Achieving progress toward better air quality
On Dec. 31, 1970, 29 days after establishing the U.S. Environmental Protection Agency, President Richard Nixon signed the Clean Air Act. This action resulted in a major shift in the federal government’s role and enforcement authority in air pollution and established four major regulatory programs, two of which are the focus in recent actions undertaken by the Imperial County Air Pollution Control District: the National Ambient Air Quality Standards (NAAQS) and State Implementation Plans (SIP).
NAAQS refers to six principal pollutants considered harmful to public health and the environment. The current standards, which are periodically reviewed and revised, include carbon monoxide, lead, nitrogen dioxide, ozone, particulate matter (PM2.5 and PM10) and sulfur dioxide.
Conversely, SIPs are a collection of regulations and documents used by a state or local air district to describe how an area will reduce air pollution and attain the NAAQS. In addition to extensive documentation, SIPs encompass monitoring records, modeling, permitting, district rules, state regulations, federal controls, emission control strategies, fuel regulations, and many other factors pertaining to the regulation and improvement of air quality.
As EPA continues to set new standards and revise existing NAAQS, the Clean Air Act requires agencies to determine if areas meet the new air quality standards. An area meeting the standards will be designated as an attainment area, whereas an area that does not meet the standards will be one of non-attainment.
Since 2001, Imperial County (technically referred to as the Imperial Valley Planning Area) has been an area of serious non-attainment for PM10, inhalable particles with diameters that are generally 10 micrometers or smaller.
On Oct. 23, 2018, ICAPCD’s board of directors adopted a PM10 SIP, the Imperial County 2018 Redesignation Request and Maintenance Plan for Particulate Matter Less than 10 Microns in Diameter. This plan included ICAPCD’s efforts for maintaining the PM10 standard while also requesting to redesignate the area from non-attainment to attainment for PM10.
Several factors played into the ICAPCD’s request and justification for requesting to be designated as an attainment area. From 2014 to 2016, Imperial County did not violate the federal PM10 standard of less than one exceedance per year averaged over three years, aside from any exceptional events. EPA has defined exceptional events as “unusual or naturally occurring events that can affect air quality but are not reasonably controllable using techniques that tribal, state or local air agencies may implement in order to attain and maintain the NAAQS.” Although multiple exceedances of PM10 were recorded between 2014 and 2016, research found they were due to high wind exceptional events and fugitive dust from natural open areas.
As per the Exceptional Events Rule, these occurrences were excluded from consideration in the evaluation of the region.
Aside from the exceptional events, all concentrations recorded at each of the ICAPCD’s monitoring stations were under the PM10 exceedance standard. Over the past several years, ICAPCD has adopted and implemented various emission control programs that have provided permanent and enforceable reductions in PM10 emissions. Since 2000, PM10 concentration in the Imperial County has been reduced by over half (96 μg/m3 in 2000 compared to 46 μg/m3 in 2016) when excluding the uncontrollable exceptional events.
Even if the exceptional events were taken into consideration, PM10 concentrations would still have dropped by approximately 39 percent in the same 16-year timeframe. These reductions also took into consideration other factors, such as precipitation within Imperial County, and found that the observed reductions in the annual average PM10 concentrations were the result of “permanent, enforceable reductions in PM10 emissions from sources where the District has focused control efforts,” EPA said.
On Sept. 18, under section 110(k) of the Clean Air Act, EPA issued a final ruling approving ICAPCD’s SIP and request to redesignate the Imperial Valley Planning Area to attainment for PM10. These approvals went into effect on Oct. 19. These two monumental actions are a testament of the work by the ICAPCD, advocates, community organizations, and state and federal officials who have quantifiably shown that through coordination and collaboration, we can improve the air quality in our region.
In addition, ICAPCD continues to work with the city of Mexicali through the Imperial-Mexicali Air Quality Task Force to bring awareness to citizens and educate officials on air quality and monitoring matters; our local environmental justice group, Comite Civico del Valle, in co-chairing the AB 617 Community Steering Committee to improve the air quality in the Calexico-Heber-El Centro corridor; Imperial Irrigation District, the Salton Sea Authority and others in mitigating the impacts of the rapidly shrinking Salton Sea; our local agriculture industry in obtaining and implementing new and clean-energy equipment and modifying agriculture burning rules; and many other individual and organizations across our county and state to ensure those who live and work in our border region can breathe the clean air we all deserve.