空气污染知多少:细数5大空气污染源

Air pollution from motor vehicles has, in many countries, replaced coal smoke as the major cause for concern; and the continuing growth in vehicle use means that efforts to reduce emissions from individual vehicles are in danger of being overtaken by increases in the volume of traffic.
机动车辆造成的空气污染在很多国家都已经超过了煤烟，成为了最大的空气污染源。持续增加的车辆使用数量也意味着：减少单部车辆排放的速度已经快要赶不上车流量增加的速度了。

The air pollutants produced as a result of the use of motor vehicles present a two-stage problem: primary and secondary pollutants. Primary pollutants produced by petrol-powered vehicles include carbon monoxide, nitric oxide, benzene, particulate matter and lead. Much of the lead emitted by vehicles burning leaded petrol emerges as particles. Secondary pollutants produced as a result of the use of petrol-engined vehicles include nitrogen dioxide and ozone.
机动车辆制造的空气污染会带来两个阶段的问题：一级污染物和二次污染物。一级污染物是由汽油动力车辆产生的，包括一氧化碳、氧化氮、苯、悬浮颗粒以及铅。很多消耗汽油的车辆所排放的铅最成为空气中的悬浮颗粒。二次污染物是由汽油引擎车辆产生的，包括二氧化氮和臭氧。

4. Domestic Sources
4. 生活污染源

As temperatures across the region plummeted, domestic burning of coal across northern China becomes the primary source of air pollution. Other important domestic sources of air pollution are:
由于温度骤降，中国北部地区的家庭中燃煤，成为了一个主要的空气污染源。其他重要生活污染源有：

Stoves and cookers produce carbon monoxide. If ventilation is inadequate or appliances poorly maintained, CO may accumulate in dangerous concentrations. Nitrogen dioxide is also generated and concentrations in kitchens will usually exceed those outdoors when cookers are in use.
炉灶会产生一氧化碳。如果通风不佳或设备维护不周，一氧化碳有可能会在家中聚集，达到会造成危险的浓度。同时还会产生的是二氧化氮，使用炊具时，厨房内的二氧化氮浓度会比室外的浓度高。

Bonfires, garden incinerators and barbecues can be a significant local smoke and odour nuisance. Burning garden waste produces smoke, especially if it is damp and smouldering rather than dry and blazing. The smoke contains CO and other noxious and irritating compounds. Problems may be caused for asthmatics, bronchitis sufferers or those with heart conditions. Even if the immediate health risk is small, bonfires add to the general background level of air pollution.
篝火、花园里的焚化炉和户外烧烤都有可能产生大量烟雾和难闻的味道。燃烧花园中的废弃物时会产生烟雾，特别是废弃物潮湿时，燃烧产生的烟雾要比干燥时产生的烟雾多。烟雾中还有一氧化碳和其他有毒、刺激性化合物。这些污染对有哮喘、支气管炎以及心脏疾病的人来说会造成不良后果。即使在短时间内没有很大的健康风险，篝火产生的污染也会增加大环境下的空气污染程度。

5. Agriculture
5. 农业污染

Agricultural practices can also be a significant source of nuisance, contributing both to local levels of air pollution and causing odour problems. The main sources of pollution are the burning of agricultural waste, or of crops in the field and large intensive livestock units. Depending on soil type and fertilisation, the nitrogen in the dung and urine of grazing cattle contributes 20-40% of nitrous oxide emissions from agricultural land; methane is also emitted by cattle and other ruminants; nitrous oxide and methane are of course both greenhouse gases.
农业活动也有可能成为讨厌的空气污染源，即会增加当地的空气污染程度，也会产生难闻的气味。农业污染最主要的的源头是焚烧农业废弃物、农田中的农作物，大量的牲畜也是一大农业污染源。牛的粪便和尿液是农业一氧化二氮排放的原因之一，根据土壤类型和土壤肥沃程度不同，其排放的一氧化二氮的比例会占到总量的20-40%左右。牛和其他反刍动物还会排放加完，而一氧化二氮和甲烷都是温室气体。