Digging Up Trouble

The Health Risks of Construction Pollution in California

Published Jul 15, 2006


Pollution from diesel construction equipment is taking a heavy toll on the health and economic well-being of California residents. This equipment contributes to particulate and ozone pollution that can cause severe cardiovascular and respiratory illnesses, asthma attacks, acute bronchitis, and even premature death. Lagging emission standards and very old equipment have made construction equipment one of the largest sources of toxic diesel particulate matter pollution in the state, necessitating an accelerated cleanup program to protect the health of all Californians.

Using established U.S. Environmental Protection Agency and California Air Resources Board methods to quantify the impact of air pollution, the Union of Concerned Scientists estimates that construction equipment emissions statewide are responsible for the following impacts on our health and economy:

 Health Endpoint

Mean Annual Incidences

Annual Costs (in thousands of 2005 dollars)

Premature Deaths



Respiratory Hospitalizations



Cardiovascular Hospitalizations



Asthma and Other Lower Respiratory Symptoms



Acute Bronchitis



Lost Work Days



Minor Restricted Activity Days



School Absences



Total Annual Cost  


The impact of construction pollution on public health is greatest where equipment and people mix, and 90 percent of the health and economic damage occurs in California’s five most populous air basins:

  • The South Coast air basin (which encompasses most of Los Angeles, Orange, Riverside, and San Bernardino counties) ranks first, with more than 700 premature deaths and more than 1,000 hospitalizations for respiratory and cardiovascular illness annually.
  • The San Francisco Bay Area and San Diego follow, with more than 150 and 89 premature deaths, respectively, every year.
  • The San Joaquin Valley and Sacramento Valley (the two largest air basins in California’s Central Valley) round out the top five, with 49 and 39 annual premature deaths, respectively.  

While incentive programs have begun to clean up some of this equipment, only statewide regulations can achieve the reductions in construction equipment pollution needed to truly protect public health. Cost-effective technology solutions that would help meet this regulatory goal already exist, and more will become available over the next few years. In July 2007, CARB adopted a regulation that will require existing construction equipment to be cleaned up by retiring the oldest, most-polluting equipment and/or using retrofit technology.

What types of health and economic damage are caused by construction equipment pollution in California?

Construction equipment is one of the largest sources of diesel soot and smog-forming nitrogen oxides in California. It is responsible for an estimated 1,100 premature deaths across the state every year and more than 1,000 hospitalizations for heart and lung disease. Asthma attacks number in the tens of thousands, while days when activity is restricted number over one million. Worker productivity and children’s education are also affected, with an estimated 180,000 lost days of work and more than 300,000 days of school absences. The health costs of construction-related diesel emissions are estimated at $9 billion per year—a bill footed by everyone in California.

Why is construction equipment so dirty?

The combination of lagging emission standards and long operational life has made construction equipment one of the largest sources of diesel particulate matter in the state. Construction and other off-road equipment did not face new particulate matter (PM) emission standards until 1996, with some engines unregulated as late as 2003. New engine standards will phase in over a seven-year period starting in 2008, but the long life of the equipment will prevent the benefits of these new standards from being fully realized until after 2030. Excavators represent the category of construction equipment that emits the most annual emissions of toxic diesel PM in California. The average excavator emits as much particulate matter in one hour as a new "big rig" traveling 1,100 miles.

What does the mapping of Construction Risk Zones conducted for Digging Up Trouble show?

While construction equipment pollution adds to overall regional air pollution, people who live near or work at construction sites have a higher risk of exposure to diesel pollution from construction equipment. Our Construction Risk Zone analysis indicates that risk of exposure to construction activity is widespread throughout populated areas of California, but 90 percent of construction pollution-related health endpoints occur in the five most populated air basins. Higher risk of exposure to operating construction equipment occurs both in population-dense cities and in suburbs where large construction projects are accompanying population growth. 

How were health endpoints attributed to construction equipment pollution? 

Data from the California Air Resources Board's pollutant emission inventory and air pollution monitoring data were used to estimate construction equipment's contribution to regional air pollution. Peer-reviewed epidemiological studies that establish links between elevated levels of air pollution and increased hospitalizations, premature deaths, and other health conditions were then used to estimate the health damage from construction equipment pollution. 

What does the new California clean construction regulation require construction equipment owners to do?

See the UCS fact sheet on the 2007 clean construction regulation.

Why not wait for new equipment?

Californians will continue to suffer from increased hospitalizations for heart and lung disease, asthma attacks, acute bronchitis, and premature death for the next two to three decades if we wait for new, cleaner equipment to replace older equipment. For example, if California proceeds on a business-as-usual course, half of all bulldozers purchased new in 1995—before any emission controls for particulate matter existed—will still be operating without pollution controls in 2024. 

What can be done to reduce emissions from today's construction equipment?

There are options available today to achieve significant reductions from construction equipment already in use: 

  • Repower. The body or chassis of some equipment can last many decades beyond the life of the original engine. Installing a new low-emission engine in an older chassis can allow the machine to run cleanly for many more years. California's Carl Moyer incentive program is currently funding some repower projects for construction equipment.
  • Retrofit. Existing engines that can be expected to run for many more years can be retrofitted with emission control technologies that reduce PM more than 90 percent. Some options exist today, while more are expected to be available over the next few years.
  • Replace. Replacing old equipment with a new lower-emission model ahead of schedule can result in substantial pollution reductions and maintenance and fuel cost savings. 

What is the risk of living near construction sites?

Exposure to elevated levels of fine particulate matter has been linked with various adverse health endpoints including exacerbation of asthma attacks, heart and lung disease, and cancer. Living and working in close proximity to a construction site may increase the level of exposure to fine PM; actual exposure levels depend on numerous factors including wind patterns, the amount of equipment operating, the age of the equipment, and how long it operates. Since construction equipment comes and goes from construction sites, pollution levels at or near a site are ever-changing. Implementation of the recently adopted statewide regulation will achieve broad reductions across the entire construction fleet and help protect all of California's workers and residents.

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