NCT03500614 - The Use of Air Cleaners to Mitigate Cardiopulmonary Health Impact of Indoor Exposure to Particles and Phthalates

The randomized double-blind crossover trial includes two cohorts with different intervention and health examination settings and will be conducted in Beijing, China between November 2017-May 2018. The first cohort plans to include 70 healthy college students who live in school dormitories, which were randomized into two dormitory groups to receive either true or sham air cleaner treatment for 1 week and then alternate the treatment after a wash out interval of at least 2 weeks (But in the enrollment, only 57 students were recruited actually). All participants and research staff are blinded to the group assignment. All participants are encouraged to stay in the dormitory with windows/doors tightly closed throughout the 1-week treatment period as far as possible, whereas necessary outdoor activities such as attending classes and dining in school canteens are allowed. All interventions will start at noon on Tuesday or Thursday and continue to the next morning of Tuesday or Thursday to avoid issues related to diurnal variation. Real-time PM2.5 concentrations will be measured using portable monitors and airborne PM2.5 mass samples will be collected in air filters throughout the treatment period. Air and fine particle phase phthalates samples will be collected using glass sampling tube filled with XAD2 macroporous resin and PM2.5 air filters respectively during the last day (24 hours) of the treatment period. Health variables, including blood pressure, lung function, fractional exhaled nitric oxide (FeNO), will be evaluated and biological samples including morning urine and fasting blood will be collected immediately after the completion of each treatment period. Efficacy of air cleaner treatment to reduce indoor exposure to particles and phthalates and related improvements in cardiopulmonary health variables will be evaluated using professional statistical methods. The second cohort plans to include 30 healthy college students who will undergo extended treatment period covering the start, peak and end phases of smog episodes occurring in Beijing (To avoid dropout, 32 students were initially recruited). All interventions will start from the beginning to the end of typical smog episodes. PM2.5 exposure monitoring as detailed above will be performed throughout the treatment period and repeated health examinations will be conducted at time points corresponding to the start, peak and end phases of the smog episodes. Efficacy of air cleaner treatment to reduce indoor exposure to PM2.5 and related improvements in cardiopulmonary health variables throughout the smog episodes will be evaluated using professional statistical methods.