Particulate Matter Air Pollution and Life Satisfaction: Links Across and Within Twin Pairs.

Particulate matter (PM2.5 and PM10) air pollution is a major environmental concern with well-documented links to health and life satisfaction. While mechanistic pathways underlying these associations are being actively researched, the genetic and environmental sources of these links remain largely unexplored. In this regard, emerging adulthood is intriguing, as young adults increasingly establish lives outside parental homes, allowing for greater separation of shared familial and individual-specific effects. To leverage this time window and examine the role of shared and unique factors, 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 link between PM and life satisfaction to test whether the effect runs between pairs or within pairs, and whether these effects are zygosity-, age-, and measurement-specific. The effect of PM2.5 and PM10 on life satisfaction ran between families, suggesting that shared factors, for instance, familial SES or neighbourhood characteristics, may be of importance (b=-0.05, SE=0.01, p<.001). The between-pair negative effect of PM10 on life satisfaction strengthened with age (b=-0.00(4)-0.01, SE=0.00, p=.01-.03) and the year of measurement (b=-0.01, SE=0.00, p=.02-.05). After control for between-pair variation, within-pair associations with life satisfaction were not significant in dizygotic twins and significant at the nominal level for PM10 (b=-0.09, SE=0.04, p=0.04) but not for PM2.5 (b=-0.07, SE=0.05, p=.15) in monozygotic twins. Target interventions, thus, should include both addressing specific factors shared by twin families and emissions-reduction strategies.