Fugitive dust originates in small quantities over large areas. Significant sources include unpaved roads, agricultural cropland and construction sites. Recent research indicates that there are significant health considerations involved as well. Unpaved roads produce about 10 million tons of particulate matter air pollution each year in the United States. A small amount of fugitive dust occurs naturally.
Wind erosion occurs continuously, especially in arid, open areas with sparse vegetation.
Human activity coupled with unfavorable weather conditions can dramatically increase fugitive dust levels. Heavy tillage of marginally productive land combined with the extended drought to create a fugitive dust problem of huge magnitude. In more recent years, improved agricultural practices and increased paving of rural roads have resulted in a decrease in the total amount of fugitive dust. Accurate measures before 1985 are not available. By 1990, this level had decreased to about 25 million tons and remained near that level through 1997.