PM2.5 "laid off" ozone into a Beijing primary pollutants
In recent days, Beijing sunny, temperatures remain high. But behind the high temperatures, prolonged occupation first PM2.5 pollutants in Beijing has been quietly "laid off", being replaced by ozone and its harm less than PM2.5.
Beijing environmental protection monitoring center forecast shows that primary pollutants are still today for ozone, air quality in mild to moderate pollution.
Fact sheet
Ozone pollution has been latent for days
Yesterday, the capital under weak pressure, high temperature diffusion disadvantages, primary pollutants are ozone air quality levels up to four levels of pollution. Today, the primary pollutant ozone is still in Beijing, between the four levels of mild to moderate pollution.
Starting from the 18th, Beijing primary pollutants into ozone. 18th at 14 o'clock, six to 57 μg/m3 PM2.5 hours concentration, at the same time, the concentrations of ozone at 185 mg/m. 19th at 14 o'clock, six ozone concentrations up to 236 μg/m3; 20th 14 o'clock, 241 mg/cubic metres of that data. 14 o'clock yesterday, which reached 242 μg/m.
According to the air quality standards, when the 1-hour average ozone concentration at the more than 200 micrograms per cubic meter, or when the 8-hour moving average more than 160 micrograms/cubic meter, means began to cause pollution. Environmental experts introduce Peng Yingdeng, unlike PM2.5 are, ozone likely cause acute injury to the human body.
Popular science
Summer afternoon ozone the most serious
Air quality report for the Ministry of environmental protection showed that in June, July and August, nearly half of Beijing-Tianjin-Hebei area pollution days, ozone instead of PM2.5 as primary pollutants. Introduction to municipal environmental protection monitoring center, Beijing from May to September when the temperature is higher, prone to excessive ozone pollution.
What does ozone pollution? Environmental protection experts, ozone usually exists in the upper atmosphere at about 30 kilometers off the ground, it can effectively block UV rays, protecting human health. But near the ground, ozone is a nasty pollutant, is a major component of photochemical smog.
Peng Yingdeng introduction, more suitable for generating photochemical pollution in the summer. Due to the high temperatures and strong ultraviolet rays, and motor vehicle pollutants, containing large amounts of nitrogen oxides and volatile organic compounds, under the Sun, occurs a series of reactions that generate ozone.
In the summer of intense sunlight, high temperatures, especially in the afternoon, prone to excessive ozone phenomena. High peak at around 13 o'clock to 14 o'clock, evening, concentrations decreased gradually.
Progress
Have begun to control ozone pollution
So, did begin to control ozone pollution in Beijing? Peng Yingdeng introduction, NOx and VOC (volatile organic compounds) are important precursors to ozone, therefore, the main methods of governance of photochemical smog, is to control both of these precursors. By contrast, vehicles produce nitrogen oxides, VOC, so non-heating season in high temperatures, good lighting, car is comprehensive sources of ozone pollution.
It is reported that the nitrogen oxide and VOC are included in emission inventories in Beijing. In addition, because both of these pollutants come from vehicle exhaust emissions, therefore, Beijing through ways such as raising fuel standards, control vehicle, but also to control ozone pollution.
Tips
Ozone irritation of the respiratory tract caused by tiredness,
According to the city environmental protection information center, ozone concentration, will have consequences for human health.
In particular, ozone can be intense irritation of the respiratory tract, and cause increased airway responsiveness and airway inflammation, asthma aggravation, and so on. Data show that when the concentration of ozone in the air between 0.01 and 0.02 mg/l, one can smell; up to 1 mg/l can be accelerated breathing, tightness in the chest; 2.5 to 5 mg/l can cause the pulse speed, tiredness, headache, stays in the environment for 1 hour, emphysema, severe life-threatening.
However, ozone monitoring is not easy. According to the Center, is monitoring data are not allowed, the second is controlling the "raw materials" emissions is difficult.
In addition, not less nitrogen oxide emissions of motor vehicles, generate less ozone. Because nitric oxide of nitrogen oxides in exhaust there is elimination of the effects of ozone, nitrogen dioxide ozone and VOC are produced by direct "raw materials", only the control in both an appropriate range, ozone generation is lowest. VOC sources is very wide, even plants may also be emitted, making it difficult to control.
Introduction to city environmental protection information center, to reduce the harm of ozone, summer afternoon out, if you don't open the window better.
In addition, where laser printers, such as in the Office, because laser printers including ultraviolet light, ionizing light produces ozone, and recommended that it be placed in a ventilated place.
For sensitive people must go out, Peng Yingdeng introduction on ozone in spatial and temporal distribution and PM2.5 were different. Time, prone on a summer afternoon; space, high value occurring in the suburbs. Go out to try to stagger to ozone "encounter".
