Translating the EPA reports on the Chemtool Fire

A plume of black and grey smoke rises from the Chemtool plant in Rockton, IL on Monday, June 14th. Photo by Asia Michaela.

A plume of black and grey smoke rises from the Chemtool plant in Rockton, IL on Monday, June 14th. Photo by Asia Michaela.

By now I’m certain we have all heard about the fire and explosion at the Chemtool plant in Rockton. Whether you or a loved one responded to the fire, had to evacuate, saw or smelled the smoke plume, or even just read other people’s accounts of what happened, this fire brought up a lot of emotions in our community. 

As a Nature Center, we have three main goals: preserving nature, engaging in scientifically sound research, and educating the public. So when an event such as this fire occurs that has the potential to dramatically affect our environment and everything and everyone that lives in it, it is our turn to step in and do what we do best— help people understand what is occurring in our natural world. 

With so much information flying around the news and social media, I wanted to take some time to dissect the EPA reports that have been released so far. I know scientific reports like these are inaccessible and overwhelming to many, if not most people, so I want to use my training as a biologist to help translate the tables, numbers, and maps into language that we can all digest. So make yourself comfy, grab your favorite beverage, and get ready. This is going to be a long one.

Black smoke behind a nest of Bald Eagles at Nature at the Confluence in South Beloit, IL on the day of the explosion. Photo by Therese Oldenburg.

Black smoke behind a nest of Bald Eagles at Nature at the Confluence in South Beloit, IL on the day of the explosion. Photo by Therese Oldenburg.

What Happened?

In the early morning of Monday June 14th, a fire broke out at the Chemtool Production Center in Rockton. This facility manufactured products like greases, lubricants, metalworking fluids, cleaners, and corrosion inhibitors. In other words, lots of chemicals. The burning of all of these chemicals and the resulting explosion produced the black plume of smoke and debris that so many of us witnessed. 

In a normal fire, fire fighters will spray water onto the flames to cut off the oxygen it needs for fuel and to decrease the temperature. And for the first few hours, this is what first responders did. However, since the Chemtool plant was located directly next to the Rock River, the Rockton Fire Department (RFD) decided to stop using water to extinguish the fire due to fears of contaminated water running off into the river. So, in collaboration with the Illinois and Federal Environmental Protection Agencies (EPA), they decided to explore other options. 

Spraying foam is often used to extinguish fires involving flammable liquids, and with so many flammable liquids on site, the RFD and EPA considered this option. Before making the decision to apply foam, they wanted to consider the environmental impacts this would have. Unfortunately, before they were able to discuss their options, they were alerted that U.S. Fire Pump, a firefighting company hired by Chemtool, had already been applying PFAS foam (more info on this later) for about three hours, without consulting the Rockton Fire Chief. 

The Rockton Fire Department and EPA immediately halted the application of PFAS foam, and later began applying the environmentally safer non-PFAS foam.

A map from the U.S. EPA of some of the air quality monitoring sites.

A map from the U.S. EPA of some of the air quality monitoring sites.

What are they measuring?

Now that we have some background, let’s dive into some of the data that the Environmental Protection Agency has been collecting. They have been collecting air, water, and soil samples since the fire broke out, and so far their reports have contained a lot of information about air quality.

First of all, it is important to know what the EPA has been looking for in all these air samples they have been collecting. Here is the run-down of what they are monitoring for: 

  • Volatile organic compounds (VOCs): These are a group of chemicals that can vaporize (turn into a gas) in the atmosphere. Volatile means easily changed, and organic means the chemical contains carbon, so these are chemicals that contain carbon and can be easily changed into a gas. As outdoor air pollutants, the main concern is the potential for VOCs to react with sunlight to form smog. Smog decreases visibility, can irritate your eyes, nose and throat, and may worsen heart or breathing problems. Any more than 1 part VOC per million air particles (ppm) is over the health screening level.

  • Oxygen: Just the classic stuff that we need in order to breathe. The EPA wants to make sure that the oxygen levels in the area are where we want them to be.

