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How Are Burn Day Decisions Made?

Updated April, 16, 2012

Placer County is divided among three (3) different air basins, Sacramento Valley, Mountain Counties, and Lake Tahoe . The California Air Resources Board (ARB), uses specific criteria (California Code of Regulations-Title 17) to determine the burn day decisions. The Placer County Air Pollution Control District provides this information, on permissive burn days, to the public each day by 8 a.m.

What Are the Specific Title 17 Criteria Used?

  • The criteria are based on a meteorological value called 500-millibar (mb) heights.
  • The height values are obtained from 500-mb forecast weather charts.
  • 500-mb heights typically average 18,300 feet above sea level.
  • High 500-mb heights are related to sinking air through the air column, which tends to be more stable.
  • Stability is a measure of the atmosphere’s ability to lift smoke away from the ground. A more stable atmosphere indicates less plume rise, whereas an unstable atmosphere suggests good conditions for plume rise.

How are the Criteria Used to Determine a NO Burn Day?

Mountain Counties and Lake Tahoe Air Basin

  • A no burn day is declared for the following day if the 500-mb heights are forecasted to be greater than or equal to the specified 500-mb height criteria listed in Title 17.
  • A no burn day may be declared if there are significant smoke or ozone impacts.
  • ARB Meteorologists may also declare a no burn day if he/she establishes other factors that are not conducive to burning.

Sacramento Valley Air Basin

  • The stability of the atmosphere is determined by comparing minimum morning surface temperatures to temperatures aloft.
  • Temperatures aloft are measured by daily aircraft soundings.
  • Morning stability is calculated from the 3,000 foot temperature minus minimum surface temperature.
  • Pollutant levels are also a factor in determining a no burn day. Particulate measurements are gathered throughout the Sacramento Valley.
  • If the stability of the atmosphere is greater than 17° F and particulate measurements are elevated, a no burn day is declared.
  • A no burn day may also be declared if ozone concentrations are forecasted to be unhealthy.

How are the Criteria Used to Determine a Burn Day?

Mountain Counties and Lake Tahoe Air Basins

  • A burn day is declared for the following day if the 500-mb heights are forecasted to be below the specified 500-mb height criteria listed in Title 17.

Sacramento Valley Air Basin Burn Day Criteria

  • A burn day is declared if the meteorological conditions and air quality measurements allow for burning without adversely impacting the air quality of the Valley.
  • The burn decision is issued the morning of the burn/no burn day.

Why are Rainy Days Generally Burn Days?

  • Rainy days are usually associated with lower 500-mb heights.
  • Good smoke dispersion with smoke rising upward.
  • Rain-washes smoke particles out of the air.

WHEN CAN I BURN?

Burning is allowed only on a permissive burn day and in those areas of Placer County that allow burning.

  • For the Greater Auburn Area (within 12 miles) (or for cell phones) - 530-889-6868, or

  • All other areas of Placer County (land lines only) - 1-800-998-BURN (2876) toll-free

  • www.placer.ca.gov/burnday

  • The Air District has established a policy in making federal holidays no burn days in Placer County.

On days when the fire danger is increased, the Air District works very closely with local fire officials to include their information in the burn day message.

For more information, contact the Placer County Air Pollution Control District at (530) 745-2330.

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