Table 1.

The pooled effect sizes (Hedges g) and 95% CI when comparing data before and after the activity in the natural environment.

Outcome	Effect size	95% CI	No. studies	Summary
Attention	0.23	(-0.30, 0.76)	3	No effect
Energy	0.76	(0.30, 1.22)	5	Improved
Anxiety	0.52	(0.25, 0.79)	6	Improved
Tranquillity	0.07	(-0.42, 0.55)	7	No effect*
Anger	0.35	(0.07, 0.64)	6	Improved
Fatigue	0.76	(0.41, 1.11)	4	Improved
Sadness	0.66	(0.16, 1.16)	3	Improved
Systolic BP	0.02	(-0.42, 0.38)	4	No effect
Diastolic BP	0.32	(-0.18, 0.82)	3	No effect
Cortisol	0.57	(-0.43, 1.57)	4	No effect*

The sign of the effect size reflects the benefit on health (positive effects indicate greater attention, energy and tranquillity but lower values for the other outcomes). 'Summary' describes the interpretation of the impact on health/well-being and an asterisk is used to denote a significant heterogeneity test (p < 0.05) for a particular group, indicating variation among studies. Number of studies reflects the number of studies for which there was data available to calculate this effect size (i.e with pretest data).