Jump to main content or area navigation.

Contact Us

Particulate Matter (PM)

Agriculture

THE U.S. ENVIRONMENTAL PROTECTION AGENCY’S
COARSE PARTICULATE MATTER (PM10) STANDARDS AND AGRICULTURE
FACT SHEET

February 17, 2011

WHAT EPA IS DOING

  • The U.S. Environmental Protection Agency is in the midst of a regularly scheduled review of its national ambient air quality standards (NAAQS) for particle pollution, also called particulate matter or PM.  The Clean Air Act requires EPA to conduct this review every five years to ensure that the standards adequately protect public health and welfare, and reflect the best available science for each air pollutant. 
  •  When EPA reviews an air quality standard, it is required to issue a proposal – even if the agency is recommending keeping the existing standard in place. The Agency can propose to keep a standard, to revoke it, or to revise it. The actions must be based on science and ensure that public health is protected as required by law.
  • EPA has not made any decisions on the standards at this time. As part of this Clean Air Act Review, EPA is examining its existing 24-hour standards for particles 10 micrometers in diameter and smaller, called PM 10 or “coarse” particle pollution. Those standards have been set at 150 micrograms per cubic meter of air since 1987. The law requires EPA to set two standards: a primary PM10 standard, designed to protect public health, and a secondary standard, designed to protect the public welfare (from damage to visibility, and environmental harm, such as damage to lakes and streams).
  • EPA also is reviewing the standards for fine particles, known as PM2.5.
  • EPA staff are continuing to work on their final draft of a “policy assessment document” for particle pollution. That document is not an official Agency position or decision; rather, it provides options for EPA leadership to consider when determining what to include in the upcoming proposal on the PM standards.  So far, EPA’s review of the science leaves the full range of possible options available for consideration.
  • The Agency anticipates issuing a proposal in 2011. EPA must issue a proposal if it is recommending changing a standard, or keeping an existing one.  The proposal will undergo public review and comment before EPA makes any final decisions.

WHAT THE EXISTING PM10 STANDARDS HAVE MEANT FOR AGRICULTURE

  • Protecting and improving our nation’s air quality is the work of a federal-state partnership established in the Clean Air Act. EPA issues national air standards and designates the “nonattainment areas” that must reduce pollution in order to meet them, generally basing these designations on data collected at air quality monitors. States then determine what those pollution reduction steps will be and outline those steps in plans known as “state implementation plans.”
  • Like all national air quality standards, the existing PM10 standards set the amount of PM10 pollution allowed in the outdoor air. But the standards themselves do not establish emission control requirements for any particular industry, including agriculture, and EPA has not required emission controls on farmland in order to meet the standards. Each state determines how to reduce a nonattainment area’s pollution to meet the standards in a way that makes the most sense for that area.
  • The vast majority of states have not required the agriculture industry to take any actions that require PM10 emission reductions; focusing their efforts to reduce PM10 on sources such as industrial processes, and construction and demolition. California and Arizona are addressing PM10 from agriculture by incorporating conservation management practices developed with growers and USDA into PM10 implementation plans for some nonattainment areas.
  • Similarly, EPA PM10 monitoring requirements do not target rural areas. EPA requires PM10 monitoring in areas with populations of 100,000 or more, with more monitors required in areas of higher population and with higher PM10 levels. States have the discretion to site additional PM10 monitors to meet their own clean air objectives.

COARSE PARTICLES AND HEALTH

  • A particle that is 10 micrometers in diameter is extremely small and can get past the respiratory system’s natural defenses (the nose and throat). For comparison, the diameter of an average human hair is about 70 micrometers -- seven times larger than the largest coarse particle.
  • Scientific studies have linked exposure to coarse particles to a variety of health problems, including hospital admissions for heart disease, hospital admissions and doctors’ visits for respiratory diseases, increased respiratory symptoms in children, and premature death in people with heart or lung disease.

THE REVIEW OF THE PM10 STANDARDS

  • Reviews of a national air quality standard are thorough and extensive, taking several years before EPA reaches the point of proposing a rule. For PM10, the review to date has included:
    • A “integrated science assessment,” which is a review of the most recent science about the pollutant and its effect on public health and the environment.
    • A staff “policy assessment document.” This document, previously known as a “staff paper,” includes staff conclusions about the current standard and possible alternative standards for the Administrator to consider.
  • EPA has completed two drafts of the staff policy assessment. EPA’s independent science advisors, the Clean Air Scientific Advisory Committee (CASAC), have reviewed both drafts, and the public has had the opportunity to comment on them. EPA staff are working to finalize the policy assessment document.
  • In the second draft of the policy assessment, the staff concludes that scientific evidence could support either keeping the current PM10 standard, or revising it. The staff note that if the standard were revised, the form of the standard (the way EPA calculates whether an area is violating a standard) also would need to be changed. EPA has not made any decisions at this time. 
  • The existing PM10 standard, of 150 micrograms per cubic meter, was set in 1987. It is what is known as a “one expected exceedance” standard, meaning that an area is violating if it exceeds the standard more than once a year, on average, over a three-year period. EPA staff have concluded that the science could support keeping this standard.
  • EPA staff also have examined alternative standards that are based on what is called “the 98th percentile form.”  Using that form, an area would meet the standard if the 98th percentile of 24-hour PM10 concentrations in a year, averaged over three years, was at, or below, the level of the standard. EPA staff also have concluded that the science could support revising the standard, in a range of 65 to 85, but only if the form of the standard also is changed.
  • The CASAC has recommended that EPA revise the current PM10 standard to use the 98th percentile form, and recommended the level be set between 65 and 75 micrograms per cubic meter.

FOLLOWING THE SCIENCE:  HOW PM REGULATIONS HAVE CHANGED OVER TIME

  • EPA has regulated particle pollution since 1971. Our standards have evolved over time, as science has taught us more about how exposure to particles affects health and welfare.
  • The 1971 standards, for example, set levels for all particles in the air, known as “total suspended particulate.” This covered all sizes of airborne particles, including dirt and other larger particles.
  •  In 1987, EPA changed the standards to focus on those particles 10 micrometers in diameter and smaller, because particles larger than that don’t generally get past the nose into the respiratory system. The Agency set both daily and annual PM10 standards at that time.
  • In 1997, based on an expanding body of scientific evidence linking fine particles (PM2.5) to serious health effects, EPA added both daily and annual standards for fine particles.
  • The Agency revised those standards in 2006, tightening the daily standard. That same year, EPA revoked the annual standard for PM10, because there was insufficient evidence linking long-term exposure to inhalable coarse particle pollution to health problems. EPA retained the daily PM10 standard – at 150 micrograms per cubic meter, the same level since 1987.

 

Jump to main content.