A: i want to change the thickness of the smog but i don't understand the settings
Q: the threshold for each level of thickness is decided by the following exponential function: (a*b^x+o)

if you don't know what that means don't worry. I'll visualize it for you to understand.

this is what that function looks like on a graph

you can make your own exponential function on https://www.desmos.com/calculator
with equation i provided. y = (a*b^x+o).

the default values for the parameters of this equation are
a = 30 <- this is the y-intercept
changing this value will move the curve left or right.

b = 2.5 <- this is the base.
changing this value will increase or decrease the bendiness of the curve.

o = 0 <- this is the x offset
changing this value will move the curve up or down

Q: what does pollution level mean?
A: its how badly a chunk is polluted.
if you want to know the values of a polluted chunk you can look for an option called "show-pollution-values". if you check this option and look at the map,
you can see the pollution level for each chunk.

based on this you can decide at what pollution level you want a certain thickness.

i know this is a cumbersome process but i was unable to make this any easier. I'm very sorry :(