Measures taken by the Greek authorities throughout the 1990s have improved the quality of air over the Attica Basin. Nevertheless, air pollution still remains an issue for Athens, particularly during the hottest summer days. In late June 2007, the Attica region experienced a number of brush fires, including a blaze that burned a significant portion of a large forested national park in Mount Parnitha, considered critical to maintaining a better air quality in Athens all year round. Damage to the park has led to worries over a stalling in the improvement of air quality in the city.