A third of children with asthma in the San Joaquin Valley miss a day or two of school each month, and the valley’s asthmatic children combined miss more than 800,000 days a year, according to a report from California State University, Fresno.

Researchers explored a variety of issues linked to asthma, an epidemic affecting school-age children in the eight-county region from Stockton to Bakersfield. Polluted air is a major factor in the frequency and severity of asthma symptoms in children, researchers said.

“I think we’re at a place right now where we know what some of the triggers for asthma are,” said Virginia Rondero Hernandez. “We know we have an air-quality problem, but we’ve yet to come up with a set of strategies.

“We need to keep talking about it because our kids are affected by this on a daily basis.”

Hernandez was lead investigator on the report, “Struggling to Breathe: The Epidemic of Asthma Among Children and Adolescents in the San Joaquin Valley.” She is associate director of research and evaluation at Fresno State’s Central California Children’s Institute, which issued the report Wednesday.

With an estimated 808,000 absences annually due to asthma, valley school districts lose at least $26 million a year in state attendance money, researchers found. Districts don’t get paid for absent students, even if they are sick. In Modesto City Schools, that’s about $30 a day per student.

Asthma is the No. 1 reason for school absences in Fresno Unified, said spokeswoman Susan Bedi. About 9,000 students were identified as having asthma last year, Bedi said, with 2,873 taking medication for asthma.

Students on preventive medication miss less school, Bedi said.

Not only is asthma costly to schools, it keeps students from learning and limits social, physical and emotional development.

“I think the effects are profound in the sense that depending on the number of days they miss, they’re missing academics they need,” Hernandez said.

In turn, parents miss work staying home with children having asthma attacks, she added.

Asthma significantly affects young people throughout the valley, with 15.8 percent of children younger than 17 diagnosed, compared to 13.6 percent diagnosed with asthma statewide.

Valley children and adolescents with asthma visit emergency rooms 25,000 times and are hospitalized 4,000 times a year, the study found. Researchers also found that asthma symptoms were not controlled well, even by medication, in more than 50,000 valley children and adolescents. Out of 87,000 young people taking asthma medicine, 60.6 percent still experience symptoms at least once a month.

Hernandez said she was shocked by the prevalence of asthma in the valley and the number of asthma attacks, despite medication.

Hernandez said she hopes that the institute’s report raises awareness of asthma’s effect on the valley’s young people and the need to find solutions, including better detection and tracking of young people with asthma.