Reducing Traffic Pollution Exposure Improves Blood Pressure

Not Applicable

Completed

Conditions: Air Pollution

Interventions: Other: Air filtration and building envelop modifications

Registration Number: NCT04029129

Lead Sponsor: UConn Health

Brief Summary: This randomized trial assessed the effect of modifying building envelop and level of air filtration on blood pressure over two hour exposure sessions.

Detailed Description: Living close to major roadways is associated with elevated blood pressure (BP) amongst other adverse health effects. There is growing evidence that ultrafine particles (UFP, \<100 nm in diameter), which are elevated near major roads and highways, contribute to such risks. We assessed the efficacy of high efficiency particulate arrestance (HEPA) filtration and building envelope adjustment at reducing exposure to and health effects of air pollution next to major highways.

We used a randomized three-period crossover trial design to assign 77 participants (aged 40-75 and without diagnosis of hypertension) to three two-hour exposure sessions. Sessions were conducted in one of two rooms immediately adjacent to highways. High, medium and low exposures were attained by varying the degree of air exchange and amount of HEPA filtration in the room. During high exposure sessions, the room was ventilated with outdoor air and no filtration was used. During low exposure sessions, leakage of outdoor air into the room was minimized and HEPA filtration was maximized. During medium exposure sessions, a moderate amount of HEPA filtration was used (less than half of that used in low sessions). Indoor particle number and black carbon (BC) concentrations (i.e., markers of traffic-related air pollution) were monitored continuously.

During each session participants sat quietly and wore noise-cancelling headphones, while their BP was monitored every ten minutes using an ambulatory BP monitor. We monitored pulse and oxygen saturation continuously.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 77

Inclusion Criteria

The inclusion criterion was age 40-75 years.
There was a preference for people who were otherwise healthy, but overweight or obese.

Exclusion Criteria

A history of a major cardiovascular outcome (including myocardial ischemia (MI), stroke, angina)
Other serious health problems (current asthma or COPD)
Taking anti-hypertensive medications
Smoking or living with a smoker
Cognitive impairment
Working at a job with high combustion exposure (taxi/truck driver, restaurant cook)
High combustion exposure in the preceding 24 hours (driving on the highway, cooking in a restaurant, driving a truck)
Not speaking English or Chinese.

Study & Design

Study Type: INTERVENTIONAL

Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
Low exposure	Air filtration and building envelop modifications	Doors and windows were closed and sealed and full filtration was used to maximally reduce pollution in the room.
Medium exposure	Air filtration and building envelop modifications	Limited air filtration was used to partially reduce levels of pollution in the room relative to outside.
High exposure	Air filtration and building envelop modifications	Ambient air was allowed freely into the room.

Primary Outcome Measures

Name	Time	Method
Systolic Blood Pressure (SBP)	Over 2 hour exposure period, we measured SBP after 20 minutes with the objective to assess change in SBP in a time series of measurements over that time period.	Systolic blood pressure measured with ambulatory blood pressure monitors in mmHg.

Secondary Outcome Measures

Name	Time	Method
Diastolic Blood Pressure (DBP)	Over a 2 hour exposure period with the objective to assess change in DBP measured after 10 minutes in a time series of measurements over that time period.	The unit of measurement, mmHg for the diastolic blood pressure.