Kailash Kumar
SENIOR MEMBER
- Oct 8, 2018
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@PakSword
One possible explanation is the measurement of air particles they reviewed in this report.
Air particles can be measured in PM 10 which means particles with a diameter smaller than 10 µm and in PM 2.5 which means air particles with a diameter smaller than 2.5 µm. There is also PM 1 and PM 0.1.
This report reviewed air particles of PM 2.5.
When you look at PM 2.5, Karachi scores 69 µm/m^3 (see the website) which is moderate on the scale described above.
I did find other data from a different organisation, the WHO, which has reviewed PM 10 and PM 2.5 µm.
Air pollution data from World Health Organization
PM 10: 290 µm/m^3
PM 2.5: 88 µm/m^3
PM 10 Pollution Level: Extremely High
With this data you can see that the measurements obtained by the WHO of PM 2.5 result in a value of 88 µm/m^3 which is in the same region of 69 µm/m^3.
But when you look at PM 10 it is 290 µm/m^3, which according to the WHO is Extremely High.
In other words, Karachi has moderate pollution of smaller air particles (which is why it is ranked lower) and extremely high pollution of larger air particles.
If PM 10 was reviewed, Karachi would have ranked a lot higher.
They chose in this report to review data of measurements of smaller air particles since they have a larger effect on the health of a person.
From the report:
