Can DIY air monitoring save DFW air?

Air quality watchdog groups are increasingly using handheld air monitors to collect their own air quality data. Photo by Julie Thibodeaux.

March 10, 2021

Nine months after pediatrician Laura Hunt moved to Midlothian in 2014, her then four-year-old daughter developed an alarming respiratory condition.

“She started coughing, just a bad, wet cough and I initially was like oh, she has a virus. And then oh she has a lingering cough after the virus, but I mean, she basically coughed badly every day for at least 18 months straight,” Hunt recalls.

Frustrated and distraught by her child’s suffering and after trying everything to alleviate the condition, she took her to National Jewish Hospital in Denver for testing, which helped establish a course of treatment but was inconclusive as to the cause.

Midlothian Cement Capitol signMidlothian sign brags about the town's three cement kiln operations. Photo by J.G. Domke.

It was then that Hunt couldn't help but wonder if her daughter’s respiratory ailment, and later that of her older son, had something to do with the emissions belching from the smokestacks of the three cement kiln operations in Midlothian, a town that boasts that it’s the cement capitol of Texas, just 30 miles south of downtown Dallas.

“Anyone that lives in Midlothian knows of the existence of the cement plants, because they’re so larger than life. You see them all the time ... but I didn't really become concerned about them until my daughter got sick,” Hunt says.

Today Hunt is the leader of a handful of concerned Midlothian residents, known as Midlothian Breathe. The group formed in 2019 to keep a watch on the local sources of pollution to find out if Texas’ environmental regulatory agency is indeed doing its job of protecting human health.

When the Texas Commission on Environmental Quality signaled late in 2020 that it would grant a permit to one of the Midlothian cement kilns to increase its emissions and allow it to burn a greater percentage of petroleum coke in its cement clinker operation despite local residents’ concerns, the group felt compelled to ramp up their effort to take matters into their own hands.

Last fall, they joined other environmental watchdogs in North Texas, like Downwinders at Risk and Liveable Arlington, by adopting a plan to purchase their own air quality sensors, which they hope to install throughout their neighborhoods.

Midlothian Breathe's goal is to collect the data they need to determine if TCEQ and the industries that produce air emissions are being straight with them when it comes to matters about the environment that may directly affect their health.

Holcim cement plant in MidlothianLast year, TCEQ signaled it would grant a permit to Holcim cement plant in Midlothian to increase its emissions despite pushback from citizens. Photo by J.G. Domke.

This push is made possible by the recent advent of low-cost air quality sensors that bring air quality monitoring to anyone with about $300 to spend on the wi-fi enabled devices that track air quality changes and record the data they collect. Midlothian Breathe has purchased one so far and seeks to raise funds to purchase more.


The question remains, though, whether the low-cost sensors available today are any match for the sparse industry-grade sensors already set up by the EPA in the Dallas-Fort Worth area and in Midlothian itself.

Chris Klaus, a senior program manager for the North Central Texas Council of Governments who oversees the region’s compliance with the EPA’s air quality standards, says a qualified maybe.

“There seems to be a growing interest of a lot of local governments and others that are trying to supplement the regulatory monitors with more cost-effective, more localized monitoring, to just monitor the air and see how things are actually occurring, because they know it’s hard to defend, or it’s hard to argue, what may be there, when you don't have the monitoring,” Klaus says. “Similar to California, the City of Dallas and the City of Plano are cities that are working on this.”

Klaus says he’s encouraged by any action that results in more people becoming involved in civic matters but questions if the data collected by the citizen-scientist type of air quality sensors offers any usable insight into the quality of the air we breathe. 

Liveable Arlington air monitoring workshopKatheryn Rogers of Liveable Arlington learns how to use an air monitor during a Downwinders at Risk workshop hosted by Liveable Arlington in January 2020. Photo by Julie Thibodeaux.

Air quality monitoring, he says, is a science unto itself, with a wide range of protocols and standards regarding the placement and positioning of sensors and accounting for variations in atmospheric conditions to arrive at an accurate generalization of air quality at a given location at any specific span of time. 

Without those standards in place, the data lacks the scientific rigor needed for a fair assessment of general air quality, measuring only what’s in the air in a very specific spot, which can be unduly alarming if a neighbor upwind decides it’s a nice day to fire up the barbecue grill.

“If you have a particle monitor, how would it know the difference if something was from a dirt road, a vacuum cleaner or a street sweeper — it’s still particles in the air?” he says, pointing out another limitation of the sensors that only measure so-called particulate matter and not the compounds such as nitrous oxide that result in ozone pollution — the major culprit for the Dallas-Fort Worth area’s chronic noncompliance with the minimum EPA standard for healthy air.

Liveable Arlington air monitoring workshopKris Yowtak practices taking an air quality reading in downtown Arlington during a workshop hosted by Liveable Arlington in January 2020. Photo by Julie Thibodeaux. 

