Significant Risk Facilities

A significant risk facility is a business operation that releases toxic substances into the air, when those substances have the potential to cause health problems to people who live and work nearby. Health risks can be cancer or non-cancer related, and non-cancer health risks are further divided into acute (short-term) and chronic (long-term) risks.

Under the California Air Toxic Hot Spots and Information Act, significant risk facilities are required to notify the public of the risks they create and are required to reduce those risks to less-than-significant levels.

Explanation of Risk

Definition of Significant Risk

Putting Risk into Perspective

Requirements of Significant Risk Facilities

Santa Barbara County’s Remaining Significant Risk Facilities

Santa Barbara County’s Historical Significant Risk Facilities

Explanation of Risk

In this program, a health “risk” is the possibility that people will experience health problems from breathing certain toxic substances in the air. Everyone has the possibility of developing cancer or other illnesses. Our exposure to some substances can increase our chance of developing these illnesses – meaning we are more likely to develop them than someone who has not been exposed. The increased risk is estimated using computer models and performing what we call risk assessments, which take into account a number of factors including: the amount and toxicity of the substance; weather conditions; distance from the source of the substance to people; the age, health and lifestyle of people living or working near the source of the substance; and the amount of time people have been exposed to the toxic substance.

“Increased cancer risk” describes the increased chance of getting cancer from exposure to an air toxic. It’s expressed as a probability: the chance of so many additional people getting cancer in a group of one million people.

Non-cancer health risks can include acute, or short- term health problems such as eye irritation, respiratory irritation, and headaches, and chronic, or long-term problems such as permanent damage to organs, the central nervous system, or reproductive functions, and developmental problems in children. Non-cancer health risk is defined by something called the “Hazard Index” (HI). The HI is a ratio of the predicted exposure concentration of the facility’s reported emissions to a concentration considered acceptable to public health professionals. For example, an HI of 2 means the concentration of toxics in the air at the point of exposure is predicted to be twice as high as is generally thought to be safe. The levels defined as “safe” are designed to protect the most sensitive individuals in a population.

It’s important to note that risk numbers do not refer to actual cases of health problems that will occur from exposure to air toxics. The risk assessments are computer calculations that are designed to provide a tool to identify and reduce possible negative health effects. For more information, see Putting Risk in Perspective.  For additional resources on understanding risk and risk assessments see the reference material listed below.

Definition of Significant Risk

The current thresholds that define a significant risk, set and approved by APCD’s Board of Directors, are:

  • for cancer risk, 10 or more excess cancer cases in a population of one million people (stated as “10 in a million”) and,
  • for non-cancer acute and chronic risk, a hazard index greater than 1. The HI is a ratio of the exposure concentration of the facility’s reported emissions to a concentration considered acceptable to public health professionals.

Putting Risk into Perspective

Every day, Santa Barbara County residents are exposed to toxic air contaminants from automobiles, homes, businesses, and natural sources. Many of these substances such as benzene, 1,3-butadiene, diesel soot, and perchloroethylene can cause cancer. The risk posed by these sources is called the “background” cancer risk. This is the chance that anyone living in the area will develop cancer in their lifetime.

The risk from individual businesses’ toxic air emissions is generally less than the background risk. The health risk estimates for these facilities calculate only the additional (above and beyond background) cancer risk caused by their emissions.

Among the largest contributors of air toxics are cars and trucks. A recent study by the South Coast Air Quality Management District reported that diesel particulate, or soot, accounted for 71% of the total cancer risk from toxic air pollution in their region. The study is one of the most comprehensive studies of urban toxic air pollution ever performed.

The estimated background cancer risks due to air pollution for some selected areas of Santa Barbara County are as follows:

Downtown Santa Barbara: 524 cancer cases per million
Santa Maria: 98 cancer cases per million
Gaviota: 47 cancer cases per million
Lompoc: 40 cancer cases per million


While this puts the risk from individual businesses in perspective, it does not imply that the risk from these individual businesses is acceptable or insignificant. Emissions from a particular business can create a “hot spot” where individuals can be exposed to compound risks.

Requirements of Significant Risk Facilities

1. Preparation and Submittal of an Air Toxics Emission Inventory Plan and Report document, updated every four years:

A company which emits toxics into the air must conduct a complete inventory of all of the toxic air pollution it generates. For the smaller companies, which make up the vast majority of the businesses subject to the law, the Air Pollution Control District prepares the inventory for them as a group.

2. Risk Assessment, updated every four years:

A Hot Spots risk assessment is an estimate of the human health risk caused by toxic air emissions from a business. It is a study that quantifies  the possible adverse health effects which may result from exposure to routine emissions of toxic air contaminants. The health risk assessment cannot predict health effects; it only describes the increased possibility of adverse health effects. A risk assessment quantifies the probability of developing cancer and/or other disease from exposure to toxic air contaminant emissions. It is a key step in the Hot Spots program because it lays the groundwork (if a facility is of significant risk) for the public notification and risk reduction processes described below.

3. Public Notification

The primary goal of notification under the Air Toxics “Hot Spots” Program is to inform potentially exposed individuals of significant health risks associated with toxic air emissions routinely released from facilities in Santa Barbara County. The significant risk facilities’ first public notification letters were sent to the affected public in the Spring of 1999.  Subsequent letters were sent for individual facilities following the preparation of updated health risk assessments.

4. Risk Reduction

If the results of a facility’s health risk assessment indicate a significant health risk, the facility operator is required to conduct an airborne toxic risk reduction audit and develop a plan to implement airborne toxic risk reduction measures. Implementation of these measures must reduce the risk from facility emissions below the significance risk level(s) within five years of the date the plan is submitted to the APCD.

Santa Barbara County’s Remaining Significant Risk Facilities

The following facilities are required to notify the public about significant health risk associated with air toxic emissions, and to reduce the health risk to below the significant level.

Santa Barbara County’s Historical Significant Risk Facilities

The following facilities previously created a significant health risk from air toxics emissions.  These facilities have reduced their risk below the APCD’s significant risk thresholds.  Please note that this is not a complete list.

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New Phone Numbers
The District has new direct lines for all staff, as well as for all of our phone lines, including our main phone number and Complaints line. You can find our new phone numbers on this webpage.

Nuevos números de teléfono
El Distrito tiene nuevos números de teléfono para comunicarse con el personal directamente, así como también para todas nuestras líneas telefónicas, incluyendo nuestro número principal y el de las Quejas. Puede encontrar nuestros nuevos números de teléfono en esta página web.