[JimD]

Here's some of the wikipedia article on diesel exhaust:

"Diesel combustion exhaust is a major source of atmospheric soot and fine particles, which is a fraction of air pollution implicated in human cancer,[5][6] heart and lung damage,[7] and mental functioning.[8] Diesel exhaust also contains nanoparticles, which have additional health impacts, and are as yet poorly understood.[citation needed]

[edit] ParticulatesDiesel particulate matter (DPM), sometimes also called diesel exhaust particles (DEP), is the particulate component of diesel exhaust, which includes diesel soot and aerosols such as ash particulates, metallic abrasion particles, sulfates, and silicates. When released into the atmosphere, DPM can take the form of individual particles or chain aggregates, with most in the invisible sub-micrometre range of 100 nanometers, also known as ultrafine particles (UFP) or PM0.1.

The main particulate fraction of diesel exhaust consists of fine particles. Because of their small size, inhaled particles may easily penetrate deep into the lungs. The rough surfaces of these particles makes it easy for them to bind with other toxins in the environment, thus increasing the hazards of particle inhalation.

[edit] Health effectsExposures have been linked with acute short-term symptoms such as headache, dizziness, light-headedness, nausea, coughing, difficult or labored breathing, tightness of chest, and irritation of the eyes and nose and throat[citation needed]. Long-term exposures can lead to chronic, more serious health problems such as cardiovascular disease, cardiopulmonary disease, and lung cancer.[5][6] Ambient traffic-related air pollution was associated with decreased cognitive function in older men.[8]"

The big difference between gas and diesel engines seems to be the fine particles produced by the diesel. It seems like the ugly appearance of the black clouds coming out of diesels is a good warning to avoid the vicinity. The particulate matter in that exhaust is not just unattractive it is unhealthy (but no vehicle exhaust is something I want to deliberately breath).

If BMW brings the turbo diesel version of the X1 over it may be my next purchase, however. I am not a diesel hater. But I don't like it when I see a plume of exhaust from a diesel headed my way.

Jim