The results are interesting because they indicate the psychological cost of living in heavily polluted areas, that come in addition to well-documented physical ailments, including suppressed lung growth and heart disease.

“Our results suggest a significant and negative association between mean annual ambient NO2 and life satisfaction, and moreover that these effects are substantive and comparable to that of many ‘big hitting’ life events,” researchers Sarah J Knight and Peter Howley write, in a paper titled Can clean air make you happy?

“For example, our standardised coefficients suggest that the effect of NO2 on life satisfaction is equivalent to approximately half that of unemployment, and equivalent to that of marital separation and widowhood, factors commonly associated with some of the largest wellbeing reductions in the literature to date.”

This one everyday factor affects happiness “as much as death and divorce”, new research finds