Air quality is the overall description of air pollution levels in a defined area that may affect the environment and public health. Over the years, increasing levels of air pollutants from natural and human-related (anthropogenic) sources lead to poor air quality. According to the US EPA, an average adult inhales around 11,000 liters of air per day, while children breathe greater volumes of air, hence greater amounts of air pollutants which can lead to respiratory problems.