What could enhance the data collected from citizen scientists, Klaus says, is if the data is correlated to public health information, such as when an increase in a network of citizen air quality monitors’ readings correlate with an increase of nosebleeds or asthma symptoms at local elementary schools, or cases of emergency room visits for respiratory distress at a local hospital. A complete assessment of broad health trends in the Dallas-Fort Worth area combined with air quality data would also help prioritize regional environmental goals among decision makers in North Central Texas because too often those goals are just paperwork with no apparent effect on people in their daily lives. A documented increase in emergency room visits on bad air quality days could really drive home the urgency of the matter.

Klaus says NCTCOG has established a committee to look into these issues. Started last year to make headway on collecting local health data, the committee is now establishing contacts in cities and counties in North Central Texas and compiling the information the contacts have to share. But their work has only just begun.

“More monitoring? I’d never discourage that, but we want good, reliable monitoring and then couple that with strong health data that I can get from reliable sources,” he says.

Dr. David Lary at the 2018 GSDFW AwardsDr. David Lary accepts an award for his work on a regional air monitoring network at the 2018 Green Source DFW Awards. Photo by Andrea Ridout.


Dr. David Lary is a professor at UT Dallas and an expert on atmospheric chemistry. He agrees that care needs to be taken when using off-the-shelf consumer-grade air quality monitors. He’s tested low-cost sensors and has sometimes found diverse ratings between them when they are positioned side by side, or even when one sensor in a sequence reads the air contents already measured by another.

The minimum cost for a reference system that can give reliable data for air quality is typically between $15,000 and $20,000, he estimates, which is often beyond the budget of nonprofits and groups of concerned citizens — and even most small municipalities.

But Lary and his students are working on using artificial intelligence to calibrate the low-cost sensors against reference sensors so that low-cost sensors can provide more useful data and create the possibility of charting the changes in air emissions from neighborhood to neighborhood.

Companion monitor used during a Liveable Arlington workshop to assess weather conditions. Photo by Julie Thibodeaux.

Lary says that the readings of low-cost air quality sensors are affected by the ambient conditions such as the air pressure, humidity and temperature, which high-end systems account for. By networking low-cost sensors with high-end sensors in an area, the data can be corrected using machine learning algorithms that essentially learn the kinks and peculiarities of each low-cost sensor, which effectively calibrates the low-cost sensors to bring their data up to standard.

“What is a bit different about what we're doing is, we will calibrate our low-cost sensors against the reference sensor. So basically, what that involves is the high-end reference sensor will be co-located with the cheaper sensor for an extended period, typically about six months, where measurements will be typically gathered every one second, or every two to three seconds depending on which sensor we're talking about. And then all of that data, which will be hundreds of thousands of records, will be used to train a multivariate machine learning model, so that the cheapest sensors can really do a pretty good job of reproducing the observations from the reference sensor,” Lary explains.

Lary invites citizen scientists and community groups who are concerned about air quality to join up with the efforts of his students’ research to build an increasingly reliable network of affordable air quality monitoring stations. His hope is that he will soon have a resource available where participants can purchase equipment for a nominal fee to provide the kind of data that can be used by neighborhood watch groups, municipalities or even just concerned individuals who want to improve air quality by pinpointing emissions sources that need to be addressed.

Lary stresses that he and his team remain neutral on the politics of environmental protection; they simply want to create a tool for measuring the quality of the air in our communities. He believes that when more people have access to the information that can affect their health, policy makers and corporations will naturally make their decisions in a more transparent process that’s informed by the relevant data and consequently holds up to more intensive scrutiny by those affected by air quality policies.

Shared Air Network mounted monitorA mounted monitor installed for the Shared Air DFW network, spearheaded by Downwinders at Risk. Courtesy of Misti O'Quinn.

For this reason, he’s excited to see groups such as Midlothian Breathe take interest in trying to see what’s in the air, and therefore in our lungs and bloodstream. His assistance has been sought after by the Dallas-based Downwinders at Risk, an environmental group deploying Lary’s tech approach to monitoring air quality in Joppa, which is another community south of Dallas that’s going up against its own air polluters, including an asphalt batch plant, an asphalt shingle plant, a railyard and a concrete production facility.

“We are not partisan in anything because our main goal is societal benefit, and also the training of the students that come through the university,” Lary says. “Our role in that project is to build and calibrate low-cost sensors — to calibrate them against reference sensors — that can then be deployed across neighborhoods.”

Hunt says she understands the limitations of the low-cost sensors but she still sees value in their readings, especially when a group of sensors in a neighborhood simultaneously shows elevated readings that point to something going on upwind. Lary concurs that varying upwind emissions lead to “spatially and temporarily varying concentrations” of airborne particulate matter that can vary wildly across a city, from region to region and even neighborhood to neighborhood, which makes monitoring on the microscale essential to getting a clearer picture of what we’re all breathing.