  • Hydrogen sulfide: This is the stuff that smells like rotten eggs. It is naturally produced by things like volcanos and hot springs, but can also be created from industrial sources. Low levels of exposure to hydrogen sulfide can lead to respiratory problems, eye, nose, and throat irritation and worsening asthma. Additionally, exposure to low hydrogen sulfide levels can cause problems with the nervous system, which can lead to tiredness, balance issues, headaches, and memory problems. Anything over 0.1 ppm is considered above the health screening level. 

  • Carbon monoxide: This is a gas released whenever something is burned. Fossil fuel powered vehicles and machinery are common sources of carbon monoxide pollution. Elevated carbon monoxide in the air can lead to issues for people with heart disease such as reducing the amount of oxygen going to the heart and chest pains. Anything over 50 ppm exceeds health screening levels. 

  • Lower explosive limit (LEL): This the the smallest amount of flammable gas in the atmosphere that it takes to create an explosion. If the air contains only a tiny percentage of gas, it will not have the fuel needed to create an explosion. The EPA is making sure that any flammable gas that might have been given off during the fire is not present in large enough quantities to start another explosion. The specific value of the lower explosive limit depends on which gases are present, so it differs with each situation. 

  • Particulate matter (PM): This is the combination of solid particles and liquid droplets in the air. The EPA is measuring two different types of particulate matter, PM2.5 and PM10. The only difference between these two is the size of particulates that they measure. PM10 measures particulate matter that is 10 micrometers and smaller, and PM2.5 measures particles and droplets that are 2.5 micrometers or smaller. For scale, there are 1000 micrometers in a single centimeter, which is about the width of a fingernail. Both types can cause significant health and environmental problems, including heart and lung issues, making the air hazy, and forming acid rain. Anything higher than 0.025 mg of PM2.5  per cubic meter of air exceeds the health screening levels, and any PM10 above 0.05 mg per cubic meter exceeds these levels. 

  • Hydrogen cyanide (HCN): This is produced when man-made materials like plastics are burned. It can be very dangerous if ingested, and was even used as a chemical weapon during World War I. Hydrogen cyanide has the potential to contaminate air, water, soil, and foods, but is generally not a major problem outdoors because it can disperse quickly. Exposure to small amounts can lead to dizziness, headaches, nausea, breathing problems, restlessness, and general weakness. When present at 1 ppm or less, it has not been shown to produce health problems. 

  • Methylene diphenyl diisocyanate (MDI): This is a chemical with lots of commercial uses. MDI can cause skin and respiratory problems like contact dermatitis and asthma. Anything that exceeds 5 MDI parts per billion parts air exceeds health screening levels. 

I know this is a lot of abbreviations, long names, and scary facts, but if we want to understand the reports, this is information that we’ll need to know. Feel free to refer back to this section while reading through the rest of this post!

What do we know?

Now that we know what all the abbreviations stand for, as well as some background on what each of these terms mean, we can dive into the reports themselves. The U.S. EPA has been releasing summary tables of the data they collect each day, so let’s take the air quality data day-by-day.

Copy of Air Quality (1).png
  • June 14: EPA begins monitoring air quality at 1:10pm, about 6 hours after the fire begins. Elevated particulate matter is recorded at the plant. 

  • June 15: Elevated hydrogen cyanide levels are recorded near the plant. High particulate matter is recorded at 4 of 8 tested offsite locations. 

  • June 16: High particulate matter levels are recorded at 2 of 8 tested locations.

  • June 17: High particulate matter is observed at 2 of 6 tested sites within the evacuation zone. Three monitoring stations are added to the grounds of the Old Settlers Day (OSD) festival, which do not show any levels above safety standards.

  • June 18: High particulate matter levels are recorded at all 6 tested sites within the evacuation zone. High VOCs are seen at 1 of the 6 sites. All testing sites on OSD grounds show levels within safety levels

  • June 19: High particulate matter is observed at 2 of 3 sites on Old Settlers Day festival grounds in the evening. High particulate matter at 7 of 7 sites tested in the evacuation zone in the evening. 

