A study conducted at Yale School of Public health shows that air pollution contributes to higher levels of depression. According to the study, the increase of air pollution in China accounts for 22.5% of the actual decline in happiness in the country from 2007 to 2014. Additionally, the study found that this association was stronger in people who work outdoors, are more concerned with environmental problems, have young children, or earn lower incomes.

Lead author of the study, Assistant Professor Xi Chen, said that “air pollution heavily influences mental and emotional states. It heightens social inequality and is an important factor in a person’s sense of their overall welfare.”

The Yale study provides support for the Easterlin paradox, a concept in happiness economics that suggests that a higher level of a country’s per capita gross domestic product did not correlate with greater self-reported levels of happiness among citizens of a country, in contrast with people inside a country.

The study, published in the Journal of Environmental Economics and Management, compared a national longitudinal survey on happiness in China with air quality and weather information captured at the exact time and location the respondents were surveyed. Particularly, Chen used data on sulfur dioxide, particulate matter (PM), and nitrogen dioxide, as well as air temperature and precipitation.

According to the researchers, China is the best place to study the Easterlin paradox, because despite the unprecedented income growth generated from 1990 to 2010, China’s average happiness did not improve in that period of time. Additionally, 16 of the 20 most polluted cities in the world are in China, according to the World Bank.

For the method, the researchers decided using longitudinal data, as it captures the effect of changes in air quality on the same set of people over time, to find the connection between air pollution and mental health. Chen’s novel method was also able to distinguish between hedonistic happiness (happiness that varies from moment to moment) from evaluative happiness (which corresponds to an overall life satisfaction). In this regard, the results showed that air pollution had a major impact on hedonistic happiness, but it caused little change to measures of life satisfaction.

 

Source: Yale School of Public Health