Effect of Commute Traffic on Vascular Function

Study Overview
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Brief Summary
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The investigators will assess the vascular effects of riding in a car in heavily trafficked roadways, and whether filtering the car's air reduces those effects.

Detailed Description
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In this double-blind, crossover trial, randomized to order, recruited participants will be screened and then will accompany the study team on three typical commutes on separate days with sufficient washout (i.e., three weeks) between drives. One day this will occur with an effective filter system in the vehicle and the other two days without effective filtration; ineffective filtration is the most typical actual vehicle condition. Subjects will be unaware of the filtration conditions of the commute on that day. Each subject's experimental sessions will occur at the same time of day and will be separated by at least 21 days. The two sessions (either filtered air or traffic-derived entrained air) will be 120 minutes in duration and will encompass routes on heavily traveled roadways in the Seattle area. Before subjects begin the commute trials, they will go through the consent process and a series of screening tests. The study investigators will assess a series of measures regarding vascular function before and after each drive.

Official Title
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Effect of Commute Traffic on Vascular Function

Conditions
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Cardiovascular Diseases

Intervention / Treatment
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* Other: Filtered Air


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: healthy Exclusion Criteria: asthma, high blood pressure, diabetes, high cholesterol, other chronic conditions requiring ongoing medical care.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 49 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: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| No Intervention: Typical Commute<br>Participants spend two hours in automobile, on heavily trafficked roadways, without active filtration of air pollutants | |
| Other: Typical Commute, Filtered Air<br>Participants spend two hours in automobile, on heavily trafficked roadways, with active filtration of air pollutants | Other: Filtered Air<br>* The vehicle is fitted with a (High-Efficiency Particulate Absorbing, HEPA) filter device incorporating a charcoal filter, as well as an augmented cabin filter<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Brachial Artery Diameter from Pre-Drive to Post-Drive | Ultrasound assessment of brachial artery diameter, in millimeters. | 30 minutes before 120 minute driving session; 30 minutes post driving session | 
| Change in Blood Pressure from Pre-Drive to During-Drive and Post-drive | systolic and diastolic blood pressure measured in mmHg | 10 minutes before driving session; 15, 30, 45, 60, 75, 90, 100, 120 minutes following start of (120 minute) driving session; 10 minutes, 1.5 hours, 3.5 hours, 6 hours, 24 hours after end of driving session. | 
| Change in Retinal Arteriolar Diameter from Pre-Drive to Post-Drive | measured by retinal photography, image analysis, in micrometers | 30 minutes before 120 minute driving session; 30 minutes post driving session | 
| Gene Expression and DNA methylation | analysis in circulating mononuclear cells; determined via fold change in abundance | 30 minutes before 120 minute driving session; 30 minutes, 5 hour, and 24 hours post-driving session | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| circulating stress hormone | cortisol by chemiluminescence (ng/mL) | 30 minutes before 120 minute driving session; 5 hour and 24 hours post-driving session | 
| complete blood count with differential | laboratory values for hematologic indices (cells/uL) | 30 minutes before 120 minute driving session; 5 hour and 24 hours post-driving session | 
| inflammatory marker interleukin-6 | interleukin-6 determined by chemiluminescence (pg/mL) | 30 minutes before 120 minute driving session; 5 hour and 24 hours post-driving session | 
| inflammatory marker c-reactive protein | C-reactive protein by immunoturbidimetry (ug/mL) | 30 minutes before 120 minute driving session; 5 hour and 24 hours post-driving session | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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air pollution, traffic, vascular function, gasoline exhaust, diesel exhaust