Air pollution and absolute humidity tied to exercise-induced bronchoconstriction in children

Long-term exposure to air pollution is linked with asthma morbidity in children. Exercise-induced bronchoconstriction is common in asthma, and the free running test outdoors is a critical method for asthma diagnosis in children. There is no information on whether momentary air pollution exposure affects the results of outdoor exercise tests in children.

To fill this knowledge gap, Anna P. Tikkakoski, Tampere University, Tampere, Finland, and colleagues determined if brief air pollution exposure affects the results of outdoor exercise tests in children.

For this purpose, they analyzed all reliable exercise challenge tests with impulse oscillometry in 868 children performed between 2012 and 2015 at Tampere University Hospital. The investigators collected pollutant concentrations (NO2, O3, and PM2.5) during exercise from public registers. They compared the pollutant concentrations with the proportion and EIB severity and adjusted the analyses for pollen counts and air humidity.

The study revealed the following findings:

• Pollution levels were rarely high (median PM2.5 6.0 µg/m3, NO2 12.0 µg/m3, and O3 47.0 µg/m3).
• The relative change in resistance at 5 Hz after exercise did not correlate with O3, NO2 or PM2.5 concentrations.
• In multivariate logistic regression, we compared the effects of PM2.5 over ten µg/m³, absolute humidity (AH) over 10 g/m³ and alder or birch pollen concentration over ten grains/m³.
• High (over 10 g/m3) AH was associated with decreased incidence (OR 0.31), and PM2.5 over ten µg/m³ was associated with increased incidence (OR 1.69) of EIB.

"Even low PM2.5 levels may affect exercise-induced bronchoconstriction in children," the researchers wrote. "Of the other properties of air, only absolute humidity was associated with the EIB incidence."

About Exercise-Induced Bronchoconstriction

Exercise-induced asthma occurs when airways squeeze or narrow during strenuous physical activity. It causes coughing, wheezing, breathing, and other symptoms during or after exercise.

The medical term used for this condition is exercise-induced bronchoconstriction. Many asthma patients have exercise-induced bronchoconstriction, but those who do not have asthma can also have it.

Most people with exercise-induced bronchoconstriction can remain active and exercise if they treat their symptoms. Treatment includes asthma medicines and taking steps for symptom prevention before the physical activity starts.

Reference:

Tikkakoski AP, Tikkakoski A, Sipilä K, Kivistö JE, Huhtala H, Kähönen M, Karjalainen J, Lehtimäki L. Exercise-induced bronchoconstriction is associated with air humidity and particulate matter concentration in preschool children. Pediatr Pulmonol. 2023 Apr;58(4):996-1003. doi: 10.1002/ppul.26284. Epub 2022 Dec 28. PMID: 36530015.