Is it true that on/in the earth there are the same amount of elements/gases at any given time?

Question

but are just distributed for the worse by having cars and trucks and polution

Answer 1

Very true! The problem is simply one of the form in which these gases/ elements are present, The chemical compositions or compounds that may contain these elements/ gases can be created, for good or bad, by us, or even by nature.

These unfortunately include those created by our cars and trucks, and lots more activities.

Answer 2

That's basically true, because matter can neither be created nor destroyed, right?

However, when we mine coal or pump up oil and burn it, we are taking something that has been locked away for tens of millions of years, and letting it go.  That is, the CO2 that was stored in the animal shells / plant matter that formed the coal and oil.

So it's a cop-out to say that we aren't changing anything.  We actually are.

In case that was the point of your question.