Air Quality
The Texas Commission on Environmental Quality (TCEQ) defines ambient air quality as the quality of the air in the environment around us, outside of buildings and industrial facilities. It refers to the concentration of pollutants in the air that people breathe. This includes measurements of various air pollutants, such as ozone, particulate matter, carbon monoxide, sulfur dioxide, and nitrogen dioxide. Ambient air quality assessments help determine if the air meets established health and safety standards, and whether it is safe for the public and the environment.
Note: The following is an extended excerpt from a similar air permit request.
Executive Director’s Response to Public Comment
Dry Creek Materials, LLC, Standard Permit Registration No. 174388
Comment 1: Health Effects/Air Quality
Commenters expressed concern about the effect of the emissions from the proposed project on the air quality and health of people, particularly sensitive populations such as the elderly, children, and people with existing medical conditions. Commenters specifically expressed concern about the potential emissions of crystalline silica. Commenters also asked whether the proposed project could cause or exacerbate negative health effects, including cancer, respiratory disease, and asthma.
Response 1: During the development of the Standard Permit, the Executive Director conducted an extensive protectiveness review to ensure protectiveness of human health and the environment. The protectiveness review determined potential impacts to human health and welfare or the environment by comparing emissions allowed by the standard permit to appropriate state and federal standards and guidelines. These standards and guidelines include the National Ambient Air Quality Standards (NAAQS) and TCEQ rules. As described in detail below, the Executive Director determined that the emissions authorized by the standard permit are protective of both human health and welfare and the environment.
The United States (U.S.) Environmental Protection Agency (EPA) created and continues to evaluate the NAAQS, which include both primary and secondary standards, for pollutants considered harmful to public health and the environment. Primary standards protect public health, including sensitive members of the population such as children, the elderly, and those individuals with preexisting health conditions. Secondary NAAQS protect public welfare and the environment, including animals, crops, vegetation, visibility, and buildings, from any known or anticipated adverse effects from air contaminants. The EPA has set NAAQS for criteria pollutants, which include carbon monoxide (CO), lead (Pb), nitrogen dioxide (NO2), ozone (O3), sulfur dioxide (SO2), particulate matter less than or equal to 10 microns in aerodynamic diameter (PM10), and PM less than or equal to 2.5 microns in aerodynamic diameter (PM2.5). The Standard Permit is designed to be in compliance with the NAAQS.
The primary contaminants that have the potential to be emitted from the plant are dust particles having particle sizes of PM10 and PM2.5. All the potential dust concentrations, as well as emissions from combustion sources, have been evaluated using reasonable worst-case operating parameters and compared to the federal criteria mentioned above.
During the protectiveness review, TCEQ performed an Air Quality Analysis (AQA), which included air dispersion modeling that was inherently conservative and tended to over-predict ground-level concentrations of emissions. The emission generating facilities or activities included in the AQA were material handling operations, rock and concrete crushing, stockpiles, and an internal combustion engine to generate power for equipment at the site. TCEQ calculated emission rates using conservative emission factors and methodology from the EPA in the Compilation of Air Pollution Emission Factors, AP-42 manual. TCEQ ensures the conservative nature of these calculations by evaluating each emission point at the maximum material throughput on an hourly basis. The analysis also conservatively assumes the operating schedule of facilities or activities at the site using a maximum annual operating limit of 2,640 hours per year, while stockpile emissions were evaluated as active for 8,760 hours. The air contaminants evaluated were PM, PM10, PM2.5, silica, and products of combustion from the engine, SO2, CO, and NO2.
TCEQ applied the model in a screening mode to ensure predictions were conservative (higher than expected concentrations) and applicable for any location in the state. For example, the protectiveness review evaluated both rural and urban dispersion coefficients and the higher of the two was used as the maximum predicted concentration for developing the conditions of the Standard Permit for Rock and Concrete Crushers. The model also incorporated five years of meteorological data, including wind directions, which were worst-case, short-term meteorological conditions that could occur anywhere in the state. In addition, all emissions sources were co-located in order to minimize bias due to source configuration and wind direction. This technique also provided conservative results since the impact from all sources was maximized. The results of the protectiveness review for all pollutants authorized by the Standard Permit for Rock and Concrete Crushers demonstrated that emissions will not exceed any state or federal standards, including the NAAQS and are protective of human health and the environment.
Crystalline silica (quartz) within the crushed material was also evaluated during the protectiveness review. The results were compared to the effects screening levels (ESLs) in place at the time of the review. ESLs are screening levels used in TCEQ’s air permitting process to evaluate the potential for effects to occur as a result of exposure to concentrations of constituents in the air. The ESL is a conservative guideline concentration that is meant to serve as a screening tool that has multiple built-in safety factors and is considered to be protective of the general population, which includes the very young, the elderly, and people with preexisting health conditions.
Additionally, TCEQ has reviewed ambient air crystalline silica levels measured near aggregate production operations (APOs) in various locations throughout the United States where data are available. These facilities may have comparable air emissions to this proposed facility due to the similar operations and processes. The data indicate that the contribution of respirable crystalline silica from these facilities to ambient levels of particulate matter is negligible or minimal, and the levels are generally below the health-based air monitoring comparison values for crystalline silica developed by TCEQ.
TCEQ’s jurisdiction is established by the Legislature and is limited to the issues set forth in statute. Accordingly, TCEQ does not have jurisdiction to enforce employee safety regulations promulgated by the Occupational Safety and Health Association (OSHA) or to consider employee health when determining whether to approve or deny an application for an air authorization.