In the winter, your lungs will burst! | Ohaus EX balance application case 
Winter smog
It’s really hiding and hiding.
The previous winter was white,
The winter is gray now.
Some cities are smoggy and locked in the city.
Leading to urban traffic restrictions and roads
The reason is... the car can't see the way out! !
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The smog has had such a big impact on our lives . What measures has China taken to prevent smog? When it comes to controlling haze, I have to say the criteria for judging haze:
In 2012, China issued the GB 3095-2012 Ambient Air Quality Standard. In this standard, the definition of ambient air is set, and PM2.5 is used as one of the detection qualities of ambient air!
The smog concentration value is determined according to the maximum transition period recommended by the WHO, that is, the annual average concentration limit is greater than or equal to 35 μg / m3; the 24-hour average concentration limit is greater than or equal to 75 μg / m3;
The standard has been implemented nationwide since January 1, 2016.
This standard specifies the manual analysis method for PM2.5, which is subject to the gravimetric method in the " Measurement Weight Method for PM10 and PM2.5 in Ambient Air in HJ618-2011 " .
The gravimetric method is the most direct and reliable method and is the benchmark for verifying the accuracy of other methods. So how do you measure it?
In simple terms, the sample is weighed before and after sampling with a balance of 0.01 mg precision, and the difference is obtained, and the smog concentration is obtained.
Note: Before and after sampling, the weighing of the filter should use the same analytical balance!
Part One
Next, Xiaoao takes everyone to see the specific experimental steps!
Processing filter
Select a suitable filter according to the purpose of sample collection, and it is required to have a retention efficiency of not less than 99% for 0.3 μm standard particles. First equip it in a constant temperature and humidity chamber for 24 hours.
The fibril filter paper stored in the dry box is at any point between 15 ° C and 30 ° C, and the relative humidity is controlled within the range of 45% to 55, and the equilibrium temperature and moderation are recorded.
Under the above equilibrium conditions, the filter was weighed with a 0.01 mg analytical balance and the filter weight was recorded.
The same filter membrane was weighed for 1 hour under the same conditions in a constant temperature and humidity chamber. For the PM2.5 sample filters, the weight difference is less than 0.04mg twice required, the determined requirements to meet a constant weight.
This requires a high degree of precision for the balance! Choose Ohaus EX balance to detect smog, quality is guaranteed! Â
2. Collect samples
The sampling environment and sampling frequency are in accordance with HJ/T194 .
When sampling, put the weighed filter into the filter net in the clean sampling clamp with the tweezers (the filter surface should face the intake direction), and firmly press the filter to the airtight.
After the sampling is finished, the dust surface will be folded twice; put into the sample box or paper bag, and the sampling record will be made.
The filter samples were weighed with a 0.01 mg analytical balance according to the method of treating the filter.
(If the filter is not weighed immediately after collection, the filter should be stored at 4 ° C in cold storage)
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3. Calculation of results
The calculation result retains 3 significant digits, and the number can be retained to the third digit after the decimal point.
4. Notes
The balance used in the experiment needs to have the following functions
· Readability needs to be 0.01mg
· Can eliminate the static electricity of fiber filter paper
When the PM2.5 content is very low, the sampling time should not be too short. When using an analytical balance, it is necessary to ensure that the particle loading on the filter is greater than 0.1 mg to reduce the weighing error.
Part Two
It can be seen that in the experiment of measuring the concentration of smog by gravimetric method, it is very important to choose a balance that is accurate, easy to use, safe to maintain and powerful.
Ohaus Explorer quasi-micro balance
Jiangsu Provincial Center for Disease Control and Prevention
PM2.5 special research project
Responsible for weighing before and after filter sampling
EX quasi-micro balance
Built-in static eliminator
Can eliminate static electricity on filter paper
Readability is 0.01mg
Linearity error ±0.1mg
With fully automatic calibration
Temperature difference of 1.5 ° C or 3 hours interval
The balance will automatically calibrate
Split modular design
Normal operation in a limited workspace
Part Three
After sharing the application of the scientific measurement smog method and EX balance in the environmental protection industry, Xiaoao took everyone to do a small calculation problem and calculated it:
How many smog in your lungs in the winter?
When a normal adult is in a calm state, the respiratory rate per minute is about 16 to 20 times, and the amount of breathing is 400 to 600 ml per time.
Suppose it is working in the ambient air for one hour a day (ambient air: refers to the outdoor air exposed by people, animals and buildings), so it takes 0.54m3 of smog air every day. In the standard state (standard pressure, 0 °C) , 1 m3 of air weighs about 1.29 kg.
How much smog does one have to smoke in a city that is exploding every day?
Calculated according to the PM2.5 burst value of 500,
500 μg/m3 x 0.54m3=270 μg
Assuming that the smog is in the worst hit area, there are 50 smog days in a winter.
Then an adult will have at least 13500 μg of smog in the lungs after a winter .
The individual cells in the human body weigh about 2~3n g. If a smog is the same as a single cell, how much smog will it accumulate in your respiratory tract?
According to calculation
So in a winter, an adult's respiratory tract may have a backlog of 5.4 million smog particles.
Assuming that these particles can enter the lungs, normal human lungs have about 300-400 million alveoli, which means there is a haze in every 500 alveoli.
It's no wonder that people who have never been sick can't stand up in the fog and cough.
Ohaus will continue to help the development of China's environmental protection industry and contribute to building a good ecological environment!
Small science
·PM2.5 particulate matter
Refers to particulate matter in the ambient air with an aerodynamic equivalent diameter of 2.5 microns or less, also known as fine particles.
·PM10 particulate matter
Refers to particulate matter in the ambient air with an aerodynamic equivalent diameter of 10 microns or less, also known as fine particles.
·PM0.3 particulate matter
Refers to the general term for solid particles or drops of aerodynamic equivalent diameter of 0.3 micron or less in ambient air, also known as lung particles. However, it has not been included in China's air environment testing system.
·Standard state
Refers to the state when the temperature is 273K and the pressure is 101.325kPa. The concentration of pollutants measured in China is the concentration under standard conditions.
references:
1. Determination of ambient air PM10 and PM2.5 by weight method HJ 618-2011
2. Ambient Air Quality Standard GB 3095-2012
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