Monday, August 13, 2012

Chevron Fire and Air Quality in the East Bay

On the evening of August 6, 2012 a fire broke out at the Chevron Refinery in Richmond, CA. The fire began in a crude oil unit, where there was a leak and was contained that evening, but a small controlled burn was allowed to reduce pressure in the system. Area residents were told to stay inside with windows closed for more than five hours before the all clear was given by the Contra Costa County Health Department.

The Bay Area Air Quality Management District (Air District) responded to the emergency and took eight air samples during the fire. After analysis of the samples for 23 chemical compounds the Air District reported that they found only acrolein levels above the Reference Exposure Level, REL. The Air District noted that throughout the Bay Area acrolein levels are commonly above the REL (not exactly comforting). Reportedly, acrolein levels routinely range between 1 and 4.5 parts per billion. The Air District stated in their news release that “(t)hese concentrations were similar to the “background” levels measured throughout the Bay Area by our monitoring network.”

While this sounds comforting this report by the Air District can be misleading. First of all the data is incomplete and second there are three types of REL, Acute (1 hour exposure), 8 hour (which may be repeated) and chronic. When the Air District spoke of REL they were referring to the acute level, not normal everyday background levels. According to Cal EPA “The acute REL is an exposure that is not likely to cause adverse effects in a human population, including sensitive subgroups, exposed to that concentration for one hour on an intermittent basis.” These health based acute RELs apply to spills, leaks, or other discharges to the ambient air that results from routine operation of a facility and predictable process upsets or leaks.”

Cal EPA determined the concentration level at which no adverse health effects are anticipated for a short term. The acute RELs are based on the most sensitive populations reporting of adverse health effects in the medical and toxicological literature. RELs are designed to protect the most sensitive individuals in the population by the inclusion of margins of safety. Margins of safety are incorporated into the REL to address data gaps and uncertainties, exceeding the REL does not automatically indicate an adverse health impact. The acute REL was the “background” levels that the Air District referred to. More importantly, the data from the Air District is not yet complete. There was no measurement of particulates.

According to reports in the San Francisco Chronicle there was a huge cloud of smoke and hundreds of people went to the hospital to seek treatment. The most likely source of health impacts from the fire is particulate matter from smoke. The Air District does not yet have any data to release on particulate concentrations downwind from the Chevron refinery. For some reason the stationary continuous particulate monitors for the Air District in the local area are upwind of the refinery. The Air District says samples were taken in San Pablo, two miles from the Chevron facility following the fire and are being analyzed for particulate matter levels. Results are expected in the next two weeks, but there is only a small chance that the regularly scheduled monitoring time will have caught the smoke cloud.

Particulate matter is made up of particles that are emitted directly, such as soot and dust, as well as secondary particles that are formed in the atmosphere from reactions of precursor pollutants such as oxides of nitrogen (NOx), sulfur oxides (SOx), volatile organic compounds (VOCs), and ammonia (NH3). Particle are either directly emitted or formed in the atmosphere. Directly-emitted particles come from a variety of sources such as cars, trucks, buses, industrial facilities, power plants, construction sites, tilled fields, unpaved roads, stone crushing, and burning of wood. Other particles are formed indirectly when gases produced by fossil fuel combustion react with sunlight and water vapor. Many combustion sources, such as motor vehicles, power plants, and refineries both emit particles directly and emit precursor pollutants that form secondary particulates. Ammonium nitrate and ammonium sulfate are the principal components of secondary particulates.

Particulate matter has immediate health impacts: itchy, watery eyes, increased respiratory symptoms such as irritation of the airways, coughing or difficulty breathing and aggravated asthma. Health effects can result from both short-term and long-term exposure to particulate pollution. Exposure to particles can also trigger heart attacks and cause premature death in people with pre-existing cardiac or respiratory disease. People most sensitive to particulate pollution include infants and children, the elderly, and persons with existing heart and lung disease. The particles can travel deep into the lungs, enter the bloodstream, and penetrate into cells. Smaller particles can penetrate deepest, causing the greatest harm. Researchers are still trying to identify which types and sources of particles are most hazardous to human health. Though, particles created from combustion soot tend to be fine particles with diameters smaller than 2.5 microns (PM 2.5) which are the most dangerous because it lodges in the lungs. Dust is mostly coarser particles.

According to the Lung Association, the two biggest air pollution threats in the United States are ozone and particle pollution. The United States Environmental Protection Agency, U.S. EPA requires states to monitor air pollution to assess the healthfulness of air quality and ensure that they meet minimum air quality standards. The US EPA has established both annual and 24-hour PM2.5 air quality standards (as well as standards for other pollutants). The annual standard is currently 15 ug/m3 (an AQI of 49). The 24-hr standard was recently revised to a level of 35 ug/m3 (an AQI of 99). The EPA is proposing new air quality particulate standards to go into effect in December 2012. The proposed annual average particle pollution will be lowered to 12-13 ug/m3. The maximum 24 hour standard will remain unchanged at 35 ug/m3. The Bay Area Air District does not have a live feed for their particulate pollution levels like some regions of the state.

The Bay Area's cool, coastal climate safeguards the region against some factors that exacerbate pollution, such as high temperatures and stagnant air flow. Nonetheless, the Bay Area is a nonattainment area due to persistent smog. Santa Clara, Solano and Contra Costa counties had more than 12 high particle pollution days last year of record. A study of children in Southern California showed lung damage associated with long-term particulate exposure, and a multi-city study found decreased lung function in children associated with long term particulate exposure. Many scientific studies have linked exposure to excess particulates to aggravated asthma, increased respiratory symptoms like coughing and difficult or painful breathing, chronic bronchitis, decreased lung function, heart attack and premature death. According to American Lung Association State of the Air Report, Pittsburgh, PA had the highest particle pollution in the nation on an annual basis and Bakersfield, CA had the highest number of days exceeding the daily level. Seven cities averaged particulate levels higher than the 15 ug/m3 current standard allows: Bakersfield, CA; Hanford, CA; Los Angeles, CA; Visalia, CA; Fresno, CA; Pittsburgh, PA; and Phoenix, AZ.

No comments:

Post a Comment