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3 years later, Marshall Fire impacts still being learned

Rachel Sauer — Thu, 02 Jan 2025 21:23:38 +0000

3 years later, Marshall Fire impacts still being learned Rachel Sauer Thu, 01/02/2025 - 14:23

Colleen E. Reid

Wildfire smoke’s health risks can linger in homes that escape burning—as Colorado’s Marshall Fire survivors discovered

On Dec. 30, 2021, a wind-driven wildfire raced through two communities just outside ��«��Ƶ, Colorado. In the span of about eight hours, more than 1,000 homes and businesses burned.

The fire left entire blocks in ash, but among them, pockets of houses survived, seemingly untouched. The owners of these homes may have felt relief at first. But fire damage can be deceiving, as many soon discovered.

When wildfires like the Marshall Fire reach the wildland-urban interface, they are burning both vegetation and human-made materials. Vehicles and buildings burn, along with all of the things inside them—electronics, paint, plastics, furniture.

Colleen E. Reid, a CU ��«��Ƶ associate professor of geography, and her research colleagues created a checklist for people to use after urban wildfires in the future to help them protect their health and reduce their risks when they return to smoke-damaged homes.

Research shows that when human-made materials like these burn, the chemicals released are different from what is emitted when just vegetation burns. The smoke and ash can blow under doors and around windows in nearby homes, bringing in chemicals that stick to walls and other indoor surfaces and continue off-gassing for weeks to months, particularly in warmer temperatures.

In a new study released three years after the Marshall Fire, my colleagues and I looked at the health effects people experienced when they returned to still-standing homes. We also created a checklist for people to use after urban wildfires in the future to help them protect their health and reduce their risks when they return to smoke-damaged homes.

Tests in homes found elevated metals and VOCs

In the days after the Marshall Fire, residents quickly reached out to nearby scientists who study wildfire smoke and health risks at the ��«��Ƶ and area labs. People wanted to know what was in the ash and causing the lingering smells inside their homes.

In homes we were able to test, my colleagues found elevated levels of metals and PAHs – polycyclic aromatic hydrocarbons – in the ash. We also found elevated VOCs – volatile organic compounds – in airborne samples. Some VOCs, such as dioxins, benzene, formaldehyde and PAHs, can be toxic to humans. Benzene is a known carcinogen.

People wanted to know whether the chemicals that got into their homes that day could harm their health.

At the time, we could find no information about physical health implications for people who have returned to smoke-damaged homes after a wildfire. To look for patterns, we surveyed residents affected by the fire six months, one year and two years afterward.

Symptoms six months after the fire

Even six months after the fire, we found that many people were reporting symptoms that aligned with health risks related to smoke and ash from fires.

More than half (55%) of the people who responded to our survey reported that they were experiencing at least one symptom six months after the blaze that they attributed to the Marshall Fire. The most common symptoms reported were itchy or watery eyes (33%), headache (30%), dry cough (27%), sneezing (26%) and sore throat (23%).

All of these symptoms, as well as having a strange taste in one’s mouth, were associated with people reporting that their home smelled differently when they returned to it one week after the fire.

Many survey respondents said that the smells decreased over time. Most attributed the improvement in smell to the passage of time, cleaning surfaces and air ducts, replacing furnace filters, and removing carpet, textiles and furniture from the home. Despite this, many still had symptoms.

We found that living near a large number of burned structures was associated with these health symptoms. For every 10 additional destroyed buildings within 820 feet (250 meters) of a person’s home, there was a 21% increase in headaches and a 26% increase in having a strange taste in their mouth.

These symptoms align with what could be expected from exposure to the chemicals that we found in the ash and measured in the air inside the few smoke-damaged homes that we were able to study in depth.

The Marshall Fire swept through several neighborhoods in Louisville and Superior, Colorado. In the homes that were left standing, residents dealt with lingering smoke and ash in their homes. (Photo: Michael Ciaglo/Getty Images)

Lingering symptoms and questions

There are a still a lot of unanswered questions about the health risks from smoke- and ash-damaged homes.

For example, we don’t yet know what long-term health implications might look like for people living with lingering gases from wildfire smoke and ash in a home.

