External environmental causes of cancer are factors in the environment that increase risk of cancer such as air pollution, UV radiation and indoor radon.

外部环境致癌因素是指环境中导致罹患癌症的危险升高的因素，如空气污染、紫外线辐射及室内的氡等。

youdao

But I am concerned about the environment, particularly water and air pollution.

但是我担心环境，特别是水和空气污染。

youdao

But what about pollution in the environment, and specifically air pollution?

可是你有没有考虑过环境污染的原因，尤其是空气污染。

youdao

That is because cars produce local air pollution, which damages human health and the environment, and also produce greenhouse gases, which contribute to global warming.

ECONOMIST: Burning issue

The paper, Air Pollution in London, produced by the Assembly's Health and Environment Committee, reports 8.3% of deaths in Westminster are attributable to man-made airborne particles.

BBC: Nitrogen oxides

Lawyer Alan Andrews, of environmental organisation ClientEarth, said an estimated 4, 300 Londoners now died each year as a result of air pollution (29, 000 UK-wide, according to the Department for the Environment, Food and Rural Affairs).

BBC: News, London