The Health Benefits of Indoor Air Filtration Among Children

Investigating the Health Benefits of Indoor Air Filtration Among Children: a Randomized Crossover Trial in Jiaozuo, China

This study aims to explore the health benefits of air purifier on the impact of air pollutants on children's health.

Study Overview

• Status: Completed
• Conditions: Protective Effect of Air Purifier on Children's Health
• Intervention / Treatment: Behavioral: Air Purifiers; Behavioral: Sham Air Purifiers

Detailed Description

From April 2021 to December 2021, researchers conduct a randomized double-blind crossover trial on about 100 healthy children in Jiaozuo City, Henan Province. The children are divided into two groups according to their classes and alternated the use of true or sham purifiers devices, including air purifiers and fresh air ventilation. Air purifiers are installed in the classroom and bedrooms of the children. Fresh air ventilation is installed in the classroom. A total of 4 epidemiological surveys are conducted on the subjects, with an interval of 60 days or more. All participants and research staffs were blinded to the group assignment. In addition, air pollutant exposure monitoring, questionnaire surveys, physical examinations, and biological sample collection are conducted on the research subjects each time. The biological samples are further tested for the concentration levels of related biomarkers such as the respiratory system, cardiovascular system, metabolic system, and nervous system. Furthermore, comprehensive evaluation of children's behavioral ability is also carried out. Ambient PM2.5 and indoor PM2.5 exposure concentrations are monitored in the study.

• Study Type: Interventional
• Enrollment (Actual): 105
• Phase: Not Applicable

Contacts and Locations

Study Locations

• China
  • Beijing, China, 100021
    • National Institute of Environmental Health, Chinese Center for Disease Control and Prevention

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 8 years to 12 years (Child)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• 10 ≤ 12 years old
• Volunteer to participate in this study

Exclusion Criteria:

• Current and past medical history, including asthma, childhood diabetes, childhood hypertension, behavior-related diseases
• Students who plan to transfer or move within six months
• Unable to cooperate with follow-up

