The main sources of aerosols are natural events like volcanoes, sea spray, forest fires, and soil erosion. But some aerosols are also produced by human activity, like combustion of fossil fuel. Particles smaller than 2.5 mm are a serious concern for both visibility and human health. Aerosols absorb and reflect light, producing the haze in cities. They can also be breathed in and stay in the respiratory system causing respiratory illness and even cancer.
Aerosols also have an important effect on global climate.
They also reflect solar radiation, thereby cooling the earth. The amount of aerosols produced by Canadian agriculture has not been measured routinely but is probably small. The most common aerosol from Canadian farms is probably dust from soil erosion. When soil is dry, loose, and without plant cover, the wind can pick up surface particles and carry them great distances. The problem was most severe in the southern prairies during the dirty thirties, when as much as several centimetres were lost from some fields, obscuring the sky and depositing dust everywhere.