Nitrous oxide is stable at ground level but breaks down in the upper atmosphere to form compounds that trigger chemical reactions that destroy ozone.

一氧化二氮在地平面时是稳定的，但在高层大气中则分解而形成某种化合物，从而引发化学反应而破坏臭氧层。

youdao

That is not their fault, say scientists, who last month isolated the chemical changes that trigger aromatic magic when the meat is heated, the very magic that makes the sarnies so hard to resist.

科学家认为这不是那些人的错。上个月，科学家分离出肉加热后引起香气魔力的化学变化，正是这种魔力才令熏肉三明治难以抗拒。

youdao

The combination of unconditional laughter and yogic breathing is said to stretch muscles and trigger endorphins –the chemical in the brain known for its feel-good effect.

据说，无拘束的欢笑和瑜伽呼吸(方式）相结合能够舒缓肌肉，刺激一种脑内化学物质——内啡肽的产生，而这种物质能带产生使人感觉良好的效果。

youdao

Chemical sprays like air fresheners,hair spray, household cleaning products and even strong perfumes can also trigger an asthma attack.

VOA: special.2009.07.28

Now that's pretty far fetched and not many people would say that a pop tart should be a controlled substance and regulated by government, but there are some very interesting chemical properties associated with foods like this that trigger things going on in the brain that affect us in a very big way.

这多少有点牵强,而且也没有很多人会认为,这种果酱馅饼应归为管制品,并受到政府监管,但有趣的是这种食品,确实有一些特别的化学特性,它会作用于大脑并会对我们产生大的影响

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

Chemical sprays like air fresheners, hair spray,cleaning products and even strong beauty aids can trigger an asthma attack.

VOA: special.2010.09.07

For example, Zeneca has managed to switch the bt gene, which gives maize plants resistance to nasty insects, on and off using another chemical trigger.

ECONOMIST: Terminator genes

This can trigger a series of chemical changes in the body that lead to cancer.

BBC: Radon

In the works, though, is something much more exciting: The use of topiramate, an anti-convulsive drug, which shows potential to correct brain chemical imbalances that trigger the cycle of craving and reward.

FORBES: Lindsay Lohan To Enter 90-Day "Lock Down" Rehab - Will It Work?