Is Road Surface Asphalt Posing Health Risk to Nigerians?

Hot mix asphalt, used mainly for road construction, is produced by mixing aggregates -- gravel, crushed stones, rock dust or powder - with bitumen under high-temperature conditions. This is done using an assembly of mechanical equipment in a plant - a facility which may be a temporary or permanent structure. These asphalt production plants are sometimes located within residential areas for convenience and proximity to construction sites. 

Emissions from hot mix asphalt and other plant operations, such as heating of aggregates and bitumen, loading and transportation of materials, as well as vehicle and facility maintenance, introduce various contaminants, like heavy metals, into the environment. The demand for road construction and highway expansion in Nigeria has led to an increase in the number of asphalt production plants in the country. Aggregates used for asphalt production have varying concentrations of heavy metals. Some of these metals may escape from the aggregates and bitumen during asphalt production into the surrounding soil and water sources, writes Ifenna Ilechukwu for The Conversation.