Ambient air pollution and the health-related quality of life of older adults: Evidence from Shandong China

Highlights

• Ambient air pollution was associated with lower HRQoL among older adults in China.

• Long term air pollution was associated with increased prevalence of pain and anxiety.

• The reduced HRQoL effects was exacerbated by higher socioeconomic status.

Abstract

Ambient air pollution is a major public health concern impacting all aspects of human health. There is a lack of studies on the impact of ambient air pollution on health-related quality of life (HRQoL) of older Chinese adults. Our study answers two questions: How concentrations of ambient air pollutants are associated with HRQoL among older adults in China and, second, what are the possible mechanisms through which ambient air pollution affects HRQoL. From the 2018 National Health Service Survey, we sampled 5717 aged 65 years or older residents for the eastern province of Shandong, China. Data on individual exposures to PM_2.5 and PM₁₀ (particulate matter with diameter less than or equal to 2.5 μm and 10 μm) and sulfur dioxide (SO₂) were collected from the ChinaHighAirPollutants (CHAP) datasets. Mixed-effects Tobit regression models and mixed-effects ordered Probit regression models were employed to examine the associations of long-term exposure to ambient air pollution with the European Quality of Life 5 Dimensions 3 Level Version (EQ-5D-3L) scale comprising mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Socioeconomic, demographic and behavioral factors relating to HRQoL were also examined. The results show that for each 1 μg/m³ increase, EQ-5D-3L scores fell 0.002 for PM_2.5; 0.001 for PM₁₀ and 0.002 for SO₂. Long term exposure to PM_2.5, PM₁₀ and SO₂ were also associated with increased prevalence of pain/discomfort and anxiety/depression. The reduced HRQoL effects of ambient air pollution were exacerbated by higher socioeconomic status (affluent, urban and higher level of education). Our findings suggested that HRQoL of older Chinese adults was not only associated with demographic, socioeconomic, and health-related factors, but also negatively correlated with air pollution, especially through increased pain/discomfort and anxiety/depression. The paper proposes policy recommendations.

Introduction

Accounting for over four million worldwide premature deaths annually, ambient air pollution is a major public health challenge (Collaborators, 2020; Shaddick et al., 2020; WHO, 2018). Numerous epidemiological studies observed a consistent association between long-term exposure to ambient air pollution and a range of chronic health effects, including respiratory diseases (Guarnieri and Balmes, 2014; Kurt et al., 2016), pulmonary diseases (Jiang et al., 2016), cardiovascular diseases (Brook et al., 2010; Hamanaka and Mutlu, 2018; Newby et al., 2015), mental disorders (Calderon-Garciduenas et al., 2002; Genc et al., 2012) and premature mortality (WHO, 2021). Older-aged people were found to be affected disproportionately to younger people by ambient air pollution (Simoni et al., 2015; Tibuakuu et al., 2018; Yin et al., 2020, 2021). While evidence of adverse health effects from long-term exposure to ambient air pollution among older adults is rapidly accumulating, most research focuses primarily on objective measures of health, such as mortality and morbidity (Hwang et al., 2020; Yamazaki et al., 2005). Such objective measures mainly assess the physical dimensions of health, failing to provide a complete picture of the burden of air pollution on older adults, including mental and social well-being, and not merely the absence of disease or infirmity (Dominick et al., 2002; WHO, 1946). Alternative indicators of the adverse health effects of air pollution on older adults, such as health-related quality of life (HRQoL), are necessary to assess the long-term health exposures to ambient air pollution. We address this research gap for China.

HRQoL is widely accepted as a valid and comprehensive measure of health status (Brown et al., 2013). HRQoL refers to a person's perception of his or her physical, mental, emotional and social functioning and wellbeing over time (Romero et al., 2013). It is usually assessed through a set of indicators across HRQoL's multiple domains. Since the early 1970s, various HRQoL metrics have been developed, including the Rand 36-Item Short Form Survey (SF-36) and the European Quality of Life 5 Dimension scale (EQ-5D), depending on the setting, such as clinical trials, healthcare system evaluation, health planning, and health insurance reimbursement decision-making (McHorney, 1999). In the field of environmental health, HRQoL has also been confirmed as an important measure of adverse health effects of air pollution (American Thoracic Society, 2000), linking the impact of ambient air pollution on individuals' multiple health domains (American Thoracic Society, 2000; Yamazaki et al., 2005). As HRQoL measures are generally independent of disease status, they enable us to measure health effects of air pollution across different populations. In addition, the use of preference-based measures of HRQoL facilitate the cost-benefits evaluation of alternative environmental policies targeting different air pollutants (American Thoracic Society, 2000; McHorney, 1999; Romero et al., 2013; Yamazaki et al., 2005).

Although the association between ambient air pollution and HRQoL is important for public health decision-making, surprisingly few researchers have quantified this relationship, especially for older populations. Using 3395 observations based on the SF-36 questionnaire, a Japanese ecological study found that higher concentrations of nitrogen oxides (NO_x) were correlated with lower scores in the “vitality” domain of SF-36 (Yamazaki et al., 2005). A small field study from Korea concluded that short-term exposure to fine particles (PM_2.5 and PM₁₀), nitrogen dioxide (NO₂), and ozone (O₃) causes respiratory symptoms leading to HRQoL deterioration (Hwang et al., 2020). A recent study, also from Korea, suggested an increase in the concentrations of PM₁₀, NO₂, carbon monoxide (CO), and sulfur dioxide (SO₂) were significantly associated with reduced overall HRQoL scores (Nakao et al., 2018). Regarding asthma-rhinitis, a large cross-sectional study in Europe found exposure to air pollution and lower greenness was associated with lower HRQoL scores in the domain of mental wellbeing irrespective of the asthma-rhinitis status (Siroux et al., 2021). Generally, existing studies have found evidence of adverse effects of air pollution on HRQoL. However, all studies were carried out in developed countries and most of them assessed only short-term effects. No study has explored the association between the long-term exposure to ambient air pollution and HRQoL in China.

We address this gap in the literature by using the three-level three-level EQ-5D (EQ-5D-3L) to measure HRQoL for older-age Chinese, examining the relationship between long-term exposures to ambient air pollutants and HRQoL. Our findings provide new empirical evidence for policy makers to guide their public health and environmental strategies to improve the quality of life for older populations. Specifically, we ask: were concentrations of ambient air pollutants associated with HRQoL among older adults in China? And, second, what were the possible mechanisms through which ambient air pollution affected HRQoL?