Urban Air Toxics- A Top Priority 

Since the enactment of the 1990 Amendments to the Clean Air Act (CAA), the U.S. Environmental Protection Agency (EPA) has made the control of urban air toxics a priority. Subsequently, EPA has promulgated numerous regulations and control strategies that are intended to reduce air toxics. One such strategy, the Integrated Urban Air Toxics Strategy, leveraged CAA authority in a comprehensive approach to reduce air toxics emissions from all source types including major industrial sources, smaller stationary sources, and mobile sources such as cars and trucks. This was the first major federal initiative to address cumulative public health risks and adverse environmental impacts posed by exposures to multiple air toxics in local communities. National Emission Standards for Hazardous Air Pollutants (NESHAPs), Maximum Achievable Control Technology (MACT) standards, and residual risk-based standards were among the strategies employed at the federal level that offered significant reductions of measureable air toxics emissions from urban areas. However, the more substantial results have come from additional programs adopted by individual state and local agencies. While many states have elected to take the extra steps towards improved controls, it is the State of California that is pioneering toxic emissions control through the use of ambient air quality monitoring technologies coupled with unprecedented enforcement implications.

The Genesis: California Assembly Bill 2588

In September 1987, California adopted Assembly Bill 2588 (AB 2588), the Air Toxics “Hot Spots” Information and Assessment Act. At the time, AB 2588 was the most expansive air toxics regulatory program in the United States. Affecting thousands of industrial facilities throughout California, AB 2588 EQ Spring 2018_Article 2 pic 1established a comprehensive regulatory structure for identifying, prioritizing, and reporting sources of air toxics, which could range from a small auto-body shop to a large, complex chemical plant. The bill required affected facilities to quantify and report on all regulated air toxics every four years. Regional air districts then use the reported data to prioritize facilities-facilities receiving the highest priority would then be required to perform air dispersion modeling as part of a Health Risk Assessment (HRA), in order to estimate acute and chronic health risk impacts on surrounding populations.


AB 2588 was also one of the first air toxics regulations to specify an “acceptable” level of health risk exposure for cancer and other health risk impacts. The provisions dictate that any facility reporting an excess cancer risk greater than 10 in 1 million is obligated to notify the affected population(s) and conduct community meetings for local awareness. Facilities exceeding 25 in 1 million of excess cancer risk have additional obligations to reduce health risk impacts with pollution controls, process changes, or other plant modifications.

With more than 30 years of supporting data, AB 2588 continues to serve as a prime example of a successfully managed statewide air toxics control program.

Ultimately, the impact of this bill would stretch far beyond its origins, setting the stage for a new era of “community based” air toxics regulations in California and potentially, for other states.


Air Toxics Control Evolves with Shift to the Community

Signed into law in July 2017, Assembly Bill 617 (AB 617) expanded California's air toxics regulations to require community-based air monitoring to help quantify the associated risk to affected populations. The bill sets a deadline of October 2018 for the California Air Resources Board to work with the local air districts to identify high-priority locations for subsequent district deployment, by July 2019, of air monitoring stations. Most of the high-priority locations will comprise economically disadvantaged neighborhoods within highly industrialized areas, specifically targeting  facilities that are suspected to pose a high risk for producing excessive air toxics emissions. While AB 2588 required facilities to report their own health risk impacts every four years, AB 617 has given California air districts the unprecedented authority to proactively monitor facilities on a continuous basis. The air districts are also required to develop and implement site-specific monitoring plans that collect data on ground-level concentrations of regulated air toxics of concern such as formaldehyde, benzene, hydrogen sulfide, and hexavalent chromium. The data collected by the community air monitoring stations will then be uploaded to a statewide, publicly accessible database. If the data from any of the targeted facilities exceeds the pre-defined “acceptable” risk thresholds (i.e., cancer risk exceeding 10 in 1 million), the air districts are expected to either pursue enforcement actions against the culpable facilities, require compliance with risk reduction measures, or employ a combination of enforcement and risk reductions under authority provided by AB 2588 or existing local source-specific rules. This expanded regulatory and enforcement effort will place a significant burden on targeted facilities to control all potential emission sources of regulated air toxics, including stacks, fugitives, and area sources.

