Scientifically speaking, any link between a decrease in ozone and an increase in melanoma cancers is in some degree speculative.
But realistically speaking, it's better to be safe than sorry. The bottom line is that the protective layer of Earth's atmosphere is decreasing due to man-made waste and pollutants. The less protection that we receive from the ozone layer, the more likely we are to see the effects of this in our hospitals and on our skin.
Cases of melanoma are becoming more and more frequent, and it would appear not to be purely coincidental that the ozone layer depletes in an inverse proportion to the cancer rates observed by our nation's physicians.
So too must our own precautions against melanoma increase in numbers inversely proportional to ozone levels. That means wearing sunglasses whenever we venture outside.
Wear protective hats and sunproof clothing, and make sure our children do the same.
Apply sunscreen of SPF 15 or greater, everyday! This doesn't change depending on the weather reports. Sunshine or cloud, apply that sunscreen religiously.
And lastly, avoid spending more time in the sun than absolutely necessary. Don't go tanning. Consider supplementing your diet with vitamin D, at your doctor's counsel and discretion.
Melanoma cancers don't have to increase in frequency as the ozone levels decline, so long as our knowledge about the dangers of sun exposure increases in inverse proportion.