We found a significant decline in the number of people reporting symptoms one year after the fire. However, 33% percent of the people whose homes were affected still reported at least one symptom that they attributed to the fire. the same percentage also reported at least one symptom two years after the fire.

We also could not measure the level of VOCs or metals that each person was exposed to. But we do think that reports of a change in the smell of a person’s home one week after the fire demonstrates the likely presence of VOCs in the home. That has health implications for people whose homes are exposed to smoke or ash from a wildfire.

Tips to protect yourself after future wildfires

Wildfires are increasingly burning homes and other structures as more people move into the wildland-urban interface, temperatures rise and fire seasons lengthen.

It can be confusing to know what to do if your home is one that survives a wildfire nearby. To help, my colleagues and I put together a website of steps to take if your home is ever infiltrated by smoke or ash from a wildfire.

Here are a few of those steps:

When you’re ready to clean your home, start by protecting yourself. Wear at least an N95 (or KN95) mask and gloves, goggles and clothing that covers your skin.
Vacuum floors, drapes and furniture. But avoid harsh chemical cleaners because they can react with the chemicals in the ash.
Clean your HVAC filter and ducts to avoid spreading ash further. Portable air cleaners with carbon filters can help remove VOCs.

A recent scientific study documents how cleaning all surfaces within a home can reduce reservoirs of VOCs and lower indoor air concentrations of VOCs.

Given that we don’t know much yet about the health harms of smoke- and ash-damaged homes, it is important to take care in how you clean so you can do the most to protect your health.

Colleen E. Reid is an associate professor in the ��«��Ƶ Department of Geography.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Wildfire smoke’s health risks can linger in homes that escape burning—as Colorado’s Marshall Fire survivors discovered.

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Top image: Bmurphy380/Wikipedia Commons

Breaking bonds in 'forever chemicals'

Rachel Sauer — Fri, 20 Dec 2024 17:23:20 +0000

Breaking bonds in 'forever chemicals' Rachel Sauer Fri, 12/20/2024 - 10:23

Arindam Sau , Mihai Popescu and Xin Liu

We developed a way to use light to dismantle PFAS ‘forever chemicals’–long-lasting environmental pollutants

Perfluoroalkyl and polyfluoroalkyl substances, or PFAS, have earned the nickname of forever chemicals from their extraordinary ability to stick around in the environment long after they’ve been used.

These synthetic compounds, commonly used in consumer products and industrial applications for their water- and grease-resistant properties, are now found practically everywhere in the environment.

Arindam Sau, a Ph.D. candidate in the CU ��«��Ƶ Department of Chemistry, along with Colorado State University research colleagues Mihai Popescu and Xin Liu, developed a chemical system that uses light to break down bonds between carbon and fluorine atoms.

While many chemicals will degrade relatively quickly after they’re disposed of, PFAS can stick around for up to 1,000 years. This durability is great for their use in firefighting foams, nonstick cookware, waterproof clothing and even food packaging.

However, their resilience means that they persist in soil, water and even living organisms. They can accumulate over time and affect the health of both ecosystems and humans.

Some initial research has shown potential links between PFAS exposure and various health issues — including cancers, immune system suppression and hormone disruption. These concerns have led scientists to search for effective ways to break down these stubborn chemicals.

We’re a team of researchers who developed a chemical system that uses light to break down bonds between carbon and fluorine atoms. These strong chemical bonds help PFAS resist degradation. We published this work in Nature in November 2024, and we hope this technique could help address the widespread contamination these substances cause.

Why PFAS compounds are so hard to break down

PFAS compounds have carbon-fluorine bonds, one of the strongest in chemistry. These bonds make PFAS incredibly stable. They resist the degradation processes that usually break down industrial chemicals – including hydrolysis, oxidation and microbial breakdown.

Conventional water treatment methods can remove PFAS from water, but these processes merely concentrate the contaminants instead of destroying them. The resulting PFAS-laden materials are typically sent to landfills. Once disposed of, they can still leach back into the environment.

The current methods for breaking carbon-fluorine bonds depend on use of metals and very high temperatures. For example, platinum metal can be used for this purpose. This dependence makes these methods expensive, energy-intensive and challenging to use on a large scale.

