Cardiorespiratory responses of air filtration: A randomized crossover intervention trial in seniors living in Beijing: Beijing Indoor Air Purifier StudY, BIAPSY

•Air filtration can significantly reduce indoor air pollution levels.•Short-term indoor air intervention can be of limited health benefit in areas with extreme high outdoor pollution.•Health benefit of longer term intervention is worth investigation for vulnerable participants.

In this Beijing Indoor Air Purifier StudY (BIAPSY), we conducted a randomized crossover intervention trial in a panel of 35 non-smoking senior participants with free-living, with and without chronic obstructive pulmonary disease (COPD). Portable air filtration units were randomly allocated to active-(filter in) for 2 weeks and sham-mode (filter out) for 2 weeks in the households. We examined the differences in indoor air pollutant concentrations in 20 study homes and a suite of cardio-respiratory biomarker levels in study participants between filtration modes, with and without adjustment for potential confounders. Following active filtration, we observed significant reductions from 60 ± 45 to 24 ± 15 μg/m3 in ten-day averages of indoor PM2.5 and reductions from 3.87 ± 1.65 to 1.81 ± 1.19 m− 1.10− 5 in ten-day averages of indoor BC, compared to sham-mode filtration. The major components of indoor PM2.5, including water soluble organics, NO3−, SO42 −, Zn2 +, Pb2 + and K+, were also reduced significantly by 42% to 63%. However, following active filtration, we only observed significant reductions on systemic inflammation measured as of IL-8 at 58.59% (95% CI: − 76.31, − 27.64) in the total group of participants and 70.04% (95% CI: − 83.05, − 47.05) in the subset of COPD patients, with adjustments. We were not able to detect improvements on lung function, blood pressure, and heart rate variability, following short-term intervention of two-week active air filtration. In conclusion, our results showed that indoor air filtration produced clear improvement on indoor air quality, but no demonstrable changes in the cardio-respiratory outcomes of study interest observed in the seniors living with real-world air pollution exposures.

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