Don't inhale
Keep on Breathin'

by Carolyn Chase


iesel engines power most of the nation's trucks, buses, trains, ships and off-road machinery. When Rudolph Diesel invented the his engine in 1893, pollution was not on his mind. A century later, diesel pollution is a dirty reality in our airspace.

One of the world's most efficient engines, over the years improvements have been made to their exhaust emissions. But diesel engine exhaust is still a health hazard.

The California Air Resources Board voted last week to take the political step to formally list the particulate matter found in diesel fuel exhaust as a "Toxic Air Contaminant." A panel of leading scientific experts spent nine years reviewing the evidence on diesel exhaust and were unanimous in their conclusions of the public health risk. This listing will lead to actions to finally develop a prudent plan to reduce human exposure.

Diesel has been determined to be a potential human carcinogen. More than 30 studies reviewed by CARB demonstrated a 40% increase in the risk of lung cancer after worker exposure to diesel exhaust. These studies included truck drivers, bus mechanics, equipment workers, dock workers, railroad workers, highway workers and wood workers. The clear and consistent conclusion of the scientific bodies that have studied diesel exhaust is that it presents a serious threat to public health.

Asthma symptoms were linked to truck exhaust. A school's proximity to freeways was linked to asthma prevalence. The proximity of a child's residence to major roads is linked to hospital admissions for asthma. Living near truck traffic can reduce lung function in children.

In a preliminary finding, the EPA found that exposure to diesel exhaust, even at low levels, is likely to pose a risk of lung cancer and other respiratory risk. The EPA stated that the risk of cancer from diesel exhaust, even at concentrations too low to cause other respiratory problems could be 1 in 100, or even greater.

Geez. That would include someone you know personally.

According to data from the National Center for Health Statistics, 8,147 adults died from cardiopulmonary causes in the San Diego metropolitan area in 1989. A Natural Resources Defense Council report estimates that particulate air pollution plays a role in about 1,000 of these deaths. CARB reports that 14,000 Californians will be stricken with cancer solely from their exposure to diesel exhaust.

While only between 2-3 percent of all California vehicles use diesel engines, their exhaust constitutes 60 percent of all the particulate pollution and 30 percent of nitrous oxides - another harmful component of smog.

Mobile sources generate the majority of diesel exhaust pollution. Heavy-duty trucks, urban buses, passenger cars and light-duty trucks, trains, ships, boats and other mobile applications all contribute to the problem, emitting up to 27,000 tons of diesel exhaust particulates in California in 1995.

The good news is that the emission exhaust from mobile sources in California is expected to decrease through 2010 because of emission standards and regulations already adopted by the Air Resources Board and the U.S. EPA. Because of improved federal standards, diesel engines are 90% cleaner than they were ten years ago.

The problem is that by 2010, if no additional standards or regulations are adopted and in light of blossoming population and more cars on the roadways, the emissions are expected to increase. CARB finally acknowledging the scientific reality paves the way for needed standards.

CARB is clearly concerned with what it calls PM10, a measurement of particulate matter 1/l0th to 1/50th the width of a human hair. Particulate air pollution is not just visible smoke and soot; it is also made up of tiny invisible particles formed from gaseous emissions of sulfur dioxide and volatile organic compounds. These tiny particles are considered to be the most dangerous by health scientists because they are small enough to evade the body's respiratory defense mechanisms and lodge deep in lung tissue. Almost all of diesel particle emissions are in this range. Previously, standards did not target fine particle pollution.

When you breathe in anything containing particulate matter, your lungs suffer. Because of their small size, these particles can be inhaled and a portion will eventually become trapped within the small airways of the your lungs. This increases the potential that you'll get sick or find respiratory illnesses like asthma, emphysema or bronchitis, getting worse.

One problem CARB's action does not address is pollutants from trucks burning dirtier out-of-state diesel fuel. Currently, more than 50% of the miles driven by large trucks in California are driven by truck coming in from other regions. Clean diesel fuel burned in cleaner diesel engines has 90% fewer particulate emissions and more than 70% fewer other smog causing gases than diesel used in California just 12 years ago. But clean diesel fuel is only currently available for retail purchase in California and Sweden.

So what's next? It has to make me smile to receive the following quote from the California Trucking Association: "It's time for every truck on the road to be smokeless, whether it's based in California or not. We have the technology and we have the fuel. And now, with this decision by the Air Resources Road, we have the direction we need to make diesel fuel safer and cleaner for the future - and that's good for everyone."

Clean Air Partners Inc., a designer, manufacturer and marketer of conversion systems in San Diego, converts all engines - gasoline and diesel - to run on natural gas or run on a bi-fuel system, with natural gas being half of the fuel source.

If all engines ran on readily available natural gas fuel, the company's literature points out, the United States could reduce fuel cost by $60 billion annually, reduce automotive pollution by 80 percent, eliminate dependence on $50 billion of imported oil every year, and create four million new jobs. Hawthorne Power System in San Diego, which sells tractors and engines, provides natural gas engine conversions at its Kearny Mesa division.

The translation of a governmental regulation into direction and leadership is an amazing thing. So let's get those clean diesels on to the roads and keep on truckin' and breathin'.