In this study we compared a "baseline" condition of uncontrolled diesel engine exhaust (DEE) emissions generated with current (circa 2003) certification fuel to an emissions-reduction (ER) case with low sulfur fuel and a catalyzed particle trap. Lung toxicity assessments (resistance to respiratory viral infection, lung inflammation, and oxidative stress) were performed on mice (C57Bl/6) exposed by inhalation (6 hr/day for 7 days). The engine was operated identically (same engine load) in both cases, and the inhalation exposures were conducted at the same exhaust dilution rate. For baseline DEE, this dilution resulted in a particle mass (PM) concentration of approximately 200 µg/m
3 PM, whereas the ER reduced the PM and almost every other measured constituent [except nitrogen oxides (NO
x)] to near background levels in the exposure atmospheres. These measurements included PM, PM size distribution, PM composition (carbon, ions, elements), NO
x, carbon monoxide, speciated/total volatile hydrocarbons, and several classes of semivolatile organic compounds. After exposure concluded, one group of mice was immediately sacrificed and assessed for inflammation and oxidative stress in lung homogenate. Another group of mice were intratracheally instilled with respiratory syncytial virus (RSV), and RSV lung clearance and inflammation was assessed 4 days later. Baseline DEE produced statistically significant biological effects for all measured parameters. The use of low sulfur fuel and a catalyzed trap either completely or nearly eliminated the effects.
Key words: diesel exhaust, emissions reduction, health effects, metals, organic carbon, particulate matter health effects.
Environ Health Perspect 112:1307-1312 (2004). [Online 7 July 2004]
Address correspondence to J.D. McDonald, Lovelace Respiratory Research Institute, 2425 Ridgecrest Dr. SE, Albuquerque, NM 87108 USA. Telephone: (505) 348-9455. Fax: (505) 348-4980. E-mail: jmcdonal@lrri.org
This study was supported by the Department of Energy Office of FreedomCAR and Vehicle Technologies. Partial support was received from the National Institute of Environmental Health Sciences through grant P30 ES-012072 to the New Mexico Center for Environmental Health Sciences.
This article does not represent the views and opinions of any federal sponsor.
The authors declare they have no competing financial interests.
Received 1 March 2004; accepted 7 July 2004.
