Diesel exhaust is considered a probable carcinogen (International Agency for Research on Cancer). It has also been linked to asthma and increase sensitivity to allergens.
Asphalt fume can cause irritation of the skin and the upper respiratory tract (eye, nose, and throat) and has been associated with wheezing and shortness of breath. Based on current knowledge, it is uncertain if asphalt exposure increases the risk of cancer for workers engaged in asphalt paving.
Ultrafine air particles (very small particles in the air) such as those that make up diesel exhaust have been linked to respiratory irritation and decreased lung function.
Exposure can be reduced by the use of controls such as the agreement on the use of exhaust ventilation on highway class pacing machines, or milling machines with exhaust ventilation. Other controls such as using low temperature asphalt, better work practices, proper placement of engine exhaust stacks and respiratory protection can help reduce worker exposure.