Yes - prolonged sun exposure can damage the eKO Series. Since the rubber used for the eKO Series is all natural and eco-friendly, it will break down and oxidize over time and with use and exposure to direct sunlight speeds up this process. Once the mat has started to oxidize and dry out, it is not possible to bring it back to its original grippy condition. To maintain the performance of the eKO Series use Manduka's Natural Rubber Yoga Mat Restore.