Blood Pressure, Coagulation, Inflammation, Pulmonary Function
Conditions
Keywords
air pollution, air purification, intervention, randomized controlled trial, cardiovascular health, pulmonary health
Brief summary
This study aimed to evaluate whether a short-term indoor air purifier intervention improves cardiopulmonary health based on a randomized double-blind crossover trial
Detailed description
We conducted a randomized double-blind crossover trial among 35 healthy college students in Shanghai, China in 2014. These students lived in dormitories that were randomized into two groups and alternated the use of true or sham air purifiers for 48 hours with a 2-week wash-out interval.All participants and research staff were blinded to the group assignment. We requested all participants to stay in their dormitory room with the windows/doors closed throughout each 48-hour intervention period. We delivered foods and drinks to each room during the intervention period. All interventions started at 8 a.m. to avoid issues related to diurnal variation. We evaluated health endpoints and drew blood immediately after the completion of each 48-hour intervention. We measured 14 circulating biomarkers of inflammation, coagulation and vasoconstriction, lung function, blood pressure (BP), and fractional exhaled nitric oxide (FeNO).
Interventions
BEHAVIORALAir purifiers
The 10 dormitory rooms were randomized into two groups of 5 rooms each. One group used an air purifier placed in the center of the room for 48 hours corresponding to one weekend, followed by a 2-week washout period, and another 48 hours of using a sham air purifier under the same conditions. The other group simply reversed the order in which the real and sham air purifiers were used. All rooms used the same qualified air purifiers (model FAP04, 3M Filtrete), with the only difference being removal of the filter gauze in the sham purifiers. The air pollution auto-sensing feature of air purifiers was disabled in both groups. All participants and research staff were blinded to the group assignment. We requested all participants to stay in their dormitory room with the windows/doors closed throughout each 48-hour intervention period.
Sponsors
Fudan University
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
PREVENTION
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
18 Years to 26 Years
Healthy volunteers
Yes
Inclusion criteria
* Healthy college students aged between 18 and 26 * All the subjects should stay indoor almost the entire time, and stayed within the central urban area of shanghai during the wash-out period.
Exclusion criteria
* current smokers or ever smokers * chronic respiratory diseases * chronic cardiovascular diseases * acute infections * medication use in recent one month
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Circulating Biomarkers | Blood samples were drawn within one hour after the intervention, and lab analysis was completed in the next 10 days | Peripheral blood samples (5 ml) were drawn by a nurse, separated into serum and plasma, and stored at -80 ℃ within 30 minutes. We measured the levels of 14 circulating biomarkers: (1) 8 biomarkers of inflammation, including C-reactive protein (CRP), fibrinogen, P-selection, monocyte chemoattractant protein-1 (MCP-1), interleukin-1b, interleukin-6, tumor necrosis factor-α (TNF-α) and myeloperoxidase; (2) 4 biomarkers of coagulation, including soluble CD40 ligand (sCD40L), plasminogen activator inhibitor-1, tissue plasminogen activator and D-Dimer; and (3) 2 biomarkers of vasoconstriction, including endothelin-1 and angiotensin-converting enzyme. |
| Lung Function | Within 1 hour after the end of the two-day intervention | A respiratory physician measured forced vital capacity, forced expiratory volume in 1 second and peak expiratory flow of each participant using the JAEGER Masterlab equipment (Würzburg, Germany) that meets the American Thoracic Society criteria. The volume signal was calibrated at least once on a testing day with a 3.0 L syringe connected to the pneumotachograph in accordance with the manufacturers' recommendations. We instructed participants to perform at least three forced expiratory lung function maneuvers in order to obtain a minimum of two acceptable and reproducible values, and we recorded the best results. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Blood Pressure | Within one hour after the 2-day intervention | After sitting in a quiet room for at least 5 min, participants had their left upper arm BP measured by trained technicians using a mercury sphygmomanometer at least three times with 2-min minimum intervals between measurements. The second and third sets of readings were averaged to obtain systolic BP and diastolic BP. Pulse pressure was calculated as the difference between systolic BP and diastolic BP. If the differences among the three measurements were bigger than 5 mmHg, a new round of measurements were arranged. |
| Fractional Exhaled Nitric Oxide | within 1 hour after the two-day intervention | FeNO is an established biomarker of respiratory inflammation, and has been widely used in epidemiological studies because of its high sensitivity, specificity and non-invasive nature. We measured FeNO levels using a portable NIOX MINO machine (Aerocrine AB, Solna, Sweden) according to standardized procedures by the American Thoracic Society and the European Respiratory Society. |
Countries
China
Participant flow
Recruitment details
We recruited 35 healthy college students.
