JOURNAL OF f i f t e e n d o l l a r s Environmental Health Published by the National Environmental Health Association www.neha.org Dedicated to the advancement of the environmental health professional Volume 85, No. 2 September 2022
September 2022 • Journal of Environmental Health 3 ADVANCEMENT OF THE SCIENCE Long-Term Trends of Fine Particulate Matter in the Dallas–Fort Worth Metropolitan Area........................................................................................................................ 8 Survival of Listeria monocytogenes in Commercially Available Refrigerated Cold-Brewed Coffee................................................................................................................... 18 ADVANCEMENT OF THE PRACTICE Operational Insights Into Mosquito Control Disaster Response in Coastal North Carolina: Experiences With the Federal Emergency Management Agency After Hurricane Florence........................................................................................................... 24 Building Capacity: Building Capacity With State and Local Data Exchanges. ............................. 32 Direct From AEHAP: Building the Environmental Health Workforce Through Scientific Knowledge and Intentional Collaboration..................................................................... 34 Programs Accredited by the National Environmental Health Science and Protection Accreditation Council. ...................................................................................... 36 Direct From ATSDR: New Web-Based Public Health Assessment Guidance Manual: A Foundational Tool for Evaluating Exposure and Public Health Impacts in Communities............ 38 Direct From CDC/Environmental Health Services: Data-Forward Environmental Health Food Safety Practice......................................................................................................... 42 ADVANCEMENT OF THE PRACTITIONER EH Calendar. ............................................................................................................................. 46 Resource Corner........................................................................................................................ 47 YOUR ASSOCIATION President’s Message: Environmental Health Is a Hidden Treasure............................................................6 Special Listing............................................................................................................................ 48 NEHA News............................................................................................................................... 50 NEHA Annual Financial Statement........................................................................................... 54 NEHA 2023 AEC....................................................................................................................... 56 DirecTalk: Not the Health Police................................................................................................. 58 Preparation for post-hurricane mosquito control is essential for an effective emergency response to protect public health and promote recovery efforts. This month’s cover article, “Operational Insights Into Mosquito Control Disaster Response in Coastal North Carolina: Experiences With the Federal Emergency Management Agency After Hurricane Florence,” is timely as hurricane season in the U.S. runs from June to November, with August to October being the peak months for tropical storms. The article provides practical advice to plan, prepare, and implement a successful ground- and aerialbased mosquito control response. See page 24. Cover image © iStockphoto: ByoungJoo / ronniechua / nickylarson974 A B O U T T H E C O V E R A D V E R T I S E R S I N D E X Custom Data Processing....................................... 31 GOJO Industries................................................... 23 HealthSpace Is Now HS GovTech......................... 60 Hedgerow Software U.S., Inc................................. 37 Industrial Test Systems, Inc.. ................................ 17 Inspect2GO Environmental Health Software. ........ 2 NEHA-FDA Retail Flexible Funding Model Grant Program........................................... 59 Ozark River Manufacturing Co............................. 45 Partnership for Food Safety Education................. 45 The University of Alabama at Birmingham. ........... 5 JOURNAL OF Environmental Health Dedicated to the advancement of the environmental health professional Volume 85, No. 2 September 2022
4 Volume 85 • Number 2 Of f i c i a l Pub l i ca t i on Journal of Environmental Health (ISSN 0022-0892) Kristen Ruby-Cisneros, Managing Editor Ellen Kuwana, MS, Copy Editor Hughes design|communications, Design/Production Cognition Studio, Cover Artwork Soni Fink, Advertising For advertising call (303) 802-2139 Technical Editors William A. Adler, MPH, RS Retired (Minnesota Department of Health), Rochester, MN Gary Erbeck, MPH Retired (County of San Diego Department of Environmental Health), San Diego, CA Thomas H. Hatfield, DrPH, REHS, DAAS California State University, Northridge, CA Dhitinut Ratnapradipa, PhD, MCHES Creighton University, Omaha, NE Published monthly (except bimonthly in January/February and July/ August) by the National Environmental Health Association, 720 S. Colorado Blvd., Suite 105A, Denver, CO 80246-1910. Phone: (303) 7569090; Fax: (303) 691-9490; Internet: www.neha.org. E-mail: kruby@ neha.org. Volume 85, Number 2. Yearly subscription rates in U.S.: $150 (electronic), $160 (print), and $185 (electronic and print). Yearly international subscription rates: $150 (electronic), $200 (print), and $225 (electronic and print). Single copies: $15, if available. Reprint and advertising rates available at www.neha.org/JEH. CPM Sales Agreement Number 40045946. Claims must be filed within 30 days domestic, 90 days foreign, © Copyright 2022, National Environmental Health Association (no refunds). All rights reserved. Contents may be reproduced only with permission of the managing editor. Opinions and conclusions expressed in articles, columns, and other contributions are those of the authors only and do not reflect the policies or views of NEHA. NEHA and the Journal of Environmental Health are not liable or responsible for the accuracy of, or actions taken on the basis of, any information stated herein. NEHA and the Journal of Environmental Health reserve the right to reject any advertising copy. Advertisers and their agencies will assume liability for the content of all advertisements printed and also assume responsibility for any claims arising therefrom against the publisher. Full text of this journal is available from ProQuest Information and Learning, (800) 521-0600, ext. 3781; (734) 