Children who are more exposed to green spaces tend to have lower oxidative stress, a new study has found.

Residential exposure to green spaces can have positive health effects, ranging from improved mental health and increased physical activity to lower risks of obesity and overweightedness, according to authors of a new study published in Environmental Research. There is also evidence that it may boost physical activity in both children and adults.

However, despite the growing body of evidence on the health benefits of exposure to green spaces, there hasn't been much focus on the actual direct effect of the exposure on biological processes, the Barcelona Institute for Global Health (ISGlobal) noted in a news release.

One such process is oxidative stress, which happens when there is an imbalance in free radical and antioxidant activity. When there are more free radicals that can be kept in check by the antioxidants, the free radicals can inflict damage to the body. This causes aging and even illnesses such as diabetes, neurodegenerative diseases and inflammatory conditions.

"Therefore, we aimed to assess the association between outdoor multisite greenness exposure and oxidative stress in children, and to explore the potential mediating role of physical activity in the mentioned association," the researchers wrote.

For their study, the researchers looked at 323 healthy children aged 8 to 11 who were recruited in Italy from March to May in 2017. School and residential "greenness" were defined based on the Normalized Difference Vegetation Index, while the children's oxidative stress was determined by urine samples. As for their physical activity, the parents provided the information via a questionnaire, ISGlobal noted.

The researchers found that the children with "higher greenness exposure" indeed had lower oxidative stress levels.

Judith Garcia-Aymerich of ISGlobal, the study's last author, noted that this could be because exposure to green spaces aids the children's immune development since they get exposed to organisms in these environments. The better air quality as well as the increased synthesis of vitamin D, which acts as an antioxidant, may also be possible explanations, Garcia-Aymerich further noted, as per ISGlobal.

However, the researchers did not find evidence that physical activity mediates the link between exposure to green spaces and oxidative stress. In other words, the association between exposure to vegetation and low oxidative stress is present "regardless" of the children's physical activity, ISGlobal noted.

According to the authors, the short- and long-term effects of oxidative stress in children remains "unknown." As such, this warrants "further investigation, and support city and public health strategies to green the environment.