Pre-assignment details
We recruited 35 healthy college students and no one were excluded according to the exclusion criteria.
Participants by arm
| Arm | Count |
|---|---|
| Sham Purifiers The 10 rooms were randomized into two groups of 5 rooms each. This group used sham air purifiers with the only difference being removal of the filter gauze. | 17 |
| True Purifiers The 10 rooms were randomized into two groups of 5 rooms each. This group used true air purifiers. | 18 |
| Total | 35 |
Baseline characteristics
| Characteristic | Sham Purifiers | True Purifiers | Total |
|---|---|---|---|
| Age, Continuous | 24 years STANDARD_DEVIATION 2 | 21 years STANDARD_DEVIATION 2 | 23 years STANDARD_DEVIATION 2 |
| BMI | 21 Kg/m^2 STANDARD_DEVIATION 2.5 | 22 Kg/m^2 STANDARD_DEVIATION 2.5 | 22 Kg/m^2 STANDARD_DEVIATION 2.5 |
| Region of Enrollment China | 17 participants | 18 participants | 35 participants |
| Sex: Female, Male Female | 12 Participants | 13 Participants | 25 Participants |
| Sex: Female, Male Male | 5 Participants | 5 Participants | 10 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — |
| other Total, other adverse events | 0 / 35 | 0 / 35 |
| serious Total, serious adverse events | 0 / 35 | 0 / 35 |
Outcome results
Primary
Circulating Biomarkers
Peripheral blood samples (5 ml) were drawn by a nurse, separated into serum and plasma, and stored at -80 ℃ within 30 minutes. We measured the levels of 14 circulating biomarkers: (1) 8 biomarkers of inflammation, including C-reactive protein (CRP), fibrinogen, P-selection, monocyte chemoattractant protein-1 (MCP-1), interleukin-1b, interleukin-6, tumor necrosis factor-α (TNF-α) and myeloperoxidase; (2) 4 biomarkers of coagulation, including soluble CD40 ligand (sCD40L), plasminogen activator inhibitor-1, tissue plasminogen activator and D-Dimer; and (3) 2 biomarkers of vasoconstriction, including endothelin-1 and angiotensin-converting enzyme.
Time frame: Blood samples were drawn within one hour after the intervention, and lab analysis was completed in the next 10 days
| Arm | Measure | Group | Value (GEOMETRIC_MEAN) | Dispersion |
|---|---|---|---|---|
| Sham Purifiers | Circulating Biomarkers | C-reaction protein（CRP） | 926.3 ng/ml | Standard Deviation 1967.1 |
| Sham Purifiers | Circulating Biomarkers | Fibrinogen | 1122.2 ng/ml | Standard Deviation 280.1 |
| Sham Purifiers | Circulating Biomarkers | P-selection | 139.0 ng/ml | Standard Deviation 41.6 |
| Sham Purifiers | Circulating Biomarkers | Soluble CD40L ligand（sCD40L） | 1.4 ng/ml | Standard Deviation 1.6 |
| Sham Purifiers | Circulating Biomarkers | plasminogen activator inhibitor-1（PAI-1） | 54.9 ng/ml | Standard Deviation 16.7 |
| Sham Purifiers | Circulating Biomarkers | Myeloperoxidase（MPO） | 1579.4 ng/ml | Standard Deviation 772 |
| Sham Purifiers | Circulating Biomarkers | D-Dimer | 1174.6 ng/ml | Standard Deviation 817.2 |
| Sham Purifiers | Circulating Biomarkers | Angiotensin-converting enzyme（ACE） | 102.9 ng/ml | Standard Deviation 32.4 |
| True Purifiers | Circulating Biomarkers | Angiotensin-converting enzyme（ACE） | 101.1 ng/ml | Standard Deviation 31.9 |
| True Purifiers | Circulating Biomarkers | C-reaction protein（CRP） | 913.1 ng/ml | Standard Deviation 1734 |
| True Purifiers | Circulating Biomarkers | plasminogen activator inhibitor-1（PAI-1） | 41.5 ng/ml | Standard Deviation 20 |
| True Purifiers | Circulating Biomarkers | Fibrinogen | 1108.2 ng/ml | Standard Deviation 232.8 |
| True Purifiers | Circulating Biomarkers | D-Dimer | 1001.2 ng/ml | Standard Deviation 988.5 |
| True Purifiers | Circulating Biomarkers | P-selection | 129.4 ng/ml | Standard Deviation 39.3 |
