Fact Sheet
Locomotive Operations and Air Pollution in
Southern California

February 2006

Overview
Locomotives and rail yard operations are a significant source of smog-forming and toxic emissions and controlling these emissions is crucial to cleaning up Southern California smog.  Diesel locomotives in the region emit about 33 tons per day of smog-forming nitrogen oxides.  That is more than the combined emissions from the area’s 350 largest facilities, including all of the oil refineries, power plants and major manufacturing plants.

Which Railroads Operate in Southern California?
Currently there are four railroads operating in the region.  Union Pacific Railroad Co. (UP) and BNSF Railway Co. (BNSF) have long-haul railroad operations, and Los Angeles Junction Railway (LAJ), owned by BNSF, and Pacific Harbor Line, Inc. (PHL) have switching and terminal rail operations.  CARB estimates that combined BNSF and UP operate approximately 240 locomotives that are dedicated to the region, while LAJ and PHL operate approximately 25 locomotives in the area.  AQMD has estimated that there are an additional 1,900 locomotives that periodically operate in the region, but are not part of the intradistrict or those locomotives that are dedicated to the region.

How much do trains pollute?
Diesel exhaust is a complex mixture of gases and fine particles.  It is emitted by diesel-fueled internal combustion engines and contains many carcinogenic compounds.  In 1998, CARB identified diesel exhaust as a toxic air contaminant based on its cancer causing potential. 

AQMD’s 2003 Air Quality Management Plan estimates that locomotives emit about 33 tons per day of nitrogen oxide (NOx) emissions and about 1 ton per day of particulate matter (PM10).  Locomotives also emit volatile organic compound emissions which along with NOx are primary contributors to ozone formation. 

How many rail yards are there in Southern California?
There are currently 19 major rail yards operated by the four railroads in the region in the following locations.

What are the health risks from locomotive diesel emissions?
In October 2004, CARB conducted a health risk assessment to estimate the cancer risk from diesel exhaust from locomotives at the Union Pacific J.R. Davis Yard in Roseville. The results of this analysis showed that the maximum average off-site diesel PM cancer risks from the facility ranged from 900 to 1,000 in 1 million.  In comparison, the AQMD's Rule 1402 limits the cancer risk from existing facilities to less than 25 in a million, moreover oil refineries and power plants pose a maximum cancer risk of less than 10 in 1 million.

The health risk assessment conducted at the J.R. Davis Yard was the first of its kind by any air quality agency in California. As a result, the cancer risks from rail yards in Southern California are not known. Based on the size of rail yards and their proximity to residents, the risks at rail yards in the Basin may well be significant. 

AQMD adopted Rule 3503 -- Emissions Inventory and Health Risk Assessment for Rail Yards -- to develop emissions inventories and health risk assessments at freight rail yards in the region, and to notify the public if the risks from rail yards are above a specified threshold.

What about passenger trains?
Passenger railroads operating in the region, such as Amtrak and Metrolink, contribute less than 10 percent of the NOx and PM emissions from railroad operations in the region.  Passenger railroad operations conduct very little switching and cargo handling activities.  Passenger rail yards are currently exempt from AQMD's railroad rules.  If warranted, passenger operations may be considered in the future.

AQMD is the air pollution control agency for Orange County and major portions of Los Angeles, San Bernardino and Riverside counties.

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