Do you like walking in the forest or climbing the hill? Studies show that staying in a green place will make people feel comfortable and happy. But how about blue places? They include beaches, rivers, lakes and some other areas with water.

"There are a lot of studies on how green places help with people's health and feelings, but not many on blue places, " Mark Nieuwenhuijsen, a scientist says.

Are blue places good for people's health and feelings too? To learn about it, Mark and his team make a study. It takes three weeks. In the first week, 59 people spend 20 minutes each day walking along a beach in Barcelona, Spain. Then, during a different week, they spend 20 minutes walking along city streets. In the third week, they spend 20 minutes walking indoors. After each activity, the team uses some ways to assess(评估) people's feelings and health. Then they find that walking in blue places really helps a lot.

About 55% of people around the world now live in cities and there will be more in the future. It is important for people to build more blue and green places in our daily life.