Cardiovascular Benefits of Air Purification in Children: Comprehensive Insights from a Randomized, Double-Blind, Crossover Trial

It remains uncertain whether and how indoor air purification improves children's cardiovascular health. We conducted a randomized, double-blind, crossover trial of midterm, all-day, multisetting air purification among healthy children in China to investigate cardiovascular benefits of mitigating fine particulate matter (PM_2.5) levels and explore potential biological mechanisms. The participants were cluster-randomized to the intervention or control group and experienced two 76-day exposure sessions separated by an 88-day washout period. High-resolution, real-time indoor PM_2.5 levels were monitored. The primary outcomes were blood pressure (BP), heart rate variability (HRV), and electrocardiogram (ECG); the secondary outcome was serum protein. Finally, 79 children were included in the analyses. We found that air purification could decrease BP (3.86-4.25 mmHg), shorten the duration of the QT and QTc intervals (7.23-9.17 ms), reduce the amplitude of RV5, SV1, and RV5 + SV1 (0.11-0.23 mV), and elevate the time- and frequency-domain indicators of HRV (9.62-14.89 ms, 26.42-32.11 ms², respectively). Proteomics analyses revealed that these benefits were associated with modulations in the pathways of oxidative stress, inflammation, endothelial damage, coagulation, and atherosclerosis. This trial provides evidence of the benefits of air purification on children's cardiovascular systems, offering valuable insights for protective strategies in highly polluted areas.