973-7007; or www.proquest. com. The Journal of Environmental Health is indexed by Current Awareness in Biological Sciences, EBSCO, and Applied Science & Technology Index. It is abstracted by Wilson Applied Science & Technology Abstracts and EMBASE/Excerpta Medica. All technical manuscripts submitted for publication are subject to peer review. Contact the managing editor for Instructions for Authors, or visit www.neha.org/JEH. To submit a manuscript, visit http://jeh.msubmit.net. Direct all questions to Kristen Ruby-Cisneros, managing editor, email@example.com. Periodicals postage paid at Denver, Colorado, and additional mailing offices. POSTMASTER: Send address changes to Journal of Environmental Health, 720 S. Colorado Blvd., Suite 105A, Denver, CO 80246-1910. Printed on recycled paper. in the next Journal of Environmental Health Estimation of High Blood Lead Levels Among Children: An Application of Bayesian Analysis Exploring Foodborne Illness and Restaurant Cleanliness Reporting in Customer-Generated Online Reviews Lead-Based Paint and Other In-Home Health Hazards: Findings of the Las Vegas Lead Hazard Control and Healthy Homes Program don’t miss NOW AVAILABLE: The updated REHS/RS Study Guide Fifth Edition! EDUCATION & TRAINING Recreated in a fresh visual layout to enhance the reading and studying experience Helps identify content areas of strength and areas where more studying is needed Incorporates insights of 29 subject matter experts Includes 15 chapters covering critical exam content areas Visit our Study References page for more information! NEHA.ORG/REHS-STUDY-REFERENCES C M Y CM MY CY CMY K
September 2022 • Journal of Environmental Health 5 Updated to the 2017 FDA Food Code NEHA PROFESSIONAL FOOD MANAGER 6TH EDITION ◆ Edited for clarity, improved learning, and retention ◆ Content aligns with American Culinary Federation Education Foundation competencies ◆ Prepares candidates for CFP-approved food manager exams (e.g., Prometric, National Registry, ServSafe, etc.) ◆ Discounts for bulk orders and NEHA Food Safety Instructors Professional Food Manager Online Course is also available To order books or f ind out more about becoming a NEHA food safety instructor, call 303.802.2147 or visit neha.org
6 Volume 85 • Number 2 YOUR ASSOCIATION D. Gary Brown, DrPH, CIH, RS, DAAS Environmental Health Is a Hidden Treasure PRES IDENT ’ S MESSAGE As I stated in my last column, environmental health is a hidden treasure that provides a world of opportunity to improve all aspects of life. In my opinion, one of the greatest challenges is the lack of knowledge by the public of our profession, so please help me spread the word about environmental health. Unfortunately, many environmental health professionals do not want to be in the media because it is not generally good news—but we need to change that dynamic. From Horton Hears a Who! by Dr. Seuss, “On the fifteenth of May, in the jungle of Nool, in the heat of the day, in the cool of the pool, he was splashing … enjoying the jungle’s great joys … when Horton the elephant heard a small noise.” Environmental health professionals need to sing out loud like the Whos, lose our fear, toot our horn, and shout to all, and not just to those in our sphere. Environmental health is public health, a fact lost on the general public, many politicians, and fellow scientists. As Dr. David Dyjack, executive director of the National Environmental Health Association (NEHA), states, “Environmental health is a contact sport.” As such, contact will be necessary to get our message out. When people think of how public health improves their lives, what comes to mind is what environmental health ensures—clean air, food, and water along with a safe and healthy place to live, work, and play. The early history of public health’s greatest successes came from environmental health, including improvements in the quality of drinking water, wastewater treatment, proper disposal of waste, reduction of vectors, and food safety. Environmental health measures such as the improvement of a community’s drinking water and wastewater assist an entire community, lowering the prevalence of disease. Environmental health provides the biggest return on investment; health education is a slower process since it involves changes on an individual level. The following information from the American Public Health Association’s (APHA) website (www.apha.org/about-apha/our-history) demonstrates how public health was spearheaded by environmental health professionals: • In 1895, APHA published the Standard Methods for the Examination of Water and Sewage. • In 1900, Dr. Walter Reed reported at the APHA annual meeting that mosquitoes carry yellow fever. • In 1905, APHA published the Standard Methods for the Examination of Milk. Environmental health’s success at improving housing conditions, sanitation, water quality, and food safety, as well as reducing vectorborne disease and pollution, has helped shift the burden of disease in this country from infectious disease to chronic disease. This change, due to the overall improvement in living conditions, shifted the focus of public health from disease prevention to the promotion of overall health, which led to many forgetting about the importance of environmental health. During tragic events such as the Flint water crisis, Zika outbreaks, food recalls, and the COVID-19 pandemic, the importance of environmental health becomes apparent. The COVID-19 pandemic showed that while humans have reduced infectious diseases, we are far from eliminating them. The pandemic demonstrated the values of our profession and we need to seize on this opportunity. Environmental health professionals utilized their scientific expertise and problem solving and communication skills to lessen the impact of COVID-19. As Winston Churchill worked to help form the United Nations after World War II, he famously said, “Never let a good crisis go to waste.” Environmental health is the heart of public health—we can perform the jobs public health or environmental science graduates do, but many public health or environmental science graduates cannot practice environmental health. I have observed numerous public health graduates who do not have enough coursework in the basic sciences and mathematics, especially since many public health programs evolved from community health or health behavior majors. In my experience, most environmental science programs lack the health aspect, so environmental health is the gold standard of public health education. Many of us learned about this wonderful field by a serendipitous event. Since many of us love science, which drew us to environmental health, we are interested in the facts. I joke with my students if they are doing inEnvironmental health is the heart of public health.