Beijing News reporter Deng Qi
(Editors: Biao Guo UN832)
2016-05-22 02:06:02
The Beijing News
PM2.5默默“下岗” 臭氧成北京首要污染物
连日来，京城风和日丽，气温居高不下。殊不知高温背后，长期霸占京城污染物之首的PM2.5已默默“下岗”，被臭氧替代，且其危害不亚于PM2.5。
北京市环保监测中心预报显示，今日首要污染物依旧为臭氧，空气质量整体处于轻度至中度污染之间。
实况
臭氧污染已潜伏多日
昨日，京城受弱气压场作用，温度较高，扩散条件不利，首要污染物为臭氧，空气质量达四级中度污染水平。今日，京城首要污染物依旧是臭氧，为三级轻度至四级中度污染之间。
其实从18日开始，京城首要污染物就变为臭氧。18日14时，城六区PM2.5小时浓度为57微克/立方米，同一时间里，臭氧浓度达到185微克/立方米。19日14时，城六区臭氧浓度达236微克/立方米；20日14时，该数据为241微克/立方米。昨日14时，该数据达242微克/立方米。
按照空气质量标准，当臭氧1小时平均浓度超过200微克/立方米时，或8小时滑动平均值超过160微克/立方米时，意味着开始造成污染。环保专家彭应登介绍，跟PM2.5不同的是，臭氧容易对人体造成急性伤害。
科普
夏季午后臭氧最严重
环保部此前的空气质量报告显示，6月、7月和8月，京津冀地区的近半数污染日内，臭氧均代替PM2.5成为首要污染物。市环保监测中心介绍，北京5月到9月温度较高时，易发生臭氧超标污染。
臭氧污染究竟是什么？环保专家介绍，臭氧通常存在于距离地面30公里左右的高层大气中，它能有效阻挡紫外线，保护人类健康。但是在近地面，臭氧却是一种令人讨厌的污染物，是光化学烟雾的主要成分。
彭应登介绍，夏季更适合生成光化学污染。由于气温高且紫外线强，机动车排放的污染物中，含大量的氮氧化物和挥发性有机物，在太阳光照射下，会发生一系列反应，生成臭氧。
因此在阳光强烈、气温高的夏季，尤其在午后，易发生臭氧超标现象。一般高峰值出现在13时至14时左右，到傍晚时分，浓度逐渐降低。
进展
已开始治理臭氧污染
那么，北京开始治理臭氧污染了吗？彭应登介绍，氮氧化物和VOC（挥发性有机物）是臭氧的重要前体物，因此，治理光化学烟雾的主要方法，就是控制这两种前体物。相比而言，机动车既产生氮氧化物，还产生VOC，所以，在气温高、光照好的非采暖季，汽车是臭氧污染的综合污染源。
据悉，目前氮氧化物和VOC均已被列入北京的排放源清单中。另外，由于这两种污染物大量产生于机动车的尾气排放，因此，北京通过提高燃油标准、控制机动车保有量等方式，也有利于防治臭氧污染。
小贴士
臭氧刺激呼吸道引起疲倦等
据市环保宣传中心介绍，臭氧浓度超标，会对人体健康产生一系列影响。
具体而言，臭氧会强烈刺激呼吸道，引起气道反应和气道炎症增加、哮喘加重等。数据显示：当空气中臭氧浓度达0.01至0.02毫克/升时，人们就可闻到；达到1毫克/升时，可使人呼吸加速、胸闷等；2.5至5毫克/升可引起脉搏加速、疲倦、头痛，在这样的环境中停留1小时，可发生肺气肿，严重时有生命危险。
然而，臭氧的监控并不容易。据该中心介绍，一是监测数据不准，二是控制臭氧的“原料”尾气排放量很难。
此外，并非机动车氮氧化物排放量越少，臭氧生成就越少。因为氮氧化物等尾气中的一氧化氮有消除臭氧的效果，二氧化氮和VOC才是产生臭氧的直接“原料”，只有把二者都控制在某个适当的范围，臭氧生成量才最低。而VOC的来源又非常广泛，甚至植物也会排放，因此很难把控。
市环保宣传中心介绍，要减轻臭氧对人体的危害，夏季午后应减少外出，如果不开窗效果更佳。
此外，在办公室等有激光打印机的地方，因为激光打印机内含紫外光源，可电离强光产生臭氧，建议将其放置在通风处。
对于必须外出的敏感人群，彭应登介绍，臭氧污染在时空分布上与PM2.5明显不同。时间上，易出现在夏季午后；空间上，污染高值易出现在郊区。外出尽量错开跟臭氧的“邂逅”。
新京报记者 邓琦
(责任编辑：郭彪 UN832)
2016-05-22 02:06:02
新京报