| True Purifiers | Circulating Biomarkers | Myeloperoxidase（MPO） | 1261.4 ng/ml | Standard Deviation 659.4 |
| True Purifiers | Circulating Biomarkers | Soluble CD40L ligand（sCD40L） | 0.5 ng/ml | Standard Deviation 1.1 |
Primary
Lung Function
A respiratory physician measured forced vital capacity, forced expiratory volume in 1 second and peak expiratory flow of each participant using the JAEGER Masterlab equipment (Würzburg, Germany) that meets the American Thoracic Society criteria. The volume signal was calibrated at least once on a testing day with a 3.0 L syringe connected to the pneumotachograph in accordance with the manufacturers' recommendations. We instructed participants to perform at least three forced expiratory lung function maneuvers in order to obtain a minimum of two acceptable and reproducible values, and we recorded the best results.
Time frame: Within 1 hour after the end of the two-day intervention
Population: Ultimately, all 35 participants completed this study.This crossover study autonomically allows each subject to serve as his or her own control over time.
| Arm | Measure | Group | Value (GEOMETRIC_MEAN) | Dispersion |
|---|---|---|---|---|
| Sham Purifiers | Lung Function | forced vital capacity(FVC) | 3.0 L | Standard Deviation 0.7 |
| Sham Purifiers | Lung Function | forced expiratory volume in 1 s(FEV1) | 2.8 L | Standard Deviation 0.5 |
| True Purifiers | Lung Function | forced vital capacity(FVC) | 3.1 L | Standard Deviation 0.8 |
| True Purifiers | Lung Function | forced expiratory volume in 1 s(FEV1) | 2.8 L | Standard Deviation 0.5 |
Secondary
Blood Pressure
After sitting in a quiet room for at least 5 min, participants had their left upper arm BP measured by trained technicians using a mercury sphygmomanometer at least three times with 2-min minimum intervals between measurements. The second and third sets of readings were averaged to obtain systolic BP and diastolic BP. Pulse pressure was calculated as the difference between systolic BP and diastolic BP. If the differences among the three measurements were bigger than 5 mmHg, a new round of measurements were arranged.
Time frame: Within one hour after the 2-day intervention
| Arm | Measure | Group | Value (GEOMETRIC_MEAN) | Dispersion |
|---|---|---|---|---|
| Sham Purifiers | Blood Pressure | Systolic pressure | 106.0 mmHg | Standard Deviation 9.6 |
| Sham Purifiers | Blood Pressure | Diastolic pressure | 70.9 mmHg | Standard Deviation 8.6 |
| Sham Purifiers | Blood Pressure | Pulse pressure | 34.8 mmHg | Standard Deviation 5.4 |
| True Purifiers | Blood Pressure | Systolic pressure | 103.0 mmHg | Standard Deviation 10.2 |
| True Purifiers | Blood Pressure | Diastolic pressure | 67.9 mmHg | Standard Deviation 8.9 |
| True Purifiers | Blood Pressure | Pulse pressure | 34.8 mmHg | Standard Deviation 5.9 |
Secondary
Fractional Exhaled Nitric Oxide
FeNO is an established biomarker of respiratory inflammation, and has been widely used in epidemiological studies because of its high sensitivity, specificity and non-invasive nature. We measured FeNO levels using a portable NIOX MINO machine (Aerocrine AB, Solna, Sweden) according to standardized procedures by the American Thoracic Society and the European Respiratory Society.
Time frame: within 1 hour after the two-day intervention
| Arm | Measure | Value (GEOMETRIC_MEAN) | Dispersion |
|---|---|---|---|
| Sham Purifiers | Fractional Exhaled Nitric Oxide | 14.5 ppb | Standard Deviation 25.1 |
| True Purifiers | Fractional Exhaled Nitric Oxide | 13.3 ppb | Standard Deviation 20.6 |