September 2022 • Journal of Environmental Health 7 dustrial hygiene monitoring for hexavalent chromium, they care only about what is the exposure. Even if hexavalent chromium had feelings, it would be irrelevant for environmental health; however, for others in public health, communication is their whole focus. An additional challenge for environmental health is there are more jobs than qualified people. Therefore, many environmental health professionals do not realize the need to spread the word. In the past year NEHA has seen a 5% increase in membership but with your help, we can improve. Another focus I have is to get a larger number of younger people not only into the profession but also more actively involved in NEHA. If there are not enough qualified graduates from National Environmental Health Science and Protection Accreditation Council-accredited schools, others will take our jobs. To spread the word about our wonderful field at Eastern Kentucky University, Dr. Jason Marion and I created a course titled Human Impact of the Essentials of Life, Air, and Water. If we called it Environmental Health, Air Pollution, and Water Pollution, we would not have had the success in drawing students from various majors. Even if the students do not become environmental health majors, they all learned the impact environmental health has on their lives, which helps to spread the message. In an eort to let people know environmental health is public health, I have started to refer to environmental health as environmental public health so people are reminded every time they see my email or talk with me. As our name has evolved from sanitarian to environmental health professional, NEHA’s marketing of our profession is evolving. Environmental health is a mile wide and an inch deep, causing challenges to define it in a condensed fashion. If we wait for others to spread the word, it will not happen. An example of how environmental health is overlooked is the NERD (Novel Emerging Respiratory Disease) Academy from the Centers for Disease Control and Prevention (CDC), which did not include an environmental health module. The CDC Nerd Academy (www.cdc.gov/scienceambassador/ nerdacademy/index.html) oers an innovative curriculum that includes eight standardsbased modules designed to teach middle and high school students about public health, epidemiology, and related careers. NEHA has discussed the development of a tool kit for educators to assist environmental health professionals get environmental health on the curriculum at middle and high schools. NEHA has started several marketing endeavors including the development of new mission and vison statements along with a new logo. The rebranding involves more than a new look—changes will include improvements to the website to increase the ease of use, greater utilization of social media, and other initiatives. I will work with NEHA members and sta to increase the visibility of our profession and to educate the public and the numerous professionals we work alongside that environmental health is public health. From How the Grinch Stole Christmas by Dr. Seuss: “‘That’s a noise,’ grinned the Grinch, ‘that I simply must hear!’ He paused, and the Grinch put a hand to his ear. And he did hear a sound rising over the snow. It started in low, then it started to grow. But this sound wasn’t sad!Why, this sound sounded glad! EveryWho down in Whoville, the tall and the small, was singing without any presents at all!” I am asking you to assist by becoming like the Whos— shouting from the roof tops words people must hear far and near, by talking to people outside our sphere, especially the younger ones, about this wonderful, magical career. firstname.lastname@example.org The NEHA Board of Directors recently approved an updated policy statement on the adoption of the Food and Drug Administration model Food Code. NEHA recommends complete adoption and implementation of the most recent version of the Food Code to promote the most current knowledge on food safety. Access the policy at www.neha.org/policy-statements. Did You Know? CP-FS/CCFS Join the growing ranks of professionals who have attained NEHA’s most in-demand credentials in food safety. Whether your focus is retail food service or food manufacturing and processing, NEHA’s Certified Professional—Food Safety (CP-FS) and Certified in Comprehensive Food Safety (CCFS) credentials demonstrate you went the extra mile to get specialized knowledge and training in food safety. Give yourself the edge that is quickly being recognized, required, and rewarded in the food industry. Learnmore at neha.org/professional-development/credentials. A credential today can improve all your tomorrows.
8 Volume 85 • Number 2 A D VANC EME N T O F T H E SCIENCE Introduction Polluted air is an important human health and environmental concern in many cities worldwide. Pollution in air originates from various natural sources (e.g., wildfires, volcanic eruptions); mobile sources (e.g., cars, trucks, o-road vehicles); and stationary sources (e.g., electric utilities, refineries, cement kilns). Particulate matter (PM) can be solid particles and liquid droplets and is one of six common air pollutants regulated by the U.S. Environmental Protection Agency (U.S. EPA) to protect human health. The other common air pollutants are ozone, sulfur dioxide, nitrogen dioxide, lead, and carbon monoxide. Most particle pollution forms in the atmosphere from chemical reactions involving sulfur dioxide, nitrogen oxides, and other chemicals (U.S. EPA, 2021). Direct source emitters of PM include roads, fields, industry, construction, fires, and volcanoes. Adverse human health outcomes of particulate pollution are well documented in the scientific literature. Fine PM, including particles <2.5 µm in diameter (PM2.5), can lodge deeply in the lungs and bloodstream of humans (Yeh et al., 1976). Inhaling large amounts of PM2.5 can cause heart or breathing problems, especially for children, older adults, and people with asthma