Long-term associations between ambient air pollution and self-perceived health status: Results from the population-based KORA-Fit study

Background: Little is known about the association between air pollution and self-perceived health (including both health-related quality of life [HRQoL] and self-rated health [SRH]). The aim of this study was therefore to explore whether long-term air pollution exposure is associated with worse self-perceived health, as measured by different tools.

Methods: We used a land-use regression model to determine the annual average levels of particulate matter with a diameter <10 μm (PM₁₀), coarse particles (PM_coarse), fine particles (PM_2.5), fine particle absorbances (PM_2.5abs), particle number concentration (PNC), ozone (O₃), nitrogen dioxide (NO₂), and nitrogen oxide (NO_X) for geocoded residential addresses (2014-2015). Questionnaires and face-to-face interviews were used to collect HRQoL (measured using the European Quality of Life 5 Dimensions [EQ-5D] index and the European Quality of Life Visual Analogue Scale [EQ-VAS]) and SRH indicators (measured through two survey questions) (2018-2019) from participants of the Cooperative Health Research in the Region of Augsburg (KORA)-Fit study in Germany. We explored associations via generalized additive models, multinomial logistic regression, and logistic regression.

Results: We included 2610 participants with a mean age of 64.0 years in this cross-sectional study, of which 1428 (54.7%) were female. Each interquartile range (IQR) increase in O₃ was associated with a reduced EQ-5D index value (% change of mean points and 95% confidence interval: -0.91% [-1.76; -0.06]). The average EQ-VAS score declined between -1.57% and -0.96% with each IQR increase in PM₁₀, PM_coarse, PM_2.5abs, PNC, NO₂, and NO_X. These pollutants were associated with increased occurrence of poor SRH, with odds ratios ranging from 1.24 to 2.67. PM_2.5abs was linked to a higher likelihood of reporting a worse comparative SRH (2.59 [1.12; 5.99]). Body mass index and self-perceived stress modified these associations.

Conclusions: Long-term air pollution exposure was associated with poor self-perceived health, presenting as lower HRQoL and higher odds of poor SRH. Single-item indicators measuring self-perceived health status may work better than multi-dimensional indicators.