The history of air pollution has become an increasingly important topic in recent years. Air pollution is the result of major industrial and technological advances throughout the last century, as well as increasing levels of emissions from car traffic and other sources. The release of pollutants such as carbon dioxide, nitrogen oxides, sulfur dioxide, and particulate matter (PM) into the environment can cause burning of the eyes, noses and throats, coughing, and can even lead to more serious health problems in vulnerable populations. In the United States, the passage of the Clean Air Act in 1963 provided a major milestone in air pollution policies. The Act required the Environmental Protection Agency to develop regulations to reduce air pollution, which led to the establishment of the National Ambient Air Quality Standards (NAAQS). The NAAQS set limits for allowable levels of emissions of six criteria pollutants, including particulate matter, ozone, lead, sulfur dioxide, carbon monoxide, and nitrogen oxides. These standards have been regularly updated and continue to evolve as new data, technology, and information become available. In recent years, cities and other governments around the world have recognized the serious problem of air pollution and have taken action. In some countries, programs have been established to reduce vehicle emissions through fuel-efficient designs and cleaner burning fuel. In addition, the burning of coal has been reduced, and manufacturers have been required to meet stricter emissions regulations. Some cities have also implemented stricter public transportation and walking/cycling policies to reduce car use and traffic-related air pollution. Despite these efforts, there is still much work that needs to be done to address the air pollution issue. For example, many countries still have coal power plants and vehicle fleets that need to be upgraded to meet stricter standards. In addition, air pollution emissions from industries and agricultural activities remain problematic and require further regulation. Solutions to reduce air pollution must be pursued on multiple levels, including technological and policy-based approaches, in order to achieve positive change.