About unit of monthly report

When representing nitrogen dioxide (NO2) and sulfur dioxide (SO2) data, ppm is generally used as a unit, but in the monthly report, a unit called ppb is used to make the number of tables easier to read. Similarly, different units are used for suspended particulate matter (SPM), etc.
This page describes the relationship between commonly used units and the units used in the monthly report.

The monthly report on page 1 contains up to 744 data (31 days x 24 hours), but if there are a large number of zero data such as 0.001 ppm, it is the same five-character numerical value. There is a drawback that it is difficult to understand the size of the data just at first glance.
For this reason, when creating (printing) a monthly report, it is necessary to make it easier to grasp the size of the numerical value in a large number of data.
For items displayed up to one decimal point (e.g., CO, etc.), the number is multiplied by 10 times, 100 times for two digits (such as NMHC), and 1000 times for 3 digits (such as NO2), and 1000 times for 3 digits (such as NO2) to eliminate the decimal point.
By integers in this way, it is easier to grasp the size of the numerical value by looking at the number of digits (number of characters) of the data.
As a result, the unit will also be used as a unit for monthly report.

For example, the unit of nitrogen dioxide (NO2) generally uses ppm (1/million), and is displayed in five characters including the decimal point (three decimal place) such as 0.123 ppm.
On the other hand, in the case of monthly reports, in order to make the table easier to read and to print the monthly report on one page, shorten the string displaying the numerical value, and put it in the paper width (for example, B4). Instead of ppm, ppb (1 billionth), which is a unit obtained by multiplying the value of ppm by 1000 times.
For example, in the case of NO2, if 0.001 ppm is converted into 1ppb, it is 0.001 ppm. → １ppb、０．０１２ppm → １２ppb、０．１２３ppm → 123ppb, the size of the numerical value is reflected in the number of digits, making it easier to grasp the size of the numerical value.
In addition, since the number of characters displayed in the data decreases from 5 to 3 characters, the monthly report can be laid out so that it fits within the width of the paper.