Perceived Stress, Residential Indoor PM2.5 Concentration, and Motor Vehicle Traffic Exposure Among Adults with Asthma: A Secondary Analysis.

Abstract

Background: Poorly controlled asthma creates a multitude of health, financial, and quality of life difficulties. The potential influences of environmental factors on the stress levels of people living with asthma-including exposure to fine particulate matter and motor vehicle traffic-are often overlooked.

Purpose: Among a sample of U.S. adults living with poorly controlled asthma, we aimed to determine (1) differences in perceived stress based on self-reported motor vehicle traffic exposure (MVTE), (2) differences in levels of residential indoor fine particulate matter 2.5 microns or less in diameter (PM2.5) based on self-reported MVTE, and (3) associations between residential indoor PM2.5 and perceived stress.

Methods: The National Institutes of Health (NIH) Symptom Science Model for Environmental Health served as the theoretical basis for this study, which is a secondary analysis of data from an NIH-funded feasibility study that examined the effects of residential indoor air quality on asthma symptoms and lung function in adults with uncontrolled asthma. This secondary analysis included data from the feasibility study's baseline survey of 40 participants and indoor PM2.5 data collected continuously over 14 days. Baseline survey data included demographic data, responses to the modified four-item version of the Perceived Stress Scale (PSS-4), and self-reported data on MVTE (dichotomized as low versus medium/high).

Results: Participants were primarily female (90%), White (82.5%), college educated (four-year degree or higher, 77.5%), residents of single-family homes (72.5%) in low-MVTE areas (70%), and 26 to 77 years of age. PSS-4 scores ranged from 0 to 14. Participants reporting medium/high MVTE had higher mean PSS-4 scores than those reporting low MVTE, although the difference was not statistically significant (6.5 versus 5.3, respectively; P = 0.305). The median level of indoor PM2.5 concentration (μg/m3) did not differ significantly regardless of whether the MVTE was medium/high or low (3.2 versus 3.6, respectively; P = 0.836). Higher PSS-4 scores were significantly correlated with higher average indoor PM2.5 levels (r = 0.38, P = 0.017).

Conclusions: Indoor PM2.5 reduction has important implications for stress management among adults with asthma. Further research is needed to clarify associations between MVTE and indoor pollution.