How our new photocatalytic system works

The new method our team has developed uses a purely organic photocatalyst. A photocatalyst is a substance that speeds up a chemical reaction using light, without being consumed in the process. Our system harnesses energy from cheap blue LEDs to drive a set of chemical reactions.

After absorbing light, the photocatalyst transfers electrons to the molecules containing fluorine, which breaks down the sturdy carbon-fluorine bonds.

By directly targeting and dismantling the molecular structure of PFAS, photocatalytic systems like ours hold the potential for complete mineralization. Complete mineralization is a process that transforms these harmful chemicals into harmless end products, like hydrocarbons and fluoride ions, which degrade easily in the environment. The degraded products can then be safely reabsorbed by plants.

A wide variety of products can contain PFAS. (Graphic: City of Riverside, California)

Potential applications and benefits

One of the most promising aspects of this new photocatalytic system is its simplicity. The setup is essentially a small vial illuminated by two LEDs, with two small fans added to keep it cool during the process. It operates under mild conditions and does not use any metals, which are often hazardous to handle and can sometimes be explosive.

The system’s reliance on light – a readily available and renewable energy source – could make it economically viable and sustainable. As we refine it, we hope that it could one day operate with minimal energy input, outside of the energy powering the light.

This platform can also transform other organic molecules that contain carbon-fluorine bonds into valuable chemicals. For instance, thousands of fluoroarenes are commonly available as industrial chemicals and laboratory reagents. These can be transformed into building blocks for making a variety of other materials, including medicines and everyday products.

Challenges and future directions

While this new system shows potential, challenges remain. Currently, we can degrade PFAS only on a small scale. While our experimental setup is effective, it will require substantial scaling up to tackle the PFAS problem on a larger level. Additionally, large molecules with hundreds of carbon-fluorine bonds, like Teflon, do not dissolve into the solvent we use for these reactions, even at high temperatures.

As a result, the system currently can’t break down these materials, and we need to conduct more research.

We also want to improve the long-term stability of these catalysts. Right now, these organic photocatalysts degrade over time, especially when they’re under constant LED illumination. So, designing catalysts that retain their efficiency over the long term will be essential for practical, large-scale use. Developing methods to regenerate or recycle these catalysts without losing performance will also be key for scaling up this technology.

With our colleagues at the Center for Sustainable Photoredox Catalysis, we plan to keep working on light-driven catalysis, aiming to discover more light-driven reactions that solve practical problems. SuPRCat is a National Science Foundation-funded nonprofit Center for Chemical Innovation. The teams there are working to develop reactions for more sustainable chemical manufacturing.

The end goal is to create a system that can remove PFAS contaminants from drinking water at purification plants, but that’s still a long way off. We’d also like to one day use this technology to clean up PFAS-contaminated soils, making them safe for farming and restoring their role in the environment.

Arindam Sau is a Ph.D. candidate in the ��«��Ƶ Department of Chemistry; Mihai Popescu is a postdoctoral associate in chemistry at Colorado State University; Xin Liu is a postdoctoral scholar in chemistry at Colorado State University.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

We developed a way to use light to dismantle PFAS ‘forever chemicals’ – long-lasting environmental pollutants.

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Top image: PFAS foam washed up on beach (Photo: Michigan Department of Environment, Great Lakes and Energy)

Sand verbena uses grains of sand to deter herbivores

Rachel Sauer — Thu, 19 Dec 2024 19:41:09 +0000

Sand verbena uses grains of sand to deter herbivores Rachel Sauer Thu, 12/19/2024 - 12:41

Jeff Mitton

Apparently, herbivores are not fond of chewing sandpaper

Sand verbena, Abronia fragrans, has a moth pollination syndrome, or a suite of floral characters modified by natural selection driven by moth pollination. Its flowers are open all night but closed all day, and long corolla tubes prevent bees from taking nectar but are ideal for moths with long tongues.

Moths follow plumes of floral fragrance from sand verbena until they are within sight of the bright, conspicuous white globes of 25 to 80 flowers, where they sip a nectar reward.

