{'fraction_non_alphanumeric': 0.02080624187256177, 'fraction_numerical': 0.0, 'mean_word_length': 5.015625, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
CLIMATE CHANGE AND AIR QUALITY

Air pollution is a major concern in the United States; it can threaten human health, damage ecosystems, cause haze and reduce well-being. At the same time, the Earth's climate system has the potential to both affect, and be affected by, air pollution. The first section of this paper is intended to provide background on the current status and trends of air pollutant emissions and concentrations, with a focus on mobile sources. The next section briefly describes historical and ongoing programs to reduce mobile source emissions. The third section discusses the potential interactions between climate, climate change and air quality. The last section details a few key research needs to further our understanding of these interactions.