In “Cool idea” (SN: 10/5/13, p. 26), Erin Wayman explored the potential climate benefits of cutting back on emissions of black carbon, a component of soot, and other lesser-known climate warmers.
Reader Ellis Johnson e-mailed that U.S. EPA regulations have greatly reduced particulate matter emissions from diesel vehicles in recent years. “When was the last time you saw black smoke coming from a highway truck?” he asks. Wayman responds: “The United States has made great strides in reducing pollution from diesel vehicles, but in many parts of the world, diesel trucks and cars are still a major source of black carbon.”
A related climate-changing problem is pointed out by reader Natasha Aristov. “I can imagine that some powerful people will, instead of implementing climate-warming prevention measures at home, point their