It seems that there are considerable air quality problems on our roads. The majority of our PM2.5 on roadways comes from wear on tires, brakes, and clutches, and these contain metals that have the ability to harm our lungs' immune response--particularly worrisome with the COVID-19 pandemic (Selley et al., 2020). Once airborne, these metal particles seem to be made more toxic as they are solubilized by acidic atmospheric sulfate (Fang et al., 2017). It seems that there are two options to be explored in terms of additions to road salt. One would be to add chelators to bind the metals on contact, and another would be to add pH adjustment to neutralize the acidity created by the airborne sulfate. Either one would need to be at low concentrations, since we know that chloride (and thus any other additions to road salt) is conveyed to receiving waters readily and disrupts their ecology (Ledford et al., 2016), but perhaps we could make significant reductions in pollution levels in winter time, even if we cannot supply an excess of chemicals to achieve high removals. This would mean that we would have to do a kinetics and fate & transport study to determine if an effective amount of the remediating substance could be added to do much good before it got washed into the receiving waters.
Idea No. 193