I mean, if you walk past certain trees, they release chemicals called phytoncides that actually trigger the release of natural killer cells in your immune system.

我的意思是， 如果从某些树旁走过，它们会释放一种叫作植物杀菌素的化学物质， 这种物质能触疫统杀伤细胞的释放。

It also found phytoncides - chemicals emitted by trees - have an anti-microbial effect on humans, boosting our immune systems. Another study carried out a few years ago by Stanford University in the US, found similar benefits.

它还现植​​物杀菌素——树木释放的化学物质——对人体具有抗微生物作用，可增强我们的疫统。 美国斯坦福大学几年前进行的另一项研究现了类似的好处。