Letters | Catalyst Spring 2012
Forecasting Ozone Pollution
Your recent article in Catalyst on global warming [“Climate Change May Be Hazardous to Your Health,” Fall 2011] is incomplete. Temperature is only one of several variables in ozone formation. One of the most critical is local weather.
Most high pollution occurs when air is trapped in the lower part of the atmosphere (the “mixed layer”). We cannot predict changes in local meteorology due to global warming. The concentration of pollutants can get better or worse depending on the amount of change in the intensity and duration of small mixed layers.
The author responds:
We recognize that ozone formation depends on a number of climatic factors, and agree that coupling climate and local air quality modeling is the most comprehensive approach to evaluating ozone concentrations in the atmosphere. We were unable to get into detail on all these factors in the Catalyst article, but we do address some of them in our report Climate Change and Your Health: Rising Temperatures, Worsening Ozone Pollution.
Liz Perera, senior Washington representative
UCS Climate and Energy Program
Hybrid Technology for Non-Hybrids?
One of the most sensible and efficient qualities of a hybrid is that its gas engine shuts off when the car is stopped, as is so often the case with stop-and-go driving. . . . The ability to stop the engine as often as [possible] would seem, by itself, able to noticeably reduce fuel usage, emissions, engine wear, and so on.
Would adding the automatic shutdown ability to a regular car be possible, and if so, would it be a good thing to do as well? I also wonder if such a system for a regular car could include regenerative braking (to help recharge the battery and reduce brake pad/shoe wear).
William H. Clarke
“Stop-start” (also known as “micro hybrid” or “idle-off”) technology, which shuts off a conventional gasoline engine when idle, is not available as a retrofit for existing cars and trucks. However, this feature is available on some models in Europe and we will soon see it in the United States as well, thanks to new vehicle standards that call for lower global warming emissions and improved fuel economy. Stop-start technology adds between $100 and $400 to a vehicle’s purchase price, but quickly pays for itself by cutting fuel consumption around 5 percent.
Regenerative braking, which is available on “mild” and “full” hybrid vehicles, requires a higher-voltage battery and more sophisticated electronic controls. See “How It Works” to learn more about advanced vehicle technologies.
Jim Kliesch, research director
UCS Clean Vehicles Program