The level of carbon dioxide in the atmosphere is measured in parts per million (PPM).
大气层里二氧化碳含量的测量单位是ppm，即一百万体积的空气中所含二氧化碳的体积数。
Hitherto diesel contained up to 500 parts per million (ppm) of sulphur, but the new rules limit sulphur to 15 ppm.
目前，柴油中硫含量为500ppm，但新规定将其限制在15ppm。
23 out of 28 products – 82 percent – contained formaldehyde at levels ranging from 54 to 610 parts per million (ppm).
28件产品中的23件 - 82% -甲醛含量在54至610百万分率(ppm)之间。
A commonly cited goal is to stabilize GHG concentrations around 450-550 parts per million (PPM), or about twice pre-industrial levels.
一个共同的目标是使温室气体在空气中的浓度稳定在450- 550ppm(注二)，或者大约两倍于工业化前的水平。
All the methods give the same result: the concentration of oxygen is declining everywhere at the same rate, about 20 parts per million (PPM) per year.
所有这些方法都得到了同样的结论：地球上所有地方的含氧量正在以同样的速度(大约每年0.002%)减少。
In 2006, the FDA established a lead limit of 0.1 parts per million (ppm) in candy, based on the level the agency believed to be the lowest achievable.
2006年，FDA对糖果中铅的含量上限设定为百万分之0.1，基于这个标准的基础上这个机构相信这是最低含量。
Levels of the gas at the Zeppelin research station on Svalbard, northern Norway, last week peaked at over 397 parts per million (PPM), an increase of more than 2.5ppm on 2008.
挪威北部斯瓦尔巴群岛上的齐柏林研究站上周记录的二氧化碳气体水平最高值超过397个百万分点，比2008年的水平增加了2.5个百万分点。
The pre-industrial carbon dioxide amount was 280 parts per million (ppm). Humans, by burning coal, oil and gas, have increased this to 385 ppm; it continues to grow by about 2 ppm per year.
在前工业时代，二氧化碳含量为280ppm，人类燃烧煤炭和油气的行为使其上升到385ppm，而这一数值还在以每年2ppm的速率增长。
At 250 parts per million CO2, the shellfish grew vigorously, and at 750 PPM and higher they were crippled, feeble creatures with thin shells and weak connective tissues.
在CO2含量为百万分之250时，甲壳类生物生长得很好，而到了百万分之750或更高时，它们的甲壳变薄、连结物质变弱，成了残破而虚弱的生物。
To preserve a livable climate, we need to rapidly bring carbon-dioxide levels in the air back down below 350 parts per million (we are currently at about 387 PPM and rising fast).
为了保存一个富有生机的气候，我们需要马上把大气中的二氧化碳含量降到百万分之350(现在我们大约是百万分之387并且快速上升)。
The concentration of atmospheric carbon, an important indicator of global warming, has shot from 280 parts per million in pre-industrial times to 386 PPM last year and appears to be accelerating.
全球变暖的重要指示——大气的碳浓度——已经从工业社会前的280ppm (parts per million)激增到386 p pm，而且这一速度似乎还在增加。
Current concentrations of this dominant greenhouse gas have reached 390 parts per million — up from 280 PPM in recent pre-industrial times — and scientists tracking this buildup see no end in sight.
现今这种主要温室气体的浓度已经达到百万分之三百九十——高于工业化时代前的百万分之二百八十——并且科学家认为现阶段这个数字还将继续上涨。
If we continue to burn fossil fuels at current rates, levels of carbon dioxide in the atmosphere will reach 550 PPM (parts per million) — double pre-industrial levels — by around 2050.
如果我们继续按照目前的标准使用矿物燃料，到2050年全球大气中的二氧化碳含量将达到550ppm(百万分率)。这个数字是人类进入工业化社会前的两倍。
The reason may well be climate change caused by increasing concentrations of atmospheric greenhouse gases-now roughly 390 parts per million, up from 280 PPM in the 1700s.
导致这一现象的原因可能就是大气层中温室气体浓度增加引起的气候变化，目前大气层中的温室气体浓度已经从1700年的280ppm增加到现在的390ppm (ppm意为百万分之一，大概是指体积的比)。
The reason may well be climate change caused by increasing concentrations of atmospheric greenhouse gases-now roughly 390 parts per million, up from 280 PPM in the 1700s.
导致这一现象的原因可能就是大气层中温室气体浓度增加引起的气候变化，目前大气层中的温室气体浓度已经从1700年的280ppm增加到现在的390ppm (ppm意为百万分之一，大概是指体积的比)。
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