Acute Health Effects of Traffic-Related Air Pollution Exposure

Study Overview
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Brief Summary
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This study aims to assess the effects of acute exposure to traffic-related air pollution and the underlying mechanisms.

Detailed Description
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The investigators will conduct a randomized, crossover trial among 72 healthy young adults in Shanghai, China. The eligible participants will be randomly divided into 2 groups (36 volunteers per group). During the first stage, participants will be requested to take one walking task (from 13:00 to 17:30). The exposed group will walk along a busy road and be exposed to traffic-related air pollution, while the control group will walk in a traffic-free park. During the first 3 hours, all participants will rest for 30 minutes after each 15-minute walking. From 16:00, participants will stop walking and rest for 1.5 hours. Then both groups will enter a 2-week washout period. In the second stage, there will also be one walking task (from 13:00 to 17:30). The two groups will exchange their walking sites and repeat the previous trial. Physical examinations will be performed both before and after each walking task. Besides, we will ask volunteers to stay in school during the two days before walking. Health examinations include symptoms questionnaires, blood pressure tests, Holter monitoring, and spirometry. We plan to collect blood, urine, oropharyngeal swabs, and exhaled breath condensate before exposure, about one hour after exposure, and next morning.

Official Title
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Acute Health Effects of Traffic-Related Air Pollution Exposure Among Healthy Young Adults: A Randomized, Crossover Trial

Conditions
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Cardiovascular System, Respiratory System

Intervention / Treatment
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* Behavioral: Walking along a busy road
* Behavioral: Walking in a traffic-free park


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Living in Shanghai during the study period; Body mass index > 18.5 and ≤ 28; Non-smoking, no history of alcohol or drug abuse; Completing the walking task we required. Exclusion Criteria: Current or ever smokers; Subjects with allergic disease, such as allergic rhinitis, allergic asthma, and atopy; Subjects with cardiovascular disease, such as congenital heart disease, pulmonary heart disease, and hypertension; Subjects with respiratory disease, such as asthma, chronic bronchitis, and chronic obstructive pulmonary disease; Subjects wih chronic disease, such as diabetes, chronic hepatitis, and kidney disease; Subjects with a history of major surgery; Abnormal spirometry (FEV1 and FVC ≤ 75% of predicted and FEV1/FVC ≤ 0.65); Medication use or dietary supplements intake in recent two months;

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 30 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Walking along a busy road<br>Participants in this group will be asked to walk along a busy road for 4.5 hours. | Behavioral: Walking along a busy road<br>* The intervention group will walk along a busy road and be exposed to traffic-related air pollution for 4.5 hours (from 13:00 to 17:30), while alternating 15-minute walking and 30-minute rest periods.<br>|
| Active Comparator: Walking in a traffic-free park<br>Participants in this group will be asked to walk in a traffic-free park for 4.5 hours. | Behavioral: Walking in a traffic-free park<br>* The control group will walk in a traffic-free park for 4.5 hours (from 13:00 to 17:30), while alternating 15-minute walking and 30-minute rest periods.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in FEV1 | We plan to measure changes in forced expiratory volume in 1 second. | FEV1 will be examined before exposure, half an hour after exposure and 12 hours after exposure. | 
| Blood Pressure | We plan to measure systolic blood pressure (SBP) and diastolic blood pressure (DBP). | Blood pressure will be measured for 24 hours from 8:00 am on the morning of intervention to 8:00 am on the next morning. | 
| Heart Rate Variability Parameters | We plan to measure heart rate variability (HRV) parameters. | Volunteers will be asked to wear electrographic Holter monitors for 24 hours from 8:00 am on the morning of intervention to 8:00 am on the next morning. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes of FVC | Changes of forced vital capacity | 7:00 AM on the day of the walking session, half an hour after exposure and 12 hours after exposure (next morning) | 
| Changes of FEV1/FVC | Changes of the ratio of forced expired volume in 1 second (FEV1) to forced vital capacity (FVC) | 7:00 AM on the day of the walking session, half an hour after exposure and 12 hours after exposure (next morning) | 
| Changes of MMEF | Changes of maximal mid-expiratory flow | 7:00 AM on the day of the walking session, half an hour after exposure and 12 hours after exposure (next morning) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Traffic-related pollution, Randomized controlled trial, Acute health effects