The authorities in the Chinese capital, Beijing, have issued their highest smog warning so far this year. The "orange level" alert declared on Sunday is the second highest possible, requiring factories to cut production.

中国首都北京的专家们，已经发布了迄今为止最高的雾霾警报。周日公布的“橙色级”警报是二级警报，并且有关部门还要求工厂减少生产。

Air pollution is a chronic¹ health-risk for those living and working in the capital and other major Chinese cities. Some reports suggest that visibility has fallen to a few hundred metres in some places.

空气污染对于在首都和其他主要城市生活和工作的人来说，是一种慢性健康风险。有报道指出，在一些地方，能见度已经下降到几百米。

At noon on Sunday, the air pollution monitor operated by the US Embassy in Beijing reported that the intensity² of the poisonous, tiny particles of PM 2.5 reached more than 400 micrograms per cubic metre in some of the worst-affected areas. The World Health Organization considers 25 micrograms per cubic metre to be a safe level.

周日中午，美国驻北京大使馆操作的空气污染监测仪显示，在一些受影响最严重的地区，可吸入颗粒物，即PM2.5，每立方米超过了400微克。而世界卫生组织认为安全范围是每立方米25微克。

Coal-powered industries and heating systems, as well as dust from construction sites, all contribute to the smog which has been exacerbated³ by humidity and a lack of wind.

煤炭工业和供热系统，以及建筑工地的灰尘，都会因湿度和风力减小而加剧雾霾的形成。

Air pollution is a perennial⁴ problem in China's northeast which is home to many heavy industries including coal mining. Earlier this month, China's state media and many residents criticised high pollution levels in the north-eastern city of Shenyang.

对于以煤矿为主能源的东北重工业基地，污染是个永恒的问题。本月早期，中国官方媒体和许多居民批评了中国东北城市沈阳的重度污染。

The People's Daily said PM 2.5 levels exceeded 1,400 micrograms per cubic metre. Activists⁵ said that may have been the "worst ever" air quality seen in the country.

人民日报称，沈阳的可吸入颗粒物，即PM2.5，达到了1400毫克每立方米。部分激进人士甚至表示，这是全国“最差”的空气质量了。

Earlier this year China's environment ministry⁶ announced that only eight out of the country's 74 biggest cities had passed the government's basic air quality standards in 2014. Most of the cities found to have the worst air were in the northeast.

今年早期，中国环境部宣布，2014年，在中国的74个大城市中，仅有8个达到了政府规定的基本空气质量标准。空气污染最严重的城市大多数都位于中国东北部。

China is attempting to cut pollution but still relies heavily on coal for its energy and industrial needs.

中国正在努力减少污染，但是目前仍然依靠煤作为主要工业能源。