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Air purifier; Participants in this group receive an intervention of real air purifiers placed in the indoor environment.	Behavioral: Air Purifiers; Students are divided into two groups: intervention group and control group. The intervention team places an air purifier in the indoor environment to intervene. All the indoor environment of the group use the same qualified air purifier, and all participants and research staffs are blinded to the group assignment.
Sham Comparator: Control; Participants in this group receive an intervention of sham air purifiers, we just remove the filter in the purifiers, and the other treatments are the same as the real purification group.	Behavioral: Sham Air Purifiers; The control group is also intervened. The intervention is to place a sham air purifier (remove the filter screen) in the indoor environment, and all the indoor environment use the same air purifier as the intervention group. All participants and research staffs are blinded to the group assignment.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes of FeCO	Use Pico Smokerlyzer to measure fractional exhaled carbon monoxide (FeCO). After deep breathing, the subjects held their breath for 15 seconds and then gently inhaled into the device. The instrument showed FeCO level and the estimated value of carboxyhemoglobin in blood.	Baseline and at the end of each 60 days intervention period
Changes of FEV1	The forced expiratory volume in 1 s (FEV1) is measured using a smart spirometer (Model A1, BreathHome, China) supervised by professional medical staff. Before the pulmonary function test, subjects will practice several times by themselves. During the examination, each subject stands and clamps the nose clip, and repeats the test, with the best result as the criterion. FEV1 reflect pulmonary function.	Baseline and at the end of each 60 days intervention period
Changes of FVC	The forced vital capacity (FVC) is measured using spirometer (Model A1, BreathHome, China). FVC reflects the expiratory resistance of large airways.	Baseline and at the end of each 60 days intervention period
Changes of FEV1/FVC ratio	The FEV1/FVC ratio is measured using smart spirometer (Model A1, BreathHome, China). FEV1/FVC ratio reflects the status of airway obstruction.	Baseline and at the end of each 60 days intervention period
Changes of PEF	The peak expiratory flow (PEF) is measured using smart spirometer (Model A1, BreathHome, China). PEF reflects airway patency and respiratory muscle strength.	Baseline and at the end of each 60 days intervention period
Changes of FEF25-75%	The forced expiratory flow at 25-75% of FVC (FEF25-75%) is measured using smart spirometer (Model A1, BreathHome, China). FEF25-75% reflects the small airway obstruction.	Baseline and at the end of each 60 days intervention period
Changes of MEF75%	The maximal expiratory flow at 75% of FVC (MEF75%) is measured using smart spirometer (Model A1, BreathHome, China). MEF75% reflects the terminal stage of expiratory flow rate.	Baseline and at the end of each 60 days intervention period
Changes of MEF50%	The maximal expiratory flow at 50% of FVC (MEF50%) is measured using smart spirometer (Model A1, BreathHome, China). MEF50% reflects the interim stage of expiratory flow rate.	Baseline and at the end of each 60 days intervention period
Changes of MEF25%	The maximal expiratory flow at 25% of FVC (MEF25%) is measured using smart spirometer (Model A1, BreathHome, China). MEF25% reflects the early stage of expiratory flow rate.	Baseline and at the end of each 60 days intervention period
Changes of FeNO	Use NIOX VERO Sensor to measure fractional exhaled nitric oxide (FeNO) as a biomarker for airway inflammation level. After deep breathing, the subjects gently inhaled into the device. The instrument showed FeNO level of the subjects.	Baseline and at the end of each 60 days intervention period
Changes of Blood Pressure	The professional staffs wrap the BP cuff around the left upper arm of children to measure BP using the Omron electronic sphygmomanometers (OMROM, J751). BP is measured at 2-minute intervals, with a total of three measurements taken. If the difference of BP values between the last two measurements exceeds 5 mmHg, additional measurements are performed. Each child is allowed to measure BP at least three times and up to five times. The BP indicators includes SBP, DBP, MAP and PP.	Baseline and at the end of each 60 days intervention period
Changes of heart rate variability	The trained staffs conduct a 3-minute comprehensive assessment using the handheld electrocardiographic recorder-CarePatch (ECG-H01, Hangzhou Proton Technology Co., Ltd., China) to measured HRV. The time-domain indicators include standard deviation of all normal-to-normal intervals (SDNN), the root mean square of successive differences between adjacent normal cycles (rMSSD), the percentage of adjacent NN interval differences greater than 50 ms (pNN50); and the frequency-domain indicators include very low frequency (VLF), low frequency (LF), high frequency (HF), the ratio of LF to HF (LF/HF). To eliminate possible error, subjects are conducted by the same trained staff using the same instrument.	Baseline and at the end of each 60 days intervention period
Changes of PR interval	The trained staff use a 12-lead electrocardiogram (ECG) monitor to measure the participants' the interval of the beginning of the P wave to the beginning of the QRS complex (PR interval).	Baseline and at the end of each 60 days intervention period
Changes of QRS duration	The trained staff use a 12-lead electrocardiogram (ECG) monitor to measure the participants' the interval of the beginning of Q wave to the end of the S wave (QRS duration).	Baseline and at the end of each 60 days intervention period
Changes of QT interval	The trained staff use a 12-lead electrocardiogram (ECG) monitor to measure the participants' the interval from the onset of the QRS complex to the end of the T wave (QT interval).	Baseline and at the end of each 60 days intervention period
Changes of QTc interval	The trained staff use a 12-lead electrocardiogram (ECG) monitor to measure the participants' the QT correction for rate (QTc interval).	Baseline and at the end of each 60 days intervention period
Changes of RV5	The trained staff use a 12-lead electrocardiogram (ECG) monitor to measure the participants' the amplitude of the R-wave in lead V5 (RV5).	Baseline and at the end of each 60 days intervention period
Changes of SV1	The trained staff use a 12-lead electrocardiogram (ECG) monitor to measure the participants' the S-wave depth in lead V1 (SV1).	Baseline and at the end of each 60 days intervention period
Changes of RV5+SV1	The trained staff use a 12-lead electrocardiogram (ECG) monitor to measure the participants' the sum of the R-wave amplitude in lead V5 and the S-wave amplitude in lead V1(RV5+SV1).	Baseline and at the end of each 60 days intervention period
Changes of academic performance	The assessment of academic performance consists of standardised scores (maths, chinese and total) and the relative rank of the scores within grade. Standardised scores are converted from raw scores (with minimum value of 0 and maximum of 100) according to the number of exams and classes, indicating the position of the sample value in the normal distribution curve, with higher value showing better outcome. Rankings are converted from place rankings of raw values, with lower value showing better outcome.	Baseline and at the end of each 60 days intervention period

