Fig. 3: PM_2.5, PM₁₀, and CO₂ concentrations during the exposure sessions.

Average air pollutant concentrations across each exposure session for (a) PM_2.5; (b) PM₁₀; and (c) CO₂. Significantly higher concentrations of all pollutants were identified during particulate matter (PM) pollution exposure conditions compared to clean air, as determined by repeated measures ANOVAs with Bonferroni corrections: PM_2.5 [F(1, 25)  = 326.012, p  < 0.001]; PM₁₀ [F(1, 25)  = 418.035, p  < 0.001]; and CO₂ [F(1, 25)  = 292.685, p  < 0.001]. CO₂ concentrations were significantly higher in the normal inhalation condition compared to the restricted inhalation condition, as evidenced by a significant two-way interaction using repeated measures ANOVA with Bonferroni corrections [F(1, 25)  = 6.819, p  = 0.015]. n  = 26 independent human participants (biological replicates), within a fully repeated measures design. Median represented by the horizontal line, box indicates interquartile range (25th-75th percentiles), whiskers show full data range between minimum and maximum; white circles indicate individual data points; black diamonds indicate condition means; **p  < 0.01; ***p  < 0.001. Source data are provided as a Source Data file.