The phrase "damage increases" means that the amount of harm or destruction caused by something goes up or gets bigger.
Sentences with «damage increases»
Researchers find that a substance indicating oxidative damage increases in urine as people get older. (sciencedaily.com)
So it sounds like it's possible, but only to be done in dire circumstances with the likelihood of damage increasing with distance travelled. (mechanics.stackexchange.com)
In the corn snakes, oxidative damage increased by almost 180 % during digestion. (sciencedaily.com)