“When you're trying to characterize the air quality for a neighborhood, a zip code, census tract, a town or all of DFW, you have so many micro environments going on there. And so the measurements you might see at a reference sensor, say that the EPA is reporting, if it’s 10 miles, 30 miles away from you, it may be very different from the local situation,” Lary says. “Our bigger vision, in fact, is to bring together the health outcome, like mortality, school absenteeism — a whole range of holistic societal measures — and compare them to environmental conditions, because there could be an elephant in the room that we’re just missing, just because we’re not bringing together the appropriate data.”

Holcim looms over Mockingbird Nature Trail in Midlothian.The Holcim cement plant smokestacks can be seen from the Mockingbird Nature Trail in Midlothian. Photo by J.G. Domke.


Both Hunt and Lary argue that air quality is of major importance to our everyday health and yet very low on the priority list as a society. It’s just too easy to dismiss an invisible threat like microscopic particles of air pollution. And although asthma may be more directly seen as a consequence of breathing polluted air, many health conditions linked to the quality of the air we breathe can take decades to manifest symptoms.

“If you look, for example, at the increase in Alzheimer’s and so many other conditions, it seems these particles can even get across the blood-brain barrier and cause cognitive decline. So, I don't think any of us want this — this is in all of our interest,” Lary says.

Both Hunt and Lary argue that air quality is of major importance to our everyday health and yet very low on the priority list as a society.

That’s why Hunt and Midlothian Breathe want to arm neighborhoods downwind of the cement kilns in Midlothian with air quality monitors, to start a conversation if nothing else. 

TCEQ air monitoring mapTCEQ map of air monitors in the DFW area. See interactive version. Courtesy of TCEQ.

For decades, we’ve increasingly become aware that our intake of high-cholesterol foods or sugar or alcohol leads to poor health but most people rarely if ever think about the 20,000 breaths of air we inhale every day — that’s 400 million breaths by the time we’re 50 years old.

Each breath we take if laced with tiny particles of heavy metals and other toxic compounds can elevate our risk of stroke, heart disease, diabetes, cancer, pregnancy complications and of course, asthma and COPD — all of which can lead to earlier death. The smaller those particles from smokestacks are, the more easily they can get past our body’s defenses and enter our bloodstream, reaching all our vital organs and our brain itself.

Lary says the measures we’ve taken to mitigate the death toll from COVID-19 show what we can do when we understand what the stakes are. But everyday air pollution continues to be a mere afterthought for most.

“Right now, we're all painfully and acutely aware of COVID-19 and the impact that that's having. We’re around half a million deaths. And the number of deaths every year that the World Health Organization estimates to be due to air quality globally is seven million. So with the terrible impact that COVID has had, it’s not close to what air quality is doing every year,” Lary says.

“Right now, we're all painfully and acutely aware of COVID-19 and the impact that that's having. We’re around half a million deaths. And the number of deaths every year that the World Health Organization estimates to be due to air quality globally is seven million. So with the terrible impact that COVID has had, it’s not close to what air quality is doing every year,” Lary says.

Hunt says she wants the network of air quality sensors that Midlothian Breathe sets up throughout the city to inspire residents to participate in the policies that affect their air and ultimately their health. 

Now when a cement kiln or a steel mill, or any other industry applies to the TCEQ for permission to increase air emissions, the public remains mostly unaware. The applying plant leaves a copy of its application at the local library, most of which is indiscernible to anyone without a degree in chemistry, and TCEQ holds a public comment session that has very little if any effect on the permit approval — which seems from the outset to be done deal.

Midlothian Breathe fundraise to buy air monitorsMidlothian Breathe members Allison Templeton, left, and Patricia Brown sell T-shirts to raise funds to buy air monitors in October last year. Photo by J.G. Domke.

Hunt wants to see the process become more transparent with local residents taking a stand for their air quality, and TCEQ and the applying plant having to defend any actions they take that result in more people having to breathe in what they dump into the air. She wants to embolden local citizens to confidently push their concerns through to policy makers and demand accountability. 

In the last several months, Midlothian Breathe has scaled up its efforts to gather air emissions information and bring its data up to standard. The group has now acquired engineering and air quality help in producing a grid-map for properly positioning sensors in Midlothian and will now raise funds to purchase the 20 total sensors the map calls for.

“As a first step, really we are just looking at it as a tool to promote more public awareness and public education about what's happening. It’s not just steam [coming out of the smokestacks],” she says, rebutting a typical dismissal that local plant representatives make when anyone becomes concerned about emissions.

“What I first see happening is just better awareness, increased public interest, more engagement between citizens, local government and the cement plants. As a starting point, I think we need to get to a place where it’s no longer acceptable for the cement plants to just basically do whatever they want.”

“What I first see happening is just better awareness, increased public interest, more engagement between citizens, local government and the cement plants. As a starting point, I think we need to get to a place where it’s no longer acceptable for the cement plants to just basically do whatever they want.”



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