From VOA Learning English, this is the Health & Lifestyle report.

　　Are people happier in nature with blue skies overhead and fresh green grass underfoot? Could noisy streets, crowded with cars and people, make us unhappy?

　　The possible mental health effects of city living affects a lot of people. The World Health Organization estimates that 54 percent of the world's population lived in urban areas in 2014. The WHO adds that that amount will increase to 66 percent by 2050.

　　People often move to cities for better jobs and more cultural activities. But are they putting themselves at risk? Maybe.

　　Experts at the American Psychiatry Association say that "natural environments or green spaces" do much for good our mental health.

　　Many studies have shown that nature can calm us and make us feel happy. Nature, experts say, can also help us learn better. And experiencing nature helps people recover from the mental tiredness that comes from day-to-day work.

　　Other research also suggests that activity in natural outdoor settings can help to reduce the symptoms of Attention-deficit/hyperactivity disorder (ADHD) in children. ADHD is a brain disorder that can effect a person's ability to think clearly.

　　On the other hand, mental health experts say some research suggests that city living might hurt our mental health. But they cannot say exactly why.

　　"What are the specific aspects of the urban environment which causes some people to develop mental health issues?"

　　Andrea Mechelli is a doctor with the Institute of Psychiatry at Kings College, London.

　　"There have been studies where people were literally taken out of an urban environment into a rural environment, and their symptoms would improve. And we also see that the greater the city the greater the risk."

　　Mechelli says that someone who lives in a city is three times more likely to develop psychosis than someone who lives in the country.

　　Kings College researchers, along with city planners, land and building designers and others wanted to learn more about city living and mental illness. So, they created a smartphone app called Urban Mind. They say they wanted to understand how different parts of the urban environment affect mental wellbeing.

　　The Urban Mind app measures your experience of city living in the moment. Researchers collected real time information from 108 people. These people answered just over 3,000 questions during a one-week period.

　　The researchers found that "being outdoors, seeing trees, hearing birdsong, seeing the sky, and feeling in contact with nature were associated with higher levels of mental well-being."

　　They also found that these seeming effects of nature were especially strong in those individuals at greater risk of mental health problems.

　　The Urban Mind Project team says it hopes "the results will inform future urban planning and social policy aimed at improving design and health."

　　Their report is titled "Urban Mind: Using Smartphone Technologies to Investigate the Impact of Nature on Mental Wellbeing in Real Time." It was published in the January publication of BioScience magazine.

　　The researchers launched a new version of the Urban Mind app in March 2018. This new version will feature several languages and will be used for a large international study.

　　If you are interested in the project, you can visit the website at UrbanMind.info.

　　And that's the Health & Lifestyle report. I'm Anna Matteo.

　　Anna Matteo wrote this story using research from several websites including Urban Mind. The quotes are from Martin Secrest for VOA News.