or heart disease (Alhanti et al., 2016; Stafoggia et al., 2013). Using a global atmospheric chemistry model, Lelieveld et al. (2015) estimated that outdoor air pollution, mostly attributable to PM2.5, leads to approximately 3.3 million premature deaths per year worldwide, predominantly in Asia. In that assessment, energy used for heating and cooking had a major impact in India and China; trac and power generation were significant in much of the U.S.; and agricultural emissions contributed largely to PM2.5 in Europe, Russia, and East Asia. Currently, stationary fuel combustion accounts for approximately 45%, other stationary sources (primarily industrial) for 41%, o-road vehicles for 8%, and highway vehicles for 6% of direct PM2.5 emissions in the U.S. (U.S. EPA, 2021). Characterizing PM in air space is essential for assessing exposure hazard, although it is challenging in heavily populated urban complexes that are aected by numerous sources and processes that in turn influence pollutant fate and transport. Fine PM is highly mobile and its concentration at any given location reflects inputs from various sources (both internal and external to a study area) as well as weather patterns and chemical transformations. Dallas–Fort Worth is a large metropolitan area in the Southern U.S. that has experienced significant episodes of air pollution over the past several decades. The objective of this study was to identify and evaluate temporal patterns of PM2.5 concentrations at monitoring stations in Dallas, Abs t r ac t Spatial and temporal trends in air concentrations of particles <2.5 µm in diameter (PM2.5) were compiled, portrayed, and evaluated for three monitoring stations in North Central Texas over a 22year period. Two stations occupy the urban core of the Dallas–Fort Worth metropolitan area, and a third station lies at the northern edge of this area. Time series portrayed monthly averages of 1-hr PM2.5 concentrations for the entire period, as well as 1-hr PM2.5 concentrations for each hour in July 2021. Monthly time series showed a tendency for higher concentrations in summer months. Periodic upward spikes coincided with incursions of polluted outside air, especially Saharan dust. Overall, concentrations trended slightly downward over 22 years, despite a large population increase over that period. Hourly time series showed higher PM2.5 concentrations at midday, attributed to more anthropogenic activity, as well as periodic upward cycles lasting approximately three days, attributed to external dust events. Strong associations were measured between stations, especially for monthly averages, but also for continuous hourly measurements. Results suggest the importance of internal and external sources, regional transport and mixing, and a need for subhourly monitoring to better define polluted air space for exposure assessment. Long-Term Trends of Fine Particulate Matter in the Dallas–Fort Worth Metropolitan Area Paul F. Hudak, PhD Department of Geography and the Environment, University of North Texas
September 2022 • Journal of Environmental Health 9 Fort Worth, and Denton (a nearby city) and then quantify associations between temporal patterns over a 22-year period from January 2000–October 2021. Background PM in air often is quantified as PM2.5 or PM10, meaning particles <2.5 µm or <10 µm, respectively. These particles include a mixture of substances in five main categories: sulfate, nitrate, elemental carbon, organic carbon, and crustal material (U.S. EPA, 2021). Sea salt is also an important form of PM, especially in coastal regions. Organic PM includes hundreds of compounds with a wide range of chemical properties (Polidori et al., 2006). Based on data from Thurston et al. (2011) from >200 sites across the U.S., primary emission sources for PM2.5 include the metals industry (lead, zinc), crustal and soil particles (calcium, silicon), motor vehicle trac (elemental carbon, nitrogen dioxide), the steel industry (iron, manganese), coal combustion (arsenic, selenium), oil combustion (vanadium, nickel), salt particles (sodium, chloride), and biomass burning (potassium). Dust and wildfires can also aect pollutant levels over large areas. Kaulfus et al. (2017) studied the impact of wildland fires on particulate air quality in the U.S and reported that smoke was most frequently found over the Great Plains and Western states during the summer months. Smoke from wildfires was involved in approximately 20% of air pollution events in the continental U.S., with concentrations above federal standards. While smoke episodes tended to be more frequent in summer, occasionally, southerly winds in spring transported smoke from fires in Central America into the Southern U.S. (Kaulfus et al., 2017). Numerous studies have documented associations between long-term exposure to PM and adverse health outcomes, especially cardiopulmonary disease and mortality (Anderson et al., 2012; Peng et al., 2009; Pope et al., 2019; Scheers et al., 2015). PM harms cardiovascular and cerebrovascular systems via inflammation, coagulation activation, and translocation into systemic circulation (Anderson et al., 2012). Controlled exposure trials have shown that inhaling air polluted with PM increases diastolic blood pressure, likely by instigating acute autonomic imbalance (Brook et al., 2009). Inhaled PM also causes oxidative stress and inflammation that contributes to respiratory morbidity (Anderson et al., 2012). PM was significantly associated with death from all causes—and from cardiovascular and respiratory illnesses—in 20 large U.S. cities from 1987 to 1994 (Samet et al., 2000). Similarly, Liu et al. (2019) compiled daily mortality and air pollution data from 652 cities in 24 countries and regions and found independent associations between short-term exposure to PM and total, cardiovascular, and respiratory mortality. In China, short-term increases in PM2.5 concentrations in 272 cities were significantly associated with increased mortality from all nonaccidental causes, as