Forests and Human Health June-25-2014

Increasing evidence of beneficial effects of nature on health

Liisa Tyrväinen, Professor, Finnish Forest Research Institute
Ann Ojala, Researcher, Finnish Forest Research Institute
Yuko Tsunetsugu, PhD, Senior Researcher, Forestry and Forest Products Research Institute, Japan

Stress is a growing problem in urbanized societies and modern living environments. At the same time, the potential for green areas to provide relief from stress and to improve living environments and quality of life has been more widely recognized. However, this knowledge is not yet properly integrated into land use policy and urban planning or in health care services. A joint Finnish-Japanese research project 'Stress-reducing quality of urban green areas' funded by the Academy of Finland and the Japanese Society for the Promotion of Science has produced knowledge about the qualities of green areas that generate stress-reducing outcomes in urban dwelling. This research has expanded further within “Green infrastructures for health in the future living environments” (GreenHealth) also funded by the Academy of Finland. The implementation of joint research results has been discussed together with practitioners and other stakeholders in national seminars. 

Field experiment in Helsinki

The main objective of this experimental study in Helsinki was to compare the effects of different urban environments on human well-being. This study investigated the psychological and physiological (salivary cortisol concentration) effects of short-term visits after working-days. The experiment was carried out during the years 2011-2012.

Viewing session in Helsinki city centre.

Viewing session in Alppipuisto.

Walking session in Keskuspuisto.

The volunteers visited three different types of urban areas: a built up city centre (as a control environment), an urban park (Alppipuisto) and urban woodland (Keskuspuisto), located in Helsinki, the capital of Finland. In all sites the participants had a 15 minute viewing session that was followed by a half an hour walking session.

The change in participants’ restorative experiences, vitality and mood was studied using self-reported scales. The physiological indicators were blood pressure, heart rate variability and salivary cortisol level. Additionally air temperature and humidity, as well as noise level and air pollution were measured during the experiment. 

The results indicate that the urban woodland and urban park relieve stress. The restorative effect appears quickly during the visit. The effect of the urban centre has the opposite effect, even though the volunteers spent a relaxing time there.

Compared to the feeling of restoration that the volunteers already felt after 15 minutes of sitting in the green environments, the feelings of new energy and vitality came later. The participants in the experiment felt more energetic after a half an hour walking session. The feeling of subjective vitality means to get new energy for every-day activities.
The salivary cortisol level dropped similarly in all urban sites.

The difference between urban green areas and the city centre is clear, but the difference between urban green areas is rather small. However, at the end of the experiment, the volunteers reported the forest to be the most suitable restorative environment for them. The restorative effect of urban green areas was probably quite similar because of the large size and good quality of green areas used in this study. The urban park (Alppipuisto) is one of the oldest and most beautiful parks in Helsinki with big trees, a fountain and varied vegetation. The urban woodland (Keskuspuisto) is the biggest urban forest in Helsinki, widely used for outdoor recreation.

Based on the research results, nearby nature should be used more for relaxation. City planning should guarantee an adequate supply of good quality natural environments. These environments are especially important for those residents who are mainly using public green areas.

Additional information

Tyrväinen, L., Ojala, A., Korpela, K., Lanki, T., Tsunetsugu, Y., & Kagawa, T. 2014. The influence of urban green environments on stress relief measures: A field experiment. Journal of Environmental Psychology, 38, 1–9.

Figure 1. The restorative effect of woodland and park already appears after 15 minutes.

 

Figure 2. In the forest and park, the volunteers experienced a higher level of vitality at the end of the experiment

The national co-operation includes the Finnish Forest Research Institute (Metla), the National Institute for Health and Welfare (THL), and the University of Tampere (UTA). The GreenHealth project aims to produce knowledge of the links between residents’ health and the nature spaces in housing and living environments. This knowledge can be applied in land use planning at municipality and strategic levels as well as in housing and environmental policies. More specifically, the objectives of this project are 1) to study the relationship between nature spaces in living environments and the health status of residents, 2) to study the physiological and psychological responses to short-term nature exposure, and 3) to study wellbeing, self-rated health and the use of various types of nature areas. The emphasis is also on the implementation of the research results. Recommendations and suggestions for the implementation of the results will be developed in close collaboration with stakeholders.

Field experiment in four forested and urban areas in Japan

The objective of the present study was to investigate the physiological and psychological responses to urban forest environments among 48 participants. To focus on the effects of the environment, a simple experimental design was employed where the participants viewed the landscapes quietly. We targeted the clarification of relatively short-term effects in accessible, managed urban forests, in order to contribute to the planning and design of urban green areas.

Fig.1 Locations and names of the test sites

Four forested areas and four urban areas located in the prefectures of Toyama, Nara, Hiroshima, and Oita were used as the test sites (Fig.1). The participants were 48 male university students who were recruited from local universities. The experiments took two days, during which each participant visited a forested area and an urban area in randomized order.

The participants were instructed to sit still in a chair and view the scenery at both the forest and urban sites for 15 minutes each. Systolic/diastolic blood pressure and pulse rates were measured before and after the period of viewing. Heart rates and their variability (HRV) were continuously measured during viewing. A paired t-test was conducted to compare the results obtained regarding forests and cities.

The heart rate is the number of the heart beats per minute, and the heart rate variability is the variation in the interval between consecutive heart beats. It has been demonstrated that beat-to-beat fluctuations in heart rate reflect rapidly reacting cardiovascular control systems, the sympathetic and parasympathetic systems, and that a spectral analysis of HRV is a powerful tool for the noninvasive evaluation of autonomic nervous system functions.

Fig.2 Pulse rate before and after viewing the sceneries in the forested and urban areas (Mean ± SD, N=46, **:p<0.01)

 

Fig.3 Time-course change of parasympathetic nervous activities (Mean ± SD, N=41-44, **:p<0.01)

Compared to the urban areas, the participants in the forested areas showed 1) significantly lower diastolic blood pressure before and after viewing the scenery, 2) significantly lower pulse rates before and after viewing the scenery (Fig. 2), 3) significantly lower heart rates during viewing, 4) significantly higher parasympathetic nervous activity analyzed from the HRV taken during viewing (Fig. 3), and 5) significantly lower sympathetic nervous activity analyzed from the HRV taken during viewing. With some exceptions, the indices were generally in excellent agreement with each other, suggesting that the forest environment possesses relaxing and stress-relieving effects.

We assume that these effects are due to a mixture of various environmental factors in forests, such as the scenery, sounds, smells, and touch, whether supraliminal or subliminal. A physiological approach is thus expected to significantly contribute to elucidating the relationship between forests and human health and wellbeing.

This study was conducted by the Forestry and Forest Products Research Institute in cooperation with Chiba University, Nippon Medical School, and the Finnish Forest Research Institute (Metla). The figures are cited from the article

Additional information

Tsunetsugu, Y., Lee, J., Park, B. J., Tyrvainen, L., Kagawa, T., Miyazaki, Y. 2013. Physiological and psychological effects of viewing urban forest landscapes assessed by multiple measurements. Landscape and Urban Planning, 113: 90-93.

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