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes of CRP	Detect the concentration of C-reactive protein in blood sample to examine the different level of inflammation between the group of intervention and control.	Baseline and at the end of each 60 days intervention period
Changes of 8-OHdG	Detect the concentration of 8-hydroxydeoxyguanosine (8-OHdG) in urine sample as a marker of generalized, cellular oxidative stress to DNA.	Baseline and at the end of each 60 days intervention period
Changes of metabolites in exhaled breath condensate	Collect the exhaled breath condensate and identify the metabolites of exhaled breath condensate using Ultra-high performance liquid chromatography-tandem mass spectrometry.	Baseline and at the end of each 60 days intervention period
Changes of the role of alertness	Alertness can be measured by the Attention Network Test and reflects an individual's acquisition and maintenance of a state of alertness to a particular type of information or target.	Baseline and at the end of each 60 days intervention period
Changes of the role of orientation	Orientation can be measured by the Attention Network Test and reflects an individual's selective attention to externally useful information.	Baseline and at the end of each 60 days intervention period
Changes of the role of conflict	Conflict can be measured by the Attention Network Test and reflects an individual's ability to process conflicting information.	Baseline and at the end of each 60 days intervention period
Changes of Wisconsin Card Sorting Test indicators	WCST contains absolute indicators of cognitive executive functioning which include level of conceptualisation, persistence and set maintenance. The cognitive absolute indicators include conceptual thinking includes complete correct (TC), complete error (TE), non-persistent error (NPE), conceptual level response (CLR) and category completed (CC), persistence includes persistent response (PR) and persistent error (PE), and pooling maintenance includes inability to maintain pooling (FM).WCST percentage metrics are similar in meaning to the absolute metrics, and can be categorised into the level of conceptualisation and the Two dimensions of persistence. Cognitive percentage indicators include conceptual thinking consists of total correct percentage (%TC), total error percentage (%TE), non-persistent error percentage (%NPE), and conceptual level response percentage (%NPE); persistence consists of persistent response percentage (%PR) and persistent error percentage (%PE).	Baseline and at the end of each 60 days intervention period
Changes of the position total number	The position total number is the number of all position-related stimuli during the N-back test. The subjects need to remember how each position changed and judge whether a duplicate position stimulus appeared after N rounds.	Baseline and at the end of each 60 days intervention period
Changes of the position number correct	The position number correct is the number of times during the N-back test that the subjects were able to correctly judge whether or not a repeated position appeared in N rounds. A higher number correct indicates that the tester performed better in remembering and recognising the location.	Baseline and at the end of each 60 days intervention period
Changes of the position percentage correct	Changes of position percentage correct is the accuracy of the -N-back test subjects in position-related tasks, expressed as a percentage. It is calculated as (number of locations correct ÷ total number of location stimuli) × 100%. A high rate of correctness indicates that the subjects' accuracy in location memory is high.	Baseline and at the end of each 60 days intervention period
Changes of the color total number	The color total number is the number of all colour-related stimuli during the -N-back test. The subjects were required to remember the colour changes and determine whether a repeated colour stimulus has occurred after N-backs.	Baseline and at the end of each 60 days intervention period
Changes of the color number correct	The color number correct is the number of times during the N-back test that the subjects were able to correctly judge whether a repeated colour appeared or not in N rounds. A higher correct count indicates that the tester performed better in colour memory and recognition.	Baseline and at the end of each 60 days intervention period
Changes of the color percentage correct	Changes of color percentage correct is is the subjects' accuracy in colour-related tasks during the N-back test, expressed as a percentage. It is calculated as (number of colours correct ÷ total number of colour stimuli) × 100%. A high rate of correctness indicates that the subjects' accuracy in colour memory is high.	Baseline and at the end of each 60 days intervention period
Changes of the shape total number	The shape total number is the number of all shape stimuli during the N-back test. The subjects need to remember the shape changes and judge whether a repeated shape stimulus has appeared after the N-back.	Baseline and at the end of each 60 days intervention period
Changes of the shape number correct	The shape number correct is the number of times during the N-back test that the subjects were able to correctly judge whether or not a repeated shape appeared in N rounds. A higher number correct indicates that the subjects performed better in shape memory and recognition.	Baseline and at the end of each 60 days intervention period
Changes of the shape percentage correct	Changes of shape percentage correct is the subjects' accuracy in shape-related tasks during the N-back test, expressed as a percentage. It is calculated as (number of shapes correct ÷ total number of shape stimuli) × 100%. A high rate of correctness indicates that the subjects' accuracy in shape memory is high.	Baseline and at the end of each 60 days intervention period
Changes of proteins in serum	Collect peripheral venous blood, extract the serum, and identify the proteins of serum samples using 4D-label free technology.	Baseline and at the end of each 60 days intervention period
Changes in biomarkers identified from other omics	Collect peripheral venous blood, exhaled breath condensate, urine, saliva, oral cells, oral swabs, nasal swabs, skin swabs, nails and feces samples, then identify the biomarkers by conducting transcriptomic, microbiome analyses, etc.	Through study completion, up to 10 years
Changes in other targeted biomarkers of interest	Collect peripheral venous blood, exhaled breath condensate, urine, saliva, oral cells, oral swabs, nasal swabs, skin swabs, nails and feces samples, then identify the other targeted biomarkers of interest.	Through study completion, up to 10 years

Collaborators and Investigators

• Sponsor: Tiantian Li
• Investigators: Study Director: Tiantian Li, National Institute of Environmental Health, Chinese Center for Disease Control and Prevention

Study record dates

Study Major Dates

• Study Start (Actual): April 10, 2021
• Primary Completion (Actual): December 15, 2021
• Study Completion (Actual): May 15, 2022

Study Registration Dates

• First Submitted: March 30, 2021
• First Submitted That Met QC Criteria: April 6, 2021
• First Posted (Actual): April 8, 2021

Study Record Updates

• Last Update Posted (Actual): September 24, 2024
• Last Update Submitted That Met QC Criteria: September 21, 2024
• Last Verified: September 1, 2024

More Information

Terms related to this study

• Other Study ID Numbers: 202032

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No