kōng qì chà、huā fěn duō、gǎn mào shí kǒu zhào yǒu yòng，dàn gāo wēn tiān huì mēn

空气差、花粉多、感冒时口罩有用，但高温天会闷。

When the air is bad, pollen is high, or you have a cold, masks are useful, but they can be stuffy on hot days.