6月下半月，全国大部分地区空气质量以优良为主

Core Viewpoint - The overall air quality in China for the second half of June is expected to be predominantly good, with some regions experiencing moderate pollution due to high temperatures and dust storms [1][2]. Group 1: National Air Quality Forecast - The air diffusion and wet removal conditions across the country are generally favorable, leading to good air quality in most areas [1]. - The Beijing-Tianjin-Hebei region and surrounding areas may experience light to moderate pollution due to high temperatures, particularly from June 17 to 30 [1]. - Dust storms may cause moderate or higher pollution levels in eastern and southern Xinjiang during certain periods [1]. Group 2: Beijing Air Quality Forecast - In Beijing, the air quality is expected to be good for most of the second half of June, with some periods of light ozone pollution [2]. - From June 18 to 25, average diffusion conditions are expected, leading to light pollution from ozone [2]. - The primary pollutant in Beijing during this period is expected to be ozone (O3) [2].