well as from cardiovascular disease, hypertension, coronary heart disease, stroke, respiratory disease, and chronic obstructive pulmonary disease (Chen et al., 2017). In a compilation of cohort studies over the past 25 years, Pope et al. (2020) found substantial evidence of adverse associations between fine PM and all-cause, cardiopulmonary, and lung cancer mortality. The Clean Air Act of 1970, subsequent amendments, and major technological advances reflect increased awareness and concern over air pollution in the U.S. Consequently, air quality across the U.S. has improved markedly since the 1970s (Sullivan et a l., 2018). Pollution thresholds have dropped: current PM2.5 design values in Texas and much of the U.S. are 35 µg/m3 for 24 hr and 12 µg/m3 for 1 year (Texas Commission on Environmental Quality [TCEQ], 2021). In the U.S. between 2000 and 2020, gross domestic product, vehicle miles traveled, and population all increased, yet direct PM2.5 emissions dropped by 38%, annual PM2.5 concentrations decreased by 41%, and 24-hr PM2.5 concentrations decreased by 30% over that period (U.S. EPA, 2021). Texas has experienced more modest but major improvements in air quality over the past two decades. From 2002–2020, annual PM2.5 concentrations decreased by 24% (34 µg/m3 to 29 µg/m3) and 24-hr PM 2.5 concentrations dropped by 15% (14.3 µg/m3 to 10.8 µg/m3) (TCEQ, 2021). Statewide point source emissions of PM2.5 dropped from 34,000 tons in 2014 to 30,000 tons in 2019 (TCEQ, 2021). Although air quality has improved in the U.S. and current standards are met in many places, some urban areas remain problematic. Research shows, however, that respiratory and cardiovascular problems can occur at outdoor pollutant levels that are well below standards set by the U.S. EPA and World Health Organization (Curtis et al., 2006). Moreover, Thurston et al. (2016) evaluated a cohort of 517,041 adults over an exposure period from 2000–2009 in six U.S. states and metropolitan areas; they found that long-term exposure to PM2.5 was associated with increased risk of mortality from all causes and from cardiovascular disease, despite experiencing lower (i.e., post-2000) air pollution exposure levels. Kettunen et al. (2007) studied associations between daily levels of air pollutants and deaths caused by stroke among older adults in Helsinki, Finland, which has relatively low air pollution. They found that PM2.5 was associated with increased risk of fatal stroke during the warm season, possibly due to seasonal dierences in exposure or pollutant content. Another study in rural British Columbia, where mean annual PM2.5 concentrations ranged from only 3.1 µg/m3 to 7.4 µg/m3, found that PM2.5 still had an important mortality burden among adults (Elliott & Copes, 2011). Studies also show that reducing air pollution leads to positive health outcomes. Pope et al. (2009) determined that reduced exposure to fine particulate air pollution improved life expectancy in U.S. cities in the 1980s and 1990s. In a study of six U.S. cities, cardiovascular and lung cancer mortality were each positively associated with ambient PM2.5 concentrations and reduced PM2.5 concentrations were associated with reduced mortality risk (Laden et al., 2006). Bo et al. (2019) found that reduced PM2.5 exposure was associated with decreased incidence of hypertension and cardiovascular disease. Polluted air also damages plants and building materials. Fine particulates can travel long distances and deposit on soil, vegetation, or surface water, thereby depleting nutrients or changing nutrient balances and damaging sensitive ecosystems (U.S. EPA, 2021). Study Area The study area is located within the Cross Timbers and Texas Blackland Prairies ecore-
10 Volume 85 • Number 2 A D VANC EME N T O F T H E SCIENCE gions (Gri th et al., 2007; Figure 1). To the west, the Cross Timbers features forested hills, prairies, and stream valleys with sandy to clayey soil. Although the study area is heavily urbanized, natural vegetation in the Cross Timbers includes little bluestem grassland with scattered blackjack oak and post oak trees. Fine textured clayey soils and prairie grasses occupy the Texas Blackland Prairies. Predominant grasses include little bluestem, big bluestem, yellow Indiangrass, and switchgrass. Pasture and forage production for livestock is common, though large areas of the region have been converted to urban and industrial uses (Gri th et al., 2007). Dallas–Fort Worth has a humid subtropical climate characterized by long, hot summers and a wide annual temperature range; precipitation also varies considerably, ranging from <50 cm to >130 cm per year (National Weather Service, n.d.). Winds are predominantly southeasterly throughout late spring, summer, and early fall. Wind directions are more variable in late fall, winter, and early spring, moving in from all directions, especially from the northwest and southeast. The study area includes 10 counties, as identified by the Texas Commission on Environmental Quality (TCEQ, 2021) in its State Implementation Plan to satisfy air quality standards and requirements of the Federal Clean Air Act and subsequent amendments (Figure 1). The population of the study area has steadily increased over the past several decades and currently is approximately 7.5 million people (Table 1). The four most populated counties (Dallas, Tarrant, Collin, and Denton) account for nearly 90% of the total population and automobile travel in the area. These four counties, especially Dallas and Tarrant, constitute the urban core of the Dallas–Fort Worth metropolitan area. Over the past two decades, daily vehicle miles traveled also have increased over the study area and currently total more than 180 million miles. On- and o-road mobile and area sources are the main sources of air pollution in North Central Texas (TCEQ, 2015). Mobile sources account for most of the area’s carbon monoxide, nitrogen oxides, and lead emissions. Area sources (i.e., facilities)—including printing, coating, oil/gas