Step Three is to find the pollutants and identify them because this gives us a clue as to their source. Step Four is to eliminate our pollution sources. And the job is done. Pain is gone. An intriguing question will pop into your heads as you search your organs for parasites an pollutants.
Pollutants can jam their way into the cell's doorways too.
Both seem possible. Maybe both events go on simultaneously. Perhaps that is why bacteria and pollutants are always seen together. Viruses can land on your cell's doorways, too, and cause viral disease, but they are not as often pain producing. You will also notice something, as you keep testing and watching over your health.