heart attack survivors exposed to diesel exhaust showed a threefold reduction of oxygen to the heart.
The air board's Gilbreath also described a study, originally funded by the ARB, which found children playing in a high-ozone environment were three times more likely to develop asthma.
Gilbreath suggested that residents alter exercise routes to avoid congested roadways. Chipps added that exercising in the morning, before the daily commute hours, is the best way to avoid noxious pollutants.
Or, area residents can seek out alternatives.
"Swimming is good – it's the least asthmagenic exercise that we know of. Or you can do a spinning or aerobics or some kind of class indoors," Chipps said.
Long-term benefits of exercise are alluring, but evading short-term consequences can be arduous.
"Regular activity has been shown to increase respiratory clearance, which should improve removal of inhaled particles from the lungs," Gilbreath said. The immune system improves with exercise, and "people who exercise use fewer sick days, have better cardiac and respiratory health, and live longer."
At an ARB meeting last week, a recurring concern was intensity of the exposure along roadways.
The London study found significant health impacts at a supposedly healthy concentration of particulates – 28 micrograms per cubic meter. The EPA standard for good air is higher – 35 micrograms per cubic meter, noted John Telles, an ARB member from the San Joaquin Valley Air Pollution Control District.
"Our current standard is, maybe, not good enough," he said.
Call The Bee's Maddalena Jackson, (916) 321-1041.
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