Although sand verbena has a large geographic range, it is limited to sandy habitats in Texas, New Mexico, Arizona, Utah, Colorado, Oklahoma, Kansas, Wyoming, Montana, Nebraska, South Dakota and North Dakota. While sand verbena is described as having white flowers that open only at night, populations in northern Texas and southwestern Oklahoma have a range of flower colors from light pink through fuchsia, and they also differ from most populations in the times that flowers open and close.

The plants with pink or fuchsia flowers remain open until late morning, and they reopen in early evening, allowing considerable visitation by bees and butterflies. Measurements of pollination success in the pink and fuchsia populations showed that diurnal or daytime pollination contributed 18% of the pollination success, in contrast to nothing at all in the remainder of the geographic range of the species.

Dwarf lupine with patches and particles of sand on its flowers, leaves and stem. (Photo: Jeff Mitton)

These data are consistent with the hypothesis that diurnal pollinators were a selective force producing and maintaining novel flower color and diurnal presentation of open flowers in the mornings and late afternoons. The long corolla tubes frustrate bee efforts to collect pollen or nectar but hold nectar available to virtually all butterflies.

Butterflies are visiting diurnally—the most common among them is the skipper Lerodea eufala, the Eufala skipper. These data and other observations suggest the hypothesis that the Eufala skipper applied selective pressure to change flower color from white to pink or fuchsia and to modify the times that flowers open and close.

How could a butterfly apply selection pressure? This terminology unintentionally suggests that the butterflies had a plan and the organization to apply it. But that was not the case. If some flowers did not close exactly at sunrise and if a small butterfly pollinated them, enhancing their seed set, the genes that influenced tardy closing of flowers would become more common in the next generation.

The butterfly did nothing more than sip nectar from a large globe of flowers, nor did the sand verbena do anything to achieve an intended goal. The metric of natural selection is the relative number of offspring produced by competing genotypes of sand verbena. Genes that had been rare produce more seeds, making those genes more common.

Sand verbena is in the genus Abronia, which has about 20 species, all in North and Central America. All thrive in sandy environments, and it is known that 14 of the 20 species have psammophory, a defense to herbivory that is more commonly called sand armor. The armor is assembled when wind-blown sandy grit adheres to sticky exudates on stems and leaves.

I first encountered psammophory when photographing dwarf lupine in the Maze in Canyonlands National Park, and since then I thought it was a rare defense. But a scientific article whose title begins with "Chewing sandpaper" lists more than 200 psammophorous species in 88 genera in 34 families.

Sand armor is not a rare defense; it is geographically widespread and has evolved many times. Experimental studies show that sand armor reduces herbivory—remove it from stems and leaves, and the plant suffers more herbivory than when the armor was intact. Add more sand, and the plant suffers less herbivory.

While sand verbena has a large geographic range, some species of Abronia have tiny geographic distributions. One example is Yellowstone sand verbena, A. ammophila, which is adapted to and endemic (found nowhere else) to the lake shores in Yellowstone National Park.

An obligate relationship was found recently when a new species of moth, Copablepharon fuscum, was discovered in 1995 on the shores of the Salish Sea between Georgia Straight and Puget Sound. The sand-verbena moth was found on just a few beaches and spits on Vancouver Island and Whidbey Island, and it only occupies sites with windblown sand and large and dense populations of A. latifolia, yellow sand verbena, which is found along Pacific Shores from Baja to British Columbia.

The sand-verbena moth uses yellow sand verbena as its host plant, meaning that it is the site of oviposition and the sole food consumed by the caterpillars. The caterpillars have specialized mouth parts allowing them to manipulate around grains of sand.

I know I will never see a sand verbena nor a dwarf lupine without the phrase "chewing sandpaper" popping into my thoughts.

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Apparently, herbivores are not fond of chewing sandpaper.

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Top image: Sand verbena usually presents white blooms but response to a pollinator can turn a population pink or fuchsia. (Photo: Jeff Mitton)

Trailing fleabane looks delicate, but it flowered through a drought

Rachel Sauer — Tue, 26 Nov 2024 23:13:46 +0000

Trailing fleabane looks delicate, but it flowered through a drought Rachel Sauer Tue, 11/26/2024 - 16:13

Jeff Mitton

Flower was once thought to repel fleas, a belief long-since debunked

According to the U.S. Drought Monitor, ��«��Ƶ County was in severe drought in September and the beginning of October this year. On Oct. 14, I went up on Flagstaff Mountain to see what was blooming and to check the condition of some small cacti, Missouri foxtails.

