麻豆传媒

Indoor air purification improved pulmonary health markers among children living in a region with severe air pollution, a cluster randomized trial showed.

Among 79 kids living in Mengzhou City in China, the time-weighted personal fine particulate matter concentration decreased by 45.14% during the air purification period (mean 21.49 μg/m³) compared with the sham air purification period (mean 39.17 μg/m³), reported Tiantian Li, PhD, of the Chinese Center for Disease Control and Prevention in Beijing, and Haidong Kan, PhD, of Fudan University in Shanghai, and colleagues.

Pulmonary function measures all increased -- ranging from nearly 6% to more than 18% improvement during the air purification intervention period, they noted .

Airway inflammation levels were also "generally alleviated after air purification," as fractional exhaled nitric oxide in the air purification group decreased by 22.38% (95% CI 2.27-42.48).

Li and Kan told 麻豆传媒 that their results were consistent with findings from several previous randomized controlled trials involving air purifiers, and "the magnitude of respiratory benefits estimated in our study surpassed those reported in previous studies involving and ."

"The respiratory benefits in children observed in our findings underline the importance of indoor air quality improvement to safeguard the respiratory health of children," they noted.

"Clinicians are advised to emphasize the importance of implementing air purification interventions in environments where children spend their time frequently, such as homes, schools, and daycare facilities, to reduce exposure to high levels of particulate matter pollution," they added. "Air purification intervention may help prevent the onset of allergic diseases (e.g., allergic rhinitis and allergic asthma) and contribute to the alleviation of respiratory symptoms among children."

The improvements in pulmonary function measures observed with the air purification intervention included:

• Forced expiratory volume in 1 second improved by 8.04% (95% CI 2.15-13.93)
• Peak expiratory flow improved by 16.52% (95% CI 2.76-30.28)
• Forced vital capacity (FVC) improved by 5.73% (95% CI 0.48-10.98)
• Forced expiratory flow at 25% to 75% of FVC improved by 17.22% (95% CI 3.78-30.67)
• Maximal expiratory flow at 75% of FVC improved by 14.6% (95% CI 0.35-28.85)
• Maximal expiratory flow at 50% of FVC improved by 17.86% (95% CI 3.65-32.06)
• Maximal expiratory flow at 25% of FVC improved by 18.22% (95% CI 1.73-34.70)

In an exhaled breath condensate (EBC)-based metabolic analysis, there were 41 metabolites that were differentially expressed between the air purification intervention group and the sham group. The differential metabolites were enriched in D-amino acid metabolism; β-alanine metabolism; histidine metabolism; pantothenate and CoA biosynthesis; alanine, aspartate, and glutamate metabolism; and phenylalanine, tyrosine, and tryptophan biosynthesis.

Several metabolites in EBC (i.e., L-tyrosine, oxypurinol, sebacic acid, and β-alanine) were found to potentially mediate the effect of the air purification intervention on respiratory outcomes.

This double-blind, crossover trial was conducted in China from April to December 2021 and included 79 healthy children ages 10 to 12 years (mean age 10.3, 48% boys). The intervention included multi-setting air purification (both classrooms and bedrooms), which was compared with sham purification in a two-stage intervention with more than 2 months (76 days) for each period and a washout period (88 days).

During the study period, the mean concentration of outdoor fine particulate matter at the school site was 32.53 μg/m³.

Limitations to the study included that its findings may not be generalizable to other populations, including those with chronic diseases. In addition, due to a lack of 24-hour monitoring, exposures in the outdoor environment and indoor environments other than classrooms may not have been accurately evaluated.

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