The community-based monitoring approach of AB 617 is based in part on two major community-based monitoring networks managed by the South Coast Air Quality Management District (SCAQMD) since 2016 in the cities of Paramount and Compton. Each site is outfitted with monitoring networks targeting suspected sources of hexavalent chromium, specifically from metal finishing operations, including chrome plating and anodizing plants. The individual sites include up to 35 separate monitoring stations, which are strategically located near industrial facilities.

The extensive monitoring has resulted in SCAQMD enforcement actions at numerous metal finishing operations; in addition, several air district rules have been amended to further control toxic emissions from the metal finishing industry. The activities surrounding the SCAQMD's efforts in Compton and Paramount are now serving as a regulatory model for community-based enforcement initiatives in other air districts under AB 617.

Refineries Receive Special Focus

Petroleum refineries are among the largest stationary sources of criteria pollutants and toxic emissions in the United States. In recent years, community concerns over toxic emissions from petroleum refineries and the potential health risks to exposed communities have increased. As such, refineries have become a major focus of rulemaking activities both locally and nationally. 

In December 2015, U.S. EPA promulgated a final rule in 40 CFR Part 63.658 that will further control toxic emissions from petroleum refineries. For the first time in a federal regulation, this rule requires petroleum refineries to continuously monitor benzene concentrations at fencelines to ensure appropriate management of toxic emissions from fugitive sources such as waste treatment and leaking components.

Aligned with EPA's direction and yet in a much expanded manner, the Bay Area Air Quality Management District (BAAQMD) developed and promulgated a new rule (Regulation 12, Rule 15: Petroleum Refining Emissions Tracking) requiring five area refineries to increase air monitoring activities for multi-pollutants, including benzene and other representative compounds, using real-time open path/remote sensor technologies at the refinery fencelines.

A similar localized regulatory effort has now been initiated in Southern California. In December 2017, SCAQMD's Rule 1180, Refinery Fenceline and Community Air Monitoring, mandated that eight petroleum refineries begin collecting real-time data of refinery air pollutant emissions at or near their properties' boundaries or fencelines, with the resulting data to be made publicly accessible in an expeditious manner.

This unprecedented approach of local air districts requiring fenceline monitoring at petroleum refineries in Southern California and the Bay Area led to the passing of yet another new piece of California legislation in 2017-AB 1647, which requires that all petroleum refineries in California develop, install, operate, and maintain air monitoring systems at or near their boundaries or fencelines. All necessary systems must be installed by January 1, 2020. AB 1647 also requires the refineries to collect real-time monitoring data, make the measured data available as promptly as possible in a publicly accessible format, and maintain comprehensive data records. Although no specific emission limits associated with the refinery fenceline monitoring requirements are included in AB 1647 or the local districts' rules, it is highly probable that the respective agencies will use the collected data to identify sources of elevated pollutant emissions. Identifying these sources could lead to the development of a new rule or amendments to the existing rules to further control air toxic emissions, in addition to enforcement action as in the case of the metal finishing industry in Paramount and Compton under SCAQMD jurisdiction.

Community-Based Air Toxics Monitoring: Coming Soon to a Town Near You?

Under its CAA authority, EPA has promulgated many standards to regulate and reduce air toxics emissions from various industrial sources to protect health and prevent adverse environmental effect. However, state and local regulatory programs are often more effective in controlling toxic emissions and addressing air toxics concerns at a local level. 

Starting with early efforts by the BAAQMD and SCAQMD and now expanding statewide with the legislative mandates of AB 617 and AB 1647, California has entered a new era of community-based air toxics monitoring and enforcement. These activities will likely lead to additional regulations and requirements for other potential emission sources of regulated air toxics, including stacks, fugitives, and area sources.

These changes in the California regulatory landscape with respect to air toxics programs could pave the way for other states to adopt comparable community-based air toxics monitoring and enforcement initiatives. As with its pioneering greenhouse gas legislation (AB 32, the California Global Warming Solutions Act), California's approach to reducing air toxics may set the stage for other state and local jurisdictions to follow suit.