In the process of fog and haze, optimistic netizens have created a lot of black humor. Tsinghua’s school motto has been changed to "being virtuous and self-improving, not breathing", but who can not breathe? In times of heavy pollution, we have to "serve the people". Very often, the prime culprit of smog is PM2.5. Surrounded by these fine particles, how much PM2.5 can we breathe in a day?

2.5. In case of severe pollution, several milligrams of PMXNUMX can be inhaled every day

When persistent haze weather occurs, the main air pollutant is PM2.5, which is fine particulate matter below 2.5 microns in diameter. Micron divides millimeters into 1000 parts. It can be seen that it is small because it can be inhaled into the human body and into the alveoli. If serious pollution occurs,The mass concentration of PM2.5 reaches 300 micrograms/cubic meter, then according to一天10~15立方米的呼吸量(详见下方注释),我们会大致吸入3~4.5毫克的PM2.5(1000 micrograms is 1 mg, 1000 mg is 1 gram). If you exercise a lot and have a higher pollution index, you will inhale more PM2.5.

Note: According to research, an adult, in a calm state, breathes about 500ml of air each time, breathing 16-20 times per minute, which is equivalent to 8-10 liters of air per minute.天将近11.5~14.4立方米。也有说法是在平和状态下,成年人每分钟呼吸6~7.5升空气,折合一天约8.6~10.8立方米。如果做一In some exercises, the breathing volume is greater. During strenuous exercise, the volume of air breathing can be about 10 times that in a calm state. Taking into account both theories, daily work life is more or lessFor these exercises, the daily breathing volume is about 10-15 cubic meters.

3. Smoked at least XNUMX packs of cigarettes during heavy pollution

The harm of PM2.5 is not limited to entering the alveoli and impairing the function of the respiratory system. PM2.5 also attaches some heavy metals and organic substances such as polycyclic aromatic hydrocarbons. According to research, the PAHs attached to PM2.5 are the same as some harmful substances in tobacco tar, including benzo[a]pyrene, etc., which are carcinogenic or carcinogenic.

Polycyclic aromatic hydrocarbons in tobacco tar generally account for 0.6% of tar. Calculated according to the tar amount of 10 mg per cigarette (the value is a medium to high tar content), the PAHs produced per cigarette are 60 ng (0.06 mg). In the paper "The Seasonal Changes and Source Analysis of Polycyclic Aromatic Hydrocarbons in Beijing Atmospheric Particulate Matter", it was pointed out that in the winter of 2006-07 in Beijing, the average concentration of PAHs attached to PM2.5 was 337.7 ng/m10, 15-day The respiratory volume of 3377 cubic meters is equivalent to 5065.5~56 ng, which is equivalent to smoking 84~3 cigarettes (about 4~XNUMX packs of cigarettes)! In addition, when smoking, some smoke diffuses into the surrounding air, so the actual amount of tar inhaled by the smoker is lower than the cigaretteThe above calculation result is the average level in the winter of 06-07. When heavy pollution occurs, the concentration of polycyclic aromatic hydrocarbons may increase on the above-mentioned basic value.This "one in and one out" means that when there is heavy pollution, our daily equivalent of "smoking" may be more!

Screen Shot at 2014 10-27-11.22.01

Note that the converted amount is not the average concentration of PAHs during heavy pollution, but the winter average of 06-07

Third, there are actually PM2.5 in daily life-choosing the right mask is very important

在我们日常制作美食的过程中,其实也会有PM2.5超标的情况!在一篇《烧鸡油炸烟气中PM2.5浓度及有害物质含量的测定》的论文中指出,实验表明,油 炸烟气中检出的PM2.5质量浓度为1275~2440微克/立方米。这是爆表水平的2-5倍了(世界卫生组织推荐安全标准是10微克/立方米,我国环境 空气质量标准二级限值75微克/立方米)。10个小规模的烧鸡加工企业排放的PM2.5与一个中小规模的热电厂相当。(好惊悚的赶脚,以后还能不能和小伙 伴一起开开心心吃炸鸡了?)

In addition, it should be noted that PM2.5 produced in kitchen cooking is oily particles. Even if you wear an N95 mask, it actually has no effect. Because the N series can only filter non-oily particles. At this time, you should choose P series mask protection (only for oily particles). In the actual atmosphere, PM2.5 particles include both non-oily particles and some oily particles (such as oil fume from asphalt). So if someone asks me, what kind of mask can take care of both and filter them together? I want to say: This guy is very lucky, and I just have a recommendation-FFP series. If you continue to ask, which FFP series of masks are more effective against smog? I only recommend the type, not the brand (and no one pays for advertising). Everyone chooses online. In short, wearing a mask is better than nothing.