The word immune, as used in the passage, most nearly means ____.
Too much exposure to the sun can damage not only your skin, but also other parts of your body. Everyone is exposed to some sunlight during daily activities. Being in the sun too much can burn the skin and cause skin cancer and premature aging. Many people do not know, however, that overexposure to the sun can also contribute to cataract formation, allergies, and immune system damage. Young people are the most at risk since 50% of one’s sun exposure is accomplished by age 18. Older folks also need to be careful and monitor their sun exposure.