production, and oil/gas combustion—contribute most of the PM and volatile organic compounds. Point sources—including electric generators, cement kilns, and oil/gas operations— account for most sulfur dioxide emissions. According to TCEQ (2015), external pollutants including PM2.5 also enter the study area, including periodic haze from the eastern U.S. (typically from May through September); smoke from Mexico and Central America (typically in late spring); Saharan dust (typically in summer months); Great Plains dust (typically in late spring); and smoke from fires in Texas. Methods We compiled monthly averages of 1-hr PM2.5 measurements from January 2000–October 2021 for three continuous ambient monitoring stations (CAMS): CAMS56 in Denton, CAMS310 in Fort Worth, and CAMS401 in Dallas (Table 2 and Figure 1). Denton, Fort Worth, and Dallas are the largest cities in Denton, Tarrant, and Dallas counties, respectively (Figure 1). Additionally, we compiled 1-hr PM2.5 measurements for each hour in July 2021 for each station. Data were obtained from TCEQ (2021), tabulated, and portrayed in time series. Descriptive statistics were computed for each station and correlations were computed between pairs of stations. Spearman correlations were computed, as the data are non-normally distributed. CAMS301 (Fort Worth) and CAMS401 (Dallas) occupy heavily developed urban areas in the core of the Dallas–Fort Worth metropolitan area. CAMS56 (Denton) lies at County Populations and Daily Vehicle Miles Traveled County Population 1 Daily Vehicle Miles Traveled 2 2005 2012 2019 2005 2012 2019 Dallas 2,250,830 2,455,930 2,635,516 66,395,655 62,749,078 68,081,264 Tarrant 1,612,048 1,882,205 2,102,515 44,070,118 45,132,068 48,693,457 Collin 647,187 835,230 1,034,730 14,351,788 16,115,346 21,117,653 Denton 553,669 707,892 887,207 11,571,039 13,242,099 17,706,743 Ellis 129,955 153,739 184,826 4,942,796 5,150,294 6,334,734 Johnson 140,692 153,415 175,817 3,890,137 3,505,595 4,551,164 Parker 101,891 119,482 142,878 3,506,343 3,585,704 4,698,133 Kaufman 87,388 106,553 136,154 4,162,626 3,717,978 4,680,232 Rockwall 60,349 82,710 104,915 1,692,083 1,876,504 2,574,184 Wise 55,613 60,424 69,984 2,657,017 2,459,472 2,715,654 Total 5,639,622 6,557,580 7,474,542 157,239,602 157,534,138 181,153,218 1 Texas Department of Transportation, 2022. 2 U.S. Census Bureau, 2021. TABLE 1
September 2022 • Journal of Environmental Health 11 the western edge of Denton in a small airport surrounded by open fields, rangeland, industrial, and sparse suburban residential land use and cover. Additionally, areas south and west of CAMS56 (Denton) have produced large amounts of natural gas from the underlying Barnett Shale over the past 15 years. The three monitoring stations are located in open areas to reduce obstruction from trees, buildings, and other obstacles (TCEQ, 2021). TCEQ (2021) maintains quality control measures to ensure proper operation of monitoring equipment, adhering to federal sampling and analytical requirements. As PM2.5 pollution is complex, its composition is not well known throughout the entire study area. CAMS401 (Dallas), however, has speciation capability; in 2019, PM2.5 sampled at CAMS401 consisted of (from highest to lowest): organic carbon, sulfate, crustal material, nitrate, elemental carbon, and sea salt (U.S. EPA, 2021). By comparison, sulfate was the predominant constituent in 2001, followed by organic carbon, nitrate, crustal material, elemental carbon, and sea salt. Overall, graphs of annual percentage contributions from 2001 to 2019 show decreases in sulfate, modest increases in organic carbon (but steady since 2009), slight increases in crustal material (though highly variable), slight decreases in nitrate, and relatively steady percentages of elemental carbon and sea salt (U.S. EPA, 2021). Altogether, annual PM2.5 at CAMS401 (Dallas) decreased from 7.4 µg/m3 in 2001 to 5.8 µg/m3 in 2019 but was highly variable over that period (U.S. EPA, 2021). Results and Discussion The long-term time series for CAMS56 (Denton) shows considerable fluctuation between months, especially early in the series (Figure 2). Typically, higher PM2.5 concentrations occurred in summer months, with lower levels observed in winter months. This pattern reflects persistent winds from the southeast that transport polluted air from other parts of Dallas–Fort Worth as well as other urban complexes to the southeast of the study area during the summer. Saharan dust events and wildfires also tend to aect the study area more in late spring and summer than in other months. Overall, monthly PM2.5 concentrations ranged from 3.8 µg/m3 to 16.5 µg/m3 and averaged 8.4 µg/m3 at CAMS56 (Denton). Concentrations trended slightly downward over the 22-year record (Figure 2). The monthly PM2.5 time series for CAMS56 (Denton) shows several upward spikes that coincide with pollution events originating outside the study area (Figure 2). For example, fires in Mexico and Central America aected the study area in May 2003. Saharan dust storms entered the study area during the summers of 2013, 2014, 2015, 2018, 2020, and 2021, and likely earlier in the time series. Crustal material (dust) is highly variable as a percentage PM2.5 and was markedly higher in 2018 at CAMS401 (Dallas) (U.S. EPA, 2021). Typically, these dust storms elevate PM2.5 levels in the study area for approximately three consecutive days, thus significantly aecting monthly averages. Monthly time series for CAMS301 (Fort Worth) and CAMS401 (Dallas) shows similar patterns as CAMS56 (Denton). For example, Continuous Ambient Monitoring Stations (CAMS) Monitoring Station Identification # Name/ Location Latitude (Degrees) Longitude (Degrees) Elevation (m) CAMS56 Denton Airport South 33.2190759 -97.1962841 183.0 CAMS310 Fort Worth Haws Athletic Center 32.7591946 -97.3423075 165.0 CAMS401 Dallas Hinton 32.8200660 -96.8601230 126.5 TABLE 2 Study Area With County Boundaries, Ecoregion Boundaries, and Monitoring Stations Note. Ecoregion boundaries are indicated by bold lines. Monitoring stations are indicated by +. CAMS = continuous ambient monitoring station. FIGURE 1
