Particulate Matter (PM₁₀) and Life Satisfaction: Links Across and Within Twin Pairs

Ambient air pollution, specifically particulate matter (PM10 and PM2.5), is a major environmental concern with well-documented links to health and life satisfaction. While the causal pathways and mechanisms underlying these associations are actively being researched, the contribution of genetic and environmental familial factors to these links remains largely unexplored. In this regard, emerging adulthood is intriguing, as young adults increasingly establish lives outside parental homes, allowing for greater separation of familial and individual-specific effects. To leverage this time window, we analysed data from 4,504 young adult twins in the TwinLife study (Mage=23.04 years, SD=0.82; Nmonozygotic=2,249; Ndizygotic=2,255), assessed up to six times between 2014 and 2022. Twin comparison analysis was used to decompose the population link between PM10 and life satisfaction to test whether the effect runs between families (between-pair) or within families (within-pair), and whether these effects are zygosity-, age-, and measurement-specific. The effect of PM10 on life satisfaction ran between families, suggesting that shared factors, such as indirect effects of familial SES or neighbourhood characteristics, may be of importance. In monozygotic twins, the between-pair negative effect of PM10 on life satisfaction strengthened with age (b=-0.006, SE=0.003) and year of measurement (b=-0.011, SE=0.004). Controlling for between-pair differences, the within-pair effect was significant within monozygotic twins (b=-0.088, SE=0.030), and not within dizygotic twins (b=0.006, SE=0.041), suggesting the possibility of genetic confounding and a small but quasi-causal relationship between PM10 and life satisfaction in young adulthood. Target interventions, thus, should include both addressing the specific factors shared by twin families and the development of emissions-reduction strategies.