A new study confirms that lung problems get worse for Fresno asthmatics in winter when soot pollution increases. But, strangely, the same is not true during the worst summertime smog.
Surprised researchers say they think asthmatics simply stay indoors on hot, smoggy days. But on pleasant winter days when soot pollution sometimes spikes, people spend more time outside.
People with lung problems seem more aware of summertime pollution, said lead researcher Tim Tyner of the University of California at San Francisco-Fresno Medical Education Program.
"I think it means we should educate people more about particulate matter so they will know when it's wise to stay inside," said Tyner, associate director of clinical studies.
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Over the last 18 months, Tyner and pulmonologist Jose Joseph, associate professor of medicine at UCSF-Fresno, intensely studied the effects of pollution on nine Fresno residents who have asthma.
Chemist Alam Hasson and biologist Mamta Rawat, both from California State University, Fresno, also participated in the study. The research included a battery of physical tests to identify changes in lung functions and chemicals found in the asthmatics after air-pollution exposure.
The $250,000 study, underwritten by the San Joaquin Valley Air Pollution Control District, sheds light on a chronic lung problem in one of the nation's worst air basins.
Fresno County is California's asthma capital: Nearly one in three children -- or about 75,000 -- have it, according to one statewide health survey.
Researchers monitored the nine Fresno asthmatics during fall, winter and summer. In warm weather, asthmatics carried portable ozone monitors, so researchers would know how much pollution individuals experienced.
The portable monitors showed personal exposure was much lower than the ozone readings shown by the official air monitors in Fresno, largely because people were indoors much of the time.
But in winter, urine samples showed chemicals related to tiny specks of pollution, called PM-2.5, which are linked to reduced lung function. The chemicals triggered lung inflammation, Tyner said.
The chemicals come from vehicles, wood burning and meat cooking, according to the air district.
"The district is already moving in the direction of better controls of these chemicals," said David Lighthall, district health science adviser.
The district has enforced more wood-burning restrictions on polluted winter days, and new charbroiling rules for restaurants are under consideration. The district also is working on improving a program to retire high-polluting vehicles.
Tyner said researchers were unsuccessful in recruiting men for the study. But he said it was more important to find asthmatics who did not suffer allergies from pets, pollen, mold and dust, which are additional triggers for the ailment. Allergies would have created too much complexity in the study.
The research also included nine other women who did not have asthma. Tyner said the healthy women had fewer problems with PM-2.5 pollution, but they still suffered some narrowing of small airways in their lungs.
To confirm and expand on the findings, the researchers are planning a larger follow-up study involving 80 people -- 40 with asthma, and 40 otherwise healthy individuals.