Stress and mental health can directly affect productivity, and the cities that we live in play no small role in determining the amount of stress that we experience on a daily basis. In fact, a study done by ZipJet UK – a London-based organization that develops technology to reduce the stress in people’s lives – looks at the factors that contribute to the stress experienced from living in cities.

The study examines 17 factors that contribute to daily stress in cities around the world, ranging from demographic and geographic-based factors like population density and average amount of sunshine, to social and economic based factors like gender and racial equality and purchasing power. With a survey of 500 spaces in 150 cities, the study ranks the cities on a scale of one to 10 from “least stressful” to “most stressful,” giving each city an overall score out of 10.

The point of the study, according to ZipJet UK’s Managing Director Florian Färber, is “[to pinpoint] how the least stressful cities are managing this issue [and to teach] those cities struggling with a stressed out population [on how to] overcome it.”

Among the stress-inducing city-based factors is how access or lack of access to public transport contributes to urban stress. Topping the list is Singapore, which is one of the top-ranked cities when it comes to infrastructure and public transport and, accordingly, has lower transport-induced stress. Antananarivo, the capital of Madagascar, scored the lowest, which can be accounted for by its hilly landscape, political hiccups, and economic hardship, meaning that its lack of sustainable public transport induces a high level of stress for the Malagasy people.

Pollution-based factors also account for a portion of the study’s ranking. Contrary to the United States’ overall contributions to global air pollution, Miami stands as the city out of the 150 surveyed that induces the least amount of stress for its people when it comes to air pollution. However, for noise and light pollution, Miami was ranked 78th and 70th respectively, indicating that other kinds of pollution can play a role in creating stress as well.

Munich in Germany is the city with the highest purchasing power on the list, while Yaoundé in Cameroon has the lowest. In this statement, the Managing Deputy Director of the International Monetary Fund detailed the economic and political difficulties facing Cameroon that have caused the purchasing power of the Central African Franc to plummet, creating economic difficulties for the people of Cameroon – thus inducing economic stress.

While the study provides some insight into the sources of stress in cities around the world, it fails to distinguish between controllable factors that can be remedied, such as transport and infrastructure challenges, and less controllable factors, such as average yearly sunshine or natural disasters, for example. For cities that scored the lowest in terms of average sunshine per year, the stress of living in a gloomy city is somewhat inescapable.

The study also considers how racial and gender equality affect stress, placing San Francisco and Reykjavik respectively on top of those lists and Seoul and Baghdad at the bottom. And while these numbers match up when compared with the World Bank Report on Ethnic Inequality and United Nations Human Development Report, they may not necessarily be an accurate representation of how racial and gender (in)equality affect people in different socio-cultural contexts.

Previous studies have indicated that many factors contribute to the overall stressfulness of a city. A cross-disciplinary study titled “A systematic review of the relationship between objective measurements of the urban environment and psychological distress” published last year suggests strong linkages between the physical environment and psychological distress. According to the study, which was developed based on self-reported measures of psychological distress, features like graffiti, garbage, traffic and hazardous waste sites often act as visual cues and stressors for residents of a city.

Another study published in 2015 compared the level of mental disturbance among urban dwellers to their non-urban counterparts, finding that those who live in cities to be more paranoid than others.