The foxtails were shriveled and seemed to be shrinking into the earth, a common plight for cacti in drought conditions. But my attention quickly shifted to some delicate daisies—these were the only flowers blooming in the prolonged drought.

The flowering species was flowering was Erigeron flagellaris. The plants were about 8 inches tall and had the typical daisy bloom with numerous slender, white petals radiating from a central yellow disc. Erigeron is a large genus in the family Asteraceae, commonly called composites, because each of the blooms is a composite of yellow disc florets in the center and white ray florets radiating.

Each "petal" is a ray floret, a flower that is solely female and fertile. Each of the disc florets is bisexual and fertile. An E. flagellaris bloom has 40 to 125 ray florets and even more disc florets.

In addition to seeds produced by both ray and disc florets, E. flagellaris reproduces asexually by producing stolons, stems that grow horizontally, touching ground at each node.

Erigeron flagellaris, or trailing fleabane, flowers and their mature seeds (Photo: Jeff Mitton)

Contact with the ground stimulates a node to grow a new cluster of roots that support the growth of upright stems, leaves and more flowers. This asexual reproduction creates a spreading clone that, under the best of conditions, resembles a mat. The proliferation of stolons suggests its common names, trailing fleabane and whiplash fleabane. Strawberry plants also spread with stolons, but gardeners usually call them runners.

The genus Erigeron has about 200 species, many of them in North America and all with the common name fleabane. The name, originally from Old English and first used in 1548, comes from the belief that the plant's smell would repel fleas from a dwelling. Plants were either burned or hung in sachets. Both belief and practice were dispelled long ago—fleabanes do not banish fleas.

The Navajo were resourceful at finding preparations of plants that had practical uses for dyes and medicines, and they found a way to use the astringent properties released from crushed leaves of trailing fleabane. They would chew the leaves and then place the moist pulp directly on wounds to stop the bleeding.

Description of the scent of trailing fleabane is elusive. The website Southwest Colorado Wildflowers lists citations in which the scent has been described as spicy, camphor-like, ill-scented, mysterious and downright weird. Chemical studies of fleabanes shows that their fragrances come from essential oils, volatile liquids containing chemical compounds synthesized by the plant.

I was not able to find a study of the essential oil of trailing fleabane, but several other fleabanes have been studied, and all reveal a bewildering diversity of biologically active compounds. For example, a study of the essential oil in E. floribundus, which has the common names tall fleabane and asthma weed, has 85 biologically active compounds. Concentrations of the various compounds differ among fleabane species that have been studied, resulting in a diversity of fragrances.

The constituents in essential oils are undoubtedly expensive to synthesize, but many studies have shown that they contribute to the defense of the plant against herbivores, microbes and fungi. I see a parallel between the essential oils of fleabanes and the resins of pines, firs and spruces.

In fact, limonene is a component of both essential oils and resins. Laboratory studies have shown effective defensive activity of limonene in the oil of E. floribundus, and populations studies have shown that mountain pine beetles eschew ponderosa pines with high levels of limonene.

In summer months, as people camp, hike and generally play in the mountains, one often hears comments about the pleasant fragrance of stands of ponderosa pine, or a spruce and fir forest. But I have never noticed the smell of fleabanes. It is a certainty that herbivores such deer and rabbits note the smell and shun the plants; it is the primary defense of daisies.

The essential oils extracted from several fleabane species can be purchased on the web, but I am sure that sniffing a concentrated concoction of biologically active chemicals from a bottle and nasally inhaling in a field of fleabanes would be different experiences. Let's remember to go fleabane sniffing next summer.

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Flower was once thought to repel fleas, a belief long-since debunked.

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Trailing fleabane is small and appears delicate, but it is hardy and well defended. (Photo: Jeff Mitton)

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3 years later, Marshall Fire impacts still being learned

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