12 Volume 85 • Number 2 A D VANC EME N T O F T H E SCIENCE peaks and valleys in the time series tend to coincide among the three stations. Typically, concentrations were slightly higher for CAMS301 (Fort Worth) and CAMS401 (Dallas) compared with CAMS56 (Denton), probably reflecting more emissions from sources closer to CAMS301 (Fort Worth) and CAMS401 (Dallas). Overall, monthly PM2.5 levels ranged from 5.2 µg/m3 to 16.7 µg/m3 and averaged 9.6 µg/m3 at CAMS301 (Fort Worth). At CAMS401 (Dallas), PM2.5 concentrations ranged from 4.7 µg/m3 to 18.3 µg/m3 and averaged 9.7 µg/m3. Monthly variability of 1-hr PM2.5, expressed as standard deviation, ranged from 2.1 µg/ m3 to 14 µg/m3 and averaged 5.1 µg/m3 at CAMS56 (Denton) (Figure 3). Typically, higher standard deviations were observed in spring and fall, likely caused by more variable temperature, wind, and rain patterns in those seasons compared with summer, which involves consistently high temperatures, southeasterly winds, and sparse rainfall. Also in spring and fall, wind blows into the study area from various directions, which brings in air with variable PM2.5 characteristics. This pattern is in contrast to the summer, which brings in frequently polluted air from the southeast. Overall, the standard deviation of 1-hr PM2.5 concentrations, compiled by month, trended slightly downward for CAMS56 (Denton) over 22 years. CAMS301 (Fort Worth) showed slightly higher standard deviations, averaging 5.8 µg/ m3, across the long-term time series (Figure 3). A large upward spike in standard deviation, to 25 µg/m3, in late 2012 was observed for CAMS301 (Fort Worth), but not for the other two monitoring stations. That spike likely reflects a localized event that mainly affected the Fort Worth monitoring station, as opposed to incursion of polluted air originating from outside the study area, which would be expected to affect all three stations. Summer months tended to have lower standard deviations than other months in 1-hr PM2.5 at CAMS401 (Fort Worth), which was similar to CAMS56 (Denton). Overall, standard deviation was steady across the 22-year record, reaching a low of 2.2 µg/m3 for CAMS401 (Fort Worth). Other than the spike mentioned previously, CAMS401 (Dallas) showed similar patterns in standard deviation to CAMS301 (Fort Worth), ranging from 3.5 µg/m3 to 13.5 µg/m3 and averaging 5.9 µg/m3. Consistent with observed patterns in the 3-monthly time series, Spearman correlations were high between pairs of monitoring stations: CAMS56 (Denton) and CAMS301 (Fort Worth), .91; CAMS56 (Denton) and CAMS401 (Dallas), .84; and CAMS301 (Fort Worth) and CAMS401 (Dallas), .80. All p-values were <.00001, which indicated a high level of statistical significance. A slightly higher correlation between CAMS56 (Denton) and CAMS301 (Fort Worth) reflects prevailing southeasterly winds in summer months, which promotes movement and mixing of air between those monitoring stations. Periodic northwesterly winds in cooler months also promote movement and mixMonthly Average of 1-Hour PM2.5 Concentrations From January 2000– September 2021 at CAMS56 (Top), CAMS310 (Middle), and CAMS401 (Bottom) Note. Each interval on the x-axis represents 12 months. All concentrations are measured in µg/m3. CAMS = continuous ambient monitoring station; PM = particulate matter. FIGURE 2
September 2022 • Journal of Environmental Health 13 ing of air between CAMS56 (Denton) and CAMS301 (Fort Worth). The overall similarity in time series reflects transport and mixing of air influenced by different sources within the metropolitan area, as well as outside events that can affect all three monitoring stations. Various pollution sources, operating over large areas, affect PM2.5 concentrations observed at each monitoring station. Interestingly, the data show little impact of the COVID19 pandemic on PM2.5 concentrations in the study area. At many U.S. locations, the pandemic contributed to improved air quality, especially in spring 2020 (U.S. EPA, 2021). In this study, PM2.5 concentrations were similar in spring 2020 and spring 2021—and concentrations were actually higher in summer 2020 than in the prepandemic summer 2019 (Figure 2). When viewed at an hourly scale, for each hour in July 2021, CAMS56 (Denton) produced PM2.5 concentrations that ranged from 0 µg/m3 to 48 µg/m3 and averaged 12.0 µg/m3 (Figure 4). The hourly time series shows a daily cycle, with a tendency for highest PM2.5 concentrations around midday and lowest concentrations around midnight. More anthropogenic activity in the daytime leads to more PM and other air pollutants. Figure 4 also reveals upward pulses in PM2.5 lasting approximately three days, likely caused by polluted air from external sources moving into the study area. Specifically, multiple Saharan dust storms entered the study area in mid- to late July 2021. Several short-term, hourly spikes in PM2.5 also appear in the hourly time series (Figure 4). These hourly spikes reflect more localized events that affected the monitoring station. No weekend pattern was evident for CAMS56 (Denton) in July 2021. Less commuting might result in modest traffic reduction on weekends; however, as noted, on-road mobile sources are not the main component of PM in the study area. The July 2021 hourly time series for CAMS56 (Denton) shows an overall increase over time as midsummer approached. Patterns previously noted also appear in the July 2021 hourly time series for CAMS301 (Fort Worth) and CAMS401 (Dallas). Hourly PM2.5 concentrations ranged from 0 µg/m3 to 98.5 µg/m3 and averaged 13.2 µg/m3 at CAMS301 (Fort Worth). At CAMS401 (Dallas), hourly PM2.5 concentrations ranged from 1 µg/m3 to 51 µg/m3 and averaged 12.1 µg/m3. CAMS301 (Fort Worth) showed fewer hourly upward spikes than the other two monitoring stations; however, one prominent spike occurred at approximately 96 hr at all three stations. That peak