Jeremy Siegel: This is GBH’s Morning Edition. Fall in New England is synonymous with getting outdoors: leaf peeping, apple picking, pumpkin picking, hay rides and hikes. With the heat and humidity going away and the crisper air bringing with it the change of the season, it’s a beautiful time to go outside. And research shows that it is good for you — physically, mentally and emotionally. Today, for our weekly deep dive into the weather and the science surrounding it with meteorologist Dave Epstein, we are going to talk about those benefits of getting outside and here alongside Dave for some additional expertise is Heather Eliassen, a professor at the Harvard T.H. Chan School of Public Health. Good morning to both of you.

Dave Epstein: Morning.

Heather Eliassen: Good morning.

Siegel: So, Professor Eliassen, I’ll begin with you. What do we know about what scientifically is behind why it’s so good to be outside? Like, why is it that breathing in fresh air, being in the sun, can actually help our physical and mental health?

Eliassen: Well, I think there are a number of reasons that could be underlying some of the relationships we’re seeing. Some of the things that we’ve been able to assess are factors like people who live in places where there’s more greenness actually have lower levels of inflammation and lower inflammatory markers in their blood. And obviously, physical activity is another benefit, and probably, you know, could be a link between green space and some of the health outcomes. So being close to green space encourages more physical activity. Green space could be destinations for walking and biking as well as spaces for play for children. And we know that physical activity is associated with a lot of health benefits, including reduced risk of many chronic diseases. But we also see that green spaces are associated with health benefits regardless of levels of physical activity. So some of those could be things like decreased stress, lower inflammation. And then that social interaction and community engagement, I think are also critical aspects of how green space can afford health benefits as well.

Siegel: Dave, you are someone who spends a lot of time in green space. Listeners will know that you are, in addition to being a meteorologist, a gardening expert. And you actually suggested this topic to us. What’s your own experience with the health effects of being outside?

Epstein: You know, it’s a multifaceted experience with it. I mean, there’s my own experience, just how I feel when I get outside. I know that if I’m in a mood that’s maybe a little depressed or just maybe a little bit stressed, if I can just force myself to get outside, that mood begins to change. If I can get my hands into the soil, if I’m just doing a little bit of weeding, if I’m taking a walk in the woods, I instantly feel better. And I give the same advice to folks that I might work with, whether it’s in an educational setting or a work setting, and also in work with kids — and my own son, when I want to have a difficult conversation, sometimes just being outside and walking around in nature enables those conversations to take place in a way that’s less stressful. So that also works well to be outside.

Siegel: Professor Eliassen, if someone can’t get to green space, or if you’re living in a big city like Boston, how should people try to make sure for their own health that they get outside?

Eliassen: There are opportunities probably in your neighborhood, so look into those opportunities. What are the green spaces that are easily accessible to you? And if there are some that are a short or medium distance from your home, you can walk or bike to the green space to get the benefits of exercise while you’re actually getting to the green space. Or find green space that you could incorporate into your commute to or from school or work. And, you know, some studies have shown even proximity to little pocket parks in urban environments is beneficial.

Siegel: Professor Eliassen, what qualifies as green space?

Eliassen: Well, that’s a great question. I think even anything from trees that are planted in the cityscape or grassy areas in the cityscape qualify as green space. So typically what we’re studying is greenness that we can see using satellite imagery, and actually sort of counting up the areas of green space.

Siegel: Dave, what ways does what’s happening outside factor into all of this?

Epstein: I think that even on cloudy days, we know that UV light is getting through the clouds. So you’re getting some vitamin D benefits, which also helps boost your immune system. When we eat plants, we know that it’s really good for us. But plants are also releasing some things into the air to protect themselves and kind of talk to other plants. We may be breathing some of that in, which also helps elevate our moods and actually can help our immune system. There’s some early research on that type of stuff going on. So I think it’s just a matter of it doesn’t matter what the weather is, just try to get yourself outside, even if it’s just a short amount of time during the day. Let that light let that nature really kind of bathe you. Take a forest bath.

Siegel: GBH meteorologist Dave Epstein and professor at the T.H. Chan School of Public Health, Heather Eliassen. Thank you both so much for your time on this.

Epstein: You’re welcome.

Eliassen: Thank you.

Siegel: You're listening to GBH News.

Fall in New England is synonymous with outdoor activities: leaf peeping, apple picking, pumpkin picking, hay rides and hikes. With the heat and humidity going away and the crisper air bringing with it the change of the season, it’s a beautiful time to go outside.

And research shows that spending time outdoors in green spaces is good for you — physically, mentally and emotionally.

So what counts as green space? It can be any space with grass, trees or other vegetation, said Heather Eliassen, a professor at the Harvard T.H. Chan School of Public Health. Forests are great, but you don’t have to travel too far to get the benefits. There’s value in spending time at smaller parks or playgrounds near your home, school or work.

“I think even anything from trees that are planted in the cityscape or grassy areas in the cityscape qualify as green space,” Eliassen said. “Some studies have shown even proximity to little pocket parks in urban environments is beneficial.”

Spending time in green spaces has been correlated with lower levels of inflammation and lower inflammatory levels in the blood, Eliassen said. Part of the reason may be that people for whom green spaces are more accessible tend to have an easier time being physically active.

“Being close to green space encourages more physical activity,” Eliassen said. “And we know that physical activity is associated with a lot of health benefits, including reduced risk of many chronic diseases.”

Even lower levels of physical activity outside can show some benefits, she said.

“We also see that green spaces are associated with health benefits regardless of levels of physical activity,” Eliassen said. “Some of those could be things like decreased stress, lower inflammation. And then that social interaction and community engagement, I think are also critical aspects of how green space can afford health benefits as well.”

GBH’s meteorologist, Dave Epstein, said spending time outdoors helps him feel well.

“I know that if I’m in a mood that’s maybe a little depressed or just maybe a little bit stressed, if I can just force myself to get outside, that mood begins to change,” Epstein said. “If I can get my hands into the soil, if I’m just doing a little bit of weeding, if I’m taking a walk in the woods, I instantly feel better.”

He also uses outdoor time to take the edge off conversations that might be stressful, he said.

“My own son, when I want to have a difficult conversation, sometimes just being outside and walking around in nature enables those conversations to take place in a way that’s less stressful. So that also works well to be outside,” Epstein said.

And those benefits can be there, even if it’s not a perfectly sunny day, he said.

“Even on cloudy days, we know that UV light is getting through the clouds,” he said. “You’re getting some vitamin D benefits, which also helps boost your immune system. … Just try to get yourself outside, even if it’s just a short amount of time during the day. Let that light let that nature really kind of bathe you. Take a forest bath.”