Sometimes science becomes too hot to handle. That’s what researchers at the University of Arizona found recently when they tried to test a new air pollution monitoring system around Tucson.
The scientists set out to install new equipment and implement a standardized protocol for monitoring levels of NO2, NOx, PM-2.5 and PM-10, four common air pollutants, that is already being used in 16 European countries. By adopting the same method of air quality evaluation used in ongoing studies elsewhere, they hoped to be able to improve comparisons of Tucson’s air pollution with levels in other environments and to test the accuracy of data from existing instruments around Tucson that are operated by the U.S. Environmental Protection Agency.
The idea was that, with more data that is more comparable to other global monitoring systems, they could better track changes in air pollution at neighborhood-level scales and address their impacts on human health.
But then their instruments failed.
“We had bought these pumps because (the manufacturer) had said that they had been field tested by the military in Iraq,” said Paloma Beamer, one of the authors of the recent study, which was published in the scientific journal Environmental Research and Public Health earlier this month. “But then (they said), ‘no, they can’t operate at this temperature.'”
When, in the middle of their year of data collection, summer temps spiked in Tucson, some of the motors on the monitoring equipment pulling in air to sample levels of particulates “blew their gaskets,” Beamer said. They had to improvise.
Fortunately, before becoming a professor of environmental health sciences in the Mel and Enid Zuckerman School of Public Health at UA, Beamer was trained as an engineer. She figured out how to modify the monitoring equipment, “MacGyvering” boxes with insulation and fans around the motors to cool them so the research could resume. And she was, admittedly, excited about her technical skills being called into action.
But she worries about what this situation might foreshadow in terms of the future of air quality studies in Tucson and other environments that are becoming hotter, drier, dustier and more extreme as a result of climate change.
“We are in this environment that is what more of the world is going to resemble in 10 to 20 years,” Beamer said. “And if we don’t focus on some of these extreme conditions, we’re not going to know how to prepare ourselves. It’s kind of a forewarning of what may happen.”
It’s another way climate change threatens health
The four air pollutants these UA scientists measured are not the only ones with human health impacts. Ground-level ozone, carbon monoxide, lead and sulfur dioxide are also considered “criteria air pollutants” by the EPA and regulated based on standards set by the Clean Air Act of 1970. The agency also keeps a list of 187 other hazardous air pollutants (HAPs) identified by the Clean Air Act that it (theoretically) regulates in the name of safeguarding human health.
The researchers in this study chose to focus on ambient nitrogen dioxide (NO2), oxides of nitrogen (NOx), and two sizes of particulate matter (PM-2.5 and PM-10) because the first three are byproducts of combustion from industry and vehicle emissions, while the last typically results from the type of dust storms, or “haboobs,” common throughout Arizona during the summer monsoon.
According to the Arizona Department of Environmental Quality (ADEQ), nitrogen oxides (including NOx and NO2) are highly reactive gases that result mostly from fuel combustion by vehicles and can combine with other compounds in the air to form additional hazardous types of air pollution, including ground-level ozone and small particulate matter.
Particulate matter, or particle pollution, is a mixture of particles, such as dust, with water vapor and gases that is commonly measured in two size categories, PM-2.5, or “fine particles” and PM-10, or “inhalable coarse particles.” These air pollutants can originate from a variety of sources, but are also the result of vehicle emissions.
All four air pollutants measured by the new monitoring equipment in Tucson have been shown to cause respiratory problems, including airway inflammation and asthma, as well as respiratory disease like emphysema and bronchitis. Their inhalation can also exacerbate pre-existing lung and heart conditions and has been linked to premature death in vulnerable people who already struggle with respiratory issues.
Matthew Pace, an air quality meteorologist with ADEQ, says that, despite population growth and increasing urbanization, Arizona’s air quality has actually improved in recent decades. But there’s still work to be done.
“The Clean Air Act really did a super good job of putting a lot of regulations on cars and making them more efficient,” Pace said. “Around 64 to 82% less emissions come out of newer cars versus older cars. Industry has also gotten better. But now it is time that we do start to call on the public to make those smaller reductions, because you might not think it’s much but if everyone does their part, it becomes a big reduction in the end.”
Pace recommends that Arizonans pay attention to air quality levels reported by the ADEQ to be mindful of their exposure at different times of the day. One way to do this is by downloading the ADEQ’s free air quality app, the ‘Air Arizona Mobile App.’
The data necessary to report air pollution levels in an app or to study their influences on human health, though, relies on functioning monitoring equipment, of course. And climate change, in addition to being a result of polluting emissions and interacting with air pollutants in other ways, seems to be throwing a wrench in that part of our functioning society, by causing average temperatures to exceed the thresholds at which these sensitive instruments were designed to operate.
The costs of having to “MacGyver” science
Nathan Lothrop was a postdoctoral research associate at the Asthma and Airway Disease Research Center at the UA when he started work on the recently-published study testing a new air pollution monitoring system in Tucson. He set up monitoring equipment at 40 different sites in settings that ranged from more regional to more urban and street-level locations.
They started the planned year of sampling in September and, at first, it went well. But then May rolled around and the pump motors started to fail in the summer heat and sun.
“There’s this picture of this funny looking stuff in the paper that shows this reflective Mylar material you would use in your car to reflect the sunlight and keep your car cool,” Lothrop said. “We were probably just pushing these pumps to their limits, even though I think they should have been OK.”
Lothrop says that this unexpected problem with equipment designed to function in hot environments raises concerns about the costs of basic air pollution monitoring in the future.
“This equipment costs money to run, it costs money to buy. As weather patterns get more extreme, it will probably be likely that these monitors are less and less representative of a whole city’s exposure to an air pollutant,” Lothrop explained. “And the reason we care about that is that we know different people around town have different levels of exposure to air pollutants around their house, and these monitoring systems may not do as great of a job in the future of capturing that.”
One of the consequences of globally increasing average temperatures that was detailed by scientists in the most recent report from the Intergovernmental Panel on Climate Change is that weather is expected to get “weirder,” with storms and conditions having stronger and more localized impacts. A heavy rain might fall on one neighborhood while the next one over stays bone dry, for example. This would create pockets of higher air pollution relative to a city’s average and necessitate more, and more accurate, monitoring equipment to correlate specific pollutants with health outcomes.
This can quickly become an environmental justice issue. Investigations have shown that minority and lower-income communities are often exposed to much higher levels of hazardous air pollution. Although Tucson, overall, actually has pretty low levels of air pollutants, it’s still important to collect data on how that relates to health over time, and to do it at a neighborhood-level scale, Beamer said.
“Even at the lower levels that we were looking at (in a different study), we did see associations with health outcomes,” Beamer said. “We saw stronger effects among children who had at least one black parent. That could be for a lot of reasons, (including) systemic racism and higher exposure.”
In a final twist, Lothrop, Beamer and colleagues also found that their monitoring equipment did not record the same levels of PM-2.5 as the EPA devices they were placed next to. In some cases, their equipment measured this small particulate pollutant at nearly twice the levels picked up by the corresponding EPA system. Other times, their readings were lower.
This raises questions about how increasing temperatures and changes in air-mixing patterns associated with climate change may complicate future data collection, and increase the cost, often to taxpayers, of doing science.
“These are things that we now need to think about for the future that we didn’t need to think about before,” Lothrop said.
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