coincided with the evening of July 4, when fireworks likely elevated PM in the study area. When compared with the monthly series, slightly lower (though statistically significant) Spearman correlations were computed for the hourly series: CAMS56 (Denton) and CAMS301 (Fort Worth), .72; CAMS56 (Denton) and CAMS401 (Dallas), .76; and CAMS301 (Fort Worth) and CAMS401 (Dallas), .78. Each p-value was <.00001, which again indicates a high level of statistical significance. Peaks and valleys tended to coincide between hourly graphs in Figure 4, but coincided more weakly between peaks and valleys in the monthly graphs in Figure 2. Hourly fluctuations help characterize air quality but tended to smooth out when aggregated monthly. Even at an hourly scale, however, the three time series are rather similar. While pollution from a nearby source might affect one monitoring station more than others, it often impacts others (at least marginally) because fine PM is highly mobile, even over short time frames. This observation points to a need for subhourly records to best characterize polluted air in urban settings such as Dallas–Fort Worth. High correlations in PM2.5 concentrations among the monitoring stations observed in this study are consistent with previous studies of PM2.5 in other metropolitan areas. PM2.5 tends to stay suspended longer, leading to increased mixing and more homogeneous disMonthly Standard Deviation of 1-Hour PM2.5 Concentrations From January 2000–September 2021 at CAMS56 (Top), CAMS310 (Middle), and CAMS401 (Bottom) Note. Each interval on the x-axis represents 12 months. All concentrations are measured in µg/m3. CAMS = continuous ambient monitoring station; PM = particulate matter. FIGURE 3
14 Volume 85 • Number 2 tributions than coarser particles (Wilson et al., 2005). For example, DeGaetano and Doherty (2004) found high correlations in 1-hr PM2.5 in New York City. Several others have observed high correlations in 24-hr PM2.5, for example, in Philadelphia, Pennsylvania (Burton et al., 1996; Wilson & Suh, 1997); St. Louis, Missouri (Wilson & Suh, 1997); and New York City (Bari et al., 2003). Moreover, TCEQ (2015) observed moderate correlations in 24-hr PM2.5 between 2011 and 2013 at monitors in Dallas, Arlington, and Fort Worth. At a weekly scale, Ye et al. (2003) calculated high correlations in PM2.5 between two sampling stations in Shanghai, China, over a 1-year period. Longer averaging typically produces stronger associations. Thus, Bari et al. (2003) found much higher correlations for 24-hr PM2.5 than for 1-hr PM2.5 in New York City. Other studies, however, have found significant variability in PM2.5 concentrations measured in urban complexes. Pinto et al. (2004) studied 24-hr PM2.5 at 27 urban areas across the U.S. They found high correlations between site pairs and spatial uniformity in concentration fields in the Southeastern U.S., but significant spatial variation in other regions, especially in the Western U.S. Furthermore, highly correlated pairs of sites did not necessarily have similar concentrations. Goswami et al. (2002) found significant spatial variability in PM2.5 at 40 outdoor sites in Seattle, Washington. Elevation and distance from major roads were found to be significant in predicting PM concentrations. Results outlined in this article have important public health policy implications. While time series analyses based on hourly or longer averages can appear similar and produce high correlations, they do not indicate similar personal exposure across an urban complex (Wilson et al., 2005). Finer temporal resolution is necessary to better assess actual exposure. For example, exposure to a constant concentration of PM2.5 (or other pollutant) over a 1-hr period is different from being exposed to an average concentration (with highs and lows) of PM2.5 over a 1-hr period. The chemical composition of PM is also important in assessing exposure hazard and related health outcomes (Dergham et al., 2015). Conclusion The objective of this study was to evaluate long-term trends in PM2.5 concentrations at monitoring stations in the core and periphery of the Dallas–Fort Worth metropolitan area from January 2000–October 2021. Time series of hourly PM2.5, averaged by month, showed typically higher concentrations in summer and lower concentrations in winter, reflecting steady southeasterly winds and more external sources impacting the study area in summer. External events such as dust storms caused periodic upward spikes in PM2.5, especially in summer months. Overall, PM2.5 trended slightly downward over the 22-year period. Hourly data for July A D VANC EME N T O F T H E SCIENCE One-Hour PM2.5 Concentrations in July 2021 at CAMS56 (Top), CAMS310 (Middle), and CAMS401 (Bottom) Note. Each interval on the x-axis represents 24 hr. Furthermore, on the x-axis, weekends coincide with 48–96, 216–264, 384–432, and 552–600 hr. All concentrations are measured in µg/m3. CAMS = continuous ambient monitoring station; PM = particulate matter. FIGURE 4
September 2022 • Journal of Environmental Health 15 2021 showed a tendency for higher concentrations at midday and lower concentrations at midnight, suggesting more pollution-generating activity in the daytime. Hourly series also showed that upward pulses last approximately three days, likely due to external dust storms entering the study area. Upward concentration spikes reflected sources both internal and external to the study area. High degrees of associations were observed between pairs of monitoring stations, especially for the monthly time series, but also for the hourly series, which suggests regional transport and mixing, as well as a need for finer temporal resolution to characterize air quality and exposure more accurately in the study area. Corresponding Author: Paul F. Hudak, Professor, Department of Geography and the Environment, University of North Texas, 1155 Union Circle #305279, Denton, TX 762035017. Email: email@example.com. 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