I recently saw Associate Editor Jessica Stoikes's article "Asbestos in Asphalt?" from the February 2015 issue of Asphalt Contractor.
The article provides a good overview on how DOTs and contractors need to handle an extremely rare situation; however, the headline, deck, and image of a man in a HazMat suit could be quite alarming to an uninformed audience.
According to Mundt et al. (2009), only eight states reported having used asbestos in hot mix asphalt and none did so regularly. "No state reported current or historical use of asbestos in HMA for mainline road paving, although eight states (Florida, Indiana, Iowa, Minnesota, New York, Ohio, Pennsylvania, and Washington) reported infrequent low-volume use, with earliest and most recent use dates reported as the 1940s and the 1970s, respectively." The same paper notes some additional testing and use of asbestos fibers in asphalt in those and a few other states, but it was far from a universal practice. [Mundt, D.J.; K.M. Marano; A.P. Nunes; & R.C. Adams (2009). A Review of Changes in Composition of Hot-Mix Asphalt in the United States. Journal of Occupational and Environmental Hygiene, Vol. 6, No. 11, pp. 714-725. DOI:10.1080/15459620903249125]
Ideally, the DOTs in each of those states have a good idea of the rare instances when and where asbestos fibers may have been used and it can, as PennDOT did here, put in place precautions to make sure workers and the public are kept safe. Absent DOT acknowledgment or identification, if a company has a reasonable suspicion (based on the location of a job, the pavement structure type, or the date the original pavement layer was placed) that they might encounter asbestos during milling, core samples could be taken, analyzed, and then appropriate safety measures could be implemented in the very rare case asbestos is actually present.
As the article noted, only 55 miles of Pennsylvania roads contain asbestos out of more than 100,000 miles of asphalt surfaced roads; that's less than 0.055% of Pennsylvania's roads. Generally, these pavements were experimental, may have predominantly included bridgework, and appear to have been documented by the DOT. According the Pennsylvania Asphalt Pavement Association, the typical process is to only overlay (and not mill) a pavement layer known to include asbestos.
Clearly this is an extremely unusual situation and one that only affects a small number of older pavements. Our worry is that someone might get the idea from the article that this is a common problem and that it could raise unnecessary concerns about asphalt pavements among the public or others.
T. Carter Ross, Vice President for Communications
National Asphalt Pavement Association