SCAQMD to Monitor Particulate Emissions from ExxonMobil Refinery in Torrance during Weekend Startup

May 5, 2016

Community exposures not expected to exceed health-based thresholds

Southland air quality officials will monitor outdoor air pollution levels around the ExxonMobil refinery and in the surrounding community when the refinery starts up a key gasoline production unit this weekend. The unit has been idled since a February 2015 explosion at the plant.

“We are taking a number of steps to protect nearby residents when the refinery starts up and resumes operations,” said Wayne Nastri, Acting Executive Officer of the South Coast Air Quality Management District. “One of those measures includes deploying an air monitoring network to measure fine particulate levels in the air around the refinery during the startup process.”

Real-time, continuous air monitors have been deployed and will be operating before, during and after a six-hour period when ExxonMobil will temporarily deactivate a fine particulate air pollution control unit as a safety precaution.  Air quality officials have deployed monitors at fixed locations and on mobile platforms to measure small-diameter fine particulates (PM2.5 and PM10), the key pollutants expected to be emitted during the six-hour period. These air quality measurements will allow SCAQMD scientists to assess potential air pollution impacts of the startup in the community.

ExxonMobil has planned the six-hour period to occur between 7 p.m. Saturday, May 7, and 7 a.m. on Sunday, May 8.

“Based on our scientific analysis, we do not expect refinery emissions during startup to expose residents to air quality levels that exceed health-based thresholds,” said Jo Kay Ghosh, SCAQMD’s Health Effects Officer.

SCAQMD has created a dedicated web page for the ExxonMobil startup at The site has an overview of the startup process and a detailed discussion of health risk impacts. Following the startup, it will also show the air monitoring results.

Residents can report air quality complaints such as odor, dust, smoke or other air contaminants to SCAQMD’s toll-free complaint line, 1-800-CUT-SMOG, or to its website at

Evaluation of Health Risks

SCAQMD conducted a detailed analysis of exposure to refinery air emissions during startup, including toxic air contaminants and fine particulates. These are the findings:

  • During the six-hour startup period, the maximum potential short-term health risks from catalyst dust are about 100 times lower than health-based thresholds used by SCAQMD. The agency’s scientists calculated this risk taking into account emissions of up to 600 pounds of excess PM in the form of catalyst fine particulates, and a SCAQMD laboratory analysis of the catalyst showing it contains trace levels of the toxic metals nickel, arsenic, selenium, vanadium and copper;

  • The maximum outdoor concentration of hydrogen cyanide gas from the refinery will not exceed any SCAQMD health risk thresholds. Recent testing information from U.S. EPA indicates that ExxonMobil may have hydrogen cyanide emissions as high as 100,000 pounds per year. These emissions will not increase and most likely will be lower during the six-hour period compared to normal operation. Over the course of a year, assuming emissions of 100,000 pounds per year, the expected maximum outdoor concentration of hydrogen cyanide in the community is 0.27 micrograms per cubic meter – more than 30 times less than the Reference Exposure Level set by the state Office of Environmental Health Hazard Assessment, a level at or below which no adverse health effects are expected. Hydrogen cyanide gas is formed as a byproduct of catalyst regeneration during the normal operation of the Fluid Catalytic Cracking Unit (FCCU).

  • Although refinery startup emissions may increase fine particulate levels, they are not expected to exceed state or federal health-based air quality standards. During the six-hour period, the refinery will emit excess particulate that could increase the outdoor concentration by a maximum of about 7 micrograms per cubic meter of PM2.5 and about 8 micrograms per cubic meter of PM10 at the facility’s northern fence line. Weather conditions forecast for the weekend could reduce PM levels; and

  • A 2011 Health Risk Assessment (HRA) prepared based on emissions data from ExxonMobil and approved by SCAQMD and state health officials did not exceed SCAQMD’s thresholds for public notification or risk reduction. The HRA found a maximum cancer risk of 7.7 in 1 million over a 70-year exposure, below SCAQMD’s 10-in-1-million threshold for formal public notification as well its 25-in-1-million threshold for risk reduction. Non-cancer risks also were below risk thresholds.


Refinery Ordered to Minimize Startup Emissions

At an April 2nd public hearing in Torrance, SCAQMD’s independent Hearing Board –after receiving and considering testimony from SCAQMD, ExxonMobil and the public – approved an order for abatement requiring ExxonMobil to provide community notification and take several steps to minimize any excess emissions during the startup of its FCCU and an associated air pollution control unit, known as an electrostatic precipitator (ESP.) These steps include, but are not limited to:

  • Providing 48-hour advance notice to the community – starting today – of the six-hour period when the ESP is not in full use through door hangers and providing information on voluntary signups to TorranceAlerts;

  • Scheduling the six-hour period when the ESP is not in full use from 7 p.m. to 7 a.m., so that it is not during school or business hours;

  • Operating the FCCU regenerator in a manner that would minimize emissions during the six-hour period when the ESP is not in full use;

  • Reducing the refinery throughput from normal operation levels by about one-third down to 100,000 barrels per day;

  • Shutting down two heaters used in the Coker units;

  • Using the upgraded cooling towers with reduced particulate emissions;

  • Performing emissions source tests and continuously monitoring the opacity of particulates from the FCCU stack; and

  • Retiring emission credits for excess nitrogen oxide (NOx) emissions that may occur during a period of 12 hours during start-up.

In a separate action, the SCAQMD agency – and not the SCAQMD Hearing Board – reached a settlement agreement with ExxonMobil requiring the company pay approximately $5 million in penalties for air pollution violations mostly associated with the 2015 explosion and to a smaller extent any violations that could occur during the startup of the FCCU at the refinery.

Half of the monies will be earmarked for projects benefitting the communities surrounding the Torrance facility and impacted community.  SCAQMD’s Governing Board will consider projects to be funded in a future public meeting, with an opportunity for public input on proposed projects.

The SCAQMD is the air pollution control agency for Orange County and major portions of Los Angeles, San Bernardino and Riverside counties.

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