When we express data of nitrogen dioxide (NO2) and sulphur dioxide (SO2), ppm is used as unit generally, but uses unit called ppb to make it easy to read number list in monthly report. In addition, even suspended particulate matter (SPM) uses another unit equally.
In this page, we explain relations with unit used in unit and monthly report used generally.
Up to 744 (31st X 24 hours) data are listed in monthly report on page 1, but there is difficult point that big things and small things of data are incomprehensible when a lot of data which zero follows like 0.001 ppm line up because it is number of same five characters only by having had a look.
Therefore, it is necessary to be easy to grasp numerical big things and small things in data forming a line a lot when it has making (print) of monthly report.
General losing decimal by (NO2) doing number 1,000 times in the case of 100 times, three digits in the case of 10 times, two digits in (NMHC) in (CO) in the case of item to display to decimal one digit, and treating for integer.
It becomes easy to keep numerical big things and small things under control by seeing the number of the figures of data (the number of the letters) when we become integer in this way.
With this, unit uses unit for monthly report, too.
For example, generally ppm (one per 1 million) is used, and unit of nitrogen dioxide (NO2) is displayed like 0.123 ppm in five characters (decimal three digits) including decimal point.
On the other hand, we use ppb (one per 1 billion) which is unit that did number of ppm 1,000 times not unit of ppm including decimal point to shorten character string to display number to print monthly report on 1 page when it is easy to look at the face and does in the case of monthly report, and to put in yokamifuku (for example, horizontal B4).
For example, when, in the case of NO2, credit converts 0.001 ppm into 1ppb, 0.001 ppm → 1ppb, 0.012 ppm → 12ppb, 0.123 ppm → As 123ppb and numerical size are reflected to the number of the figures, it becomes easy to keep numerical big things and small things under control.
In addition, we can lay out monthly report because the number of the indication letters of data decreases below three characters from five characters to occupy width of paper.
Relations with general unit and unit of monthly report
|Measurement item||With general unit|
|Unit of monthly report||Relational expression (unit conversion) of both||Indication example of both|
|Sulphur dioxide (SO2)||ppm||Three digits||ppb||1 ppm = 1000ppb|
= 1,000*0.001 ppm
|0.123 ppm → 123ppb|
|Nitric oxide (NO)|
|Nitrogen dioxide (NO2)|
|Nitrogen oxide (NOx)|
|Photochemical oxidant (OX)|
|Carbon monoxide (CO)||ppm||One digit||*0.1 ppm||1 ppm = 10*0.1 ppm||1.2 ppm → 12*0.1 ppm|
|Non-methane hydrocarbon (NMHC)||ppmC||Two digits||X 0.01ppmC||1ppmC = 100 X 0.01ppmc||2.34ppmC → 234 X 0.01ppmC|
|All hydrocarbons (THC)|
|Suspended particulate matter (SPM)||mg/m3||Three digits||μg/m3||1 mg/m3 = 1,000 μg/m3|
= 1,000*0.001 mg/m3
|0.123 mg/m3 → 123 μg/m3|
|Microparticulate matter (PM2.5)||µg/m3||None||μg/m3|| || |
|The wind velocity||m/s||One digit||*0.1m/s||1m/s = 10*0.1m/s||1.2m/s → 12*0.1m/s|
|The direction of the wind||16 directions||－||16 directions|| || |
|Temperature||℃||One digit||*0.1 degree Celsius||1 degree Celsius = 10*0.1 degree Celsius||23.4 degrees Celsius → 234*0.1 degree Celsius|
|Humidity||％||None||％|| || |
|Quantity of sunlight||MJ/m2hr||Two digits||X 0.01MJ/m2hr||1MJ/m2hr = 100 X 0.01mj/m2hr||1.23MJ/m2hr → 123 X 0.01MJ/m2hr|
|Quantity of emission income and expenditure|