Photochemical smog is strongest in urban areas with calm winds and dry, warm, sunny weather.

光化学烟雾在城市地区最强， 风平缓，天气干燥、温暖、阳光明媚。

You'd see a cloud of photochemical smog covering the planet.

你会看到一团光化学烟雾笼罩着地球。

Both industrial and photochemical smog combine manmade pollution with local weather and geography.

工业烟雾和光化学烟雾都将人为污染与当地的天气和地理因素结合在一起。

Both are key ingredients in photochemical smog, which is what had been plaguing LA.

两者都是光化学烟雾的关键成分，这是一直困扰洛杉矶的原因。

And while some ozone in the upper atmosphere helps shield us from ultraviolet rays, on the ground, this gas can form alongside secondary particles and create photochemical smog.

它们会发生反应，形成臭氧。虽然高层大气中的臭氧能帮我们阻挡紫外线，在地面，这类气体可能会和衍生性粒子一起形成，产生光化学烟雾。

Secondary pollutants found in photochemical smog can damage and weaken crops and decrease yield, making them more susceptible to insects.

光化学烟雾中发现的二次污染物会破坏和削弱农作物并降低产量，使它们更容易受到昆虫的侵害。

Photochemical smog and airborne particles from vehicle emissions affect many rapidly developing cities, from Mexico City and Santiago to New Delhi and Tehran.

车辆排放的光化学烟雾和空气中的颗粒物影响着许多快速发展的城市，从墨西哥城和圣地亚哥到新德里和德黑兰。