Toxic Gas Program

​The purpose of the Toxic Gas Program is to protect public health and property from the hazardous conditions arising from the use, distribution, handling, and dispensing of toxic gas. Toxic gases are gases with lethal concentrations (LC50 <5,000ppm). There are three different classes Class I, II, III. Class I are the most toxic gases. More controls are required for more toxic gases.


Santa Clara County Code of Ordinances, Title B, Division B11, Chapter XIV


HMCD oversees the Toxic Gas Program for facilities located in the cities of Los Altos Hills and Monte Sereno and in the unincorporated areas of Santa Clara County (including Moffett Field and Stanford).

General Requirements

  • ​The following controls are required of all facilities subject to TGO pursuant to SCCO B11-380:
    • Tanks and piping systems used for regulated materials are in accordance with seismic protection provisions.
    • Facilities are secured against unauthorized entry.
    • On-site emergency response personnel must be provided with at least two self-contained breathing apparatuses (SCBA) and other appropriate protective equipment. The SCBAS must be suitable for use with the regulated materials at your facility and stored in a readily available location that would not likely be immediately affected during a release.
    • Incompatible regulated materials must be separated by one hour fire-resistive construction or by the use of separate gas cabinets. Construction materials must be compatible with the toxic gases based on nationally recognized standards.
    • Containers of regulated material must be tested for leaks upon delivery and prior to departure by an approved testing method. Appropriate remedial action must be taken if a leak is detected.
    • Protective plugs and caps of regulated materials must be in place at all times up until the material is properly placed into use.
    • A written emergency response plan must be prepared and filed with the Department and the local fire agency.
    • Designate an on-site emergency response team composed of responsible persons who meets the following requirements:
      • Prepared to respond in an emergency.
      • Adequately trained on all on-site locations where regulated materials are stored, handled, and used.
      • Familiar with the emergency response plan and the associated risk with the regulated materials
      • Able to serve as a liaison to the Fire Department
    • Emergency drills for each on-site emergency response team must be conducted at least once every three months. Maintain written records of drills at facility for three years and are available for inspection upon request of the Department and local fire agency.
    • All safety control systems at your facility must be maintenance and tested by a qualified person at least annually and maintained in good working condition. Maintenance records of testing must be available upon inspection or request from the Department.
    • All interior and exterior use areas and all indoor storages areas and buildings must be protected by automatic sprinkler system designed in accordance with the current edition of NFPA for ordinary hazardous group II. If your facility stores regulated materials that are incompatible with the use of a sprinkler system, the local fire agency may require alternative forms of fire protection.
  • Additional controls are required based on the classification of your material. Consult SCCO B11 - 381 through B11-385 for additional control requirements.
  • Pay an annual invoice to keep your permit active.​

Forms & Documents

If you have further questions or need additional guidance pertaining to the Toxic Gas Program, please contact HMCD at (408) 918-3400 or at [email protected].


For information on Toxic Gas Facility Permit Fees, click here.

Frequently Asked Questions

If you would like answers to frequently asked questions about Toxic Gases, click here.​​

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