  • June 20: During the day, high particulate matter is recorded at all 3 OSD sites and 7 of 13 other tested sites. That evening, particulate matter was elevated at all 3 OSD sites as well as 8 of 13 other sites. High VOCs were recorded on OSD grounds. Elevated levels of MDI occurred at 3 of 7 sites within the evacuation zone, and high hydrogen sulfide was seen at 2 of the 7 sites

  • June 21: Elevated hydrogen sulfide levels were recorded at 2 of 10 sites. High MDI was seen at 1 of 10, and high hydrogen cyanide levels occurred at 2 of 10 sites tested

  • June 22: Elevated levels of particulate matter were recorded at 2 of 11 sites tested during the day. Only 1 site showed elevated particulate matter that evening. 

  • June 23: Elevated levels of particulate matter were seen at 3 of 11 testing sites.

These graphs show the highest value of particulate matter recorded for each monitoring period. PM values from the EPA reports are given in a range, and this graph shows the high end of that range. The red dashed lines signify the Public Health Screening Level. The different colored dots correspond to distance from the Chemtool plant, with orange being directly on the site, green dots being within the 1 mile evacuation zone, and blue representing locations beyond 1 mile from the plant.

Phew! That much data and information can really feel overwhelming! Feel free to take a break, read back through anything that is still confusing, check out the graphical depictions of the data, and know that it takes scientists a long time to learn how to intellectually and emotionally process this much data. You are doing a great job by making it this far! 

What don’t we know?

If you are ready for more, we can talk about the things we are still waiting to learn about. Many tests take time, so although it can be frustrating, it is not surprising that we don't have information about many of these things. 

The Illinois EPA has been conducting tests on soil and water quality. Many water quality tests can take up to 6 weeks before results are available. So in the meantime, we can at least learn about which tests they are running and what they’re looking for. Here’s the list of tests that they will be conducting on water samples taken from the Rock River and local groundwater sources. 

  • Biochemical Oxygen Demand (BOD5): Directly, this test measures how much oxygen is needed for microbes in the water to break down material. Like you and me, many microbes need oxygen in order to survive. And just like how we breathe harder when we exercise, microbes need to use more oxygen when they work harder. Since these microbes live in the water, the only oxygen they have access to is dissolved in the water itself! By testing how much oxygen the microbes are using in a water sample, we can tell how hard they are working to decompose things like chemicals, plant debris, and animal waste. This can give us a good idea how much yucky stuff is in the water. Thanks microbes! 

  • Total Suspended Solids (TSS): Think of this as the equivalent of Particulate Matter, but in a water sample. This test looks at how much stuff over 2 micrometers in length is floating around in the water. They could be bits of soil, small pieces of plant material, or debris from human activities. 

  • Nutrients: This will be a test of what is in the water samples. Some nutrients like phosphorus and nitrogen can lead to algal blooms which can be harmful to the environment, so we would like to know which nutrients the water samples contain. 

  • Metals: I’m sure this is no surprise to any of you, but heavy metals can be very harmful to both people and the environment when they enter our waters. The IL EPA will be doing testing to make sure that the Chemtool explosion didn’t lead to any metal pollution entering the river or groundwater. 

  • Volatile (VOC) and semi-volatile organic compounds (SVOCs): Just like the VOCs we mentioned in the air quality section, these chemicals can also dissolve in water. Semi-volatile organic compounds are chemicals that can dissolve in water or vaporise in air, but not as easily as other VOCs. These SVOCs need to be exposed to higher temperatures in order to dissolve in water or vaporise into the air. 

  • Per- and Polyfluoroalkyl Substances (PFAS): This is a group of man-made chemicals that are used because they are oil and water-resistant. This makes them very helpful for putting out fires, especially those that can’t be extinguished using water alone. But there’s a drawback: these chemicals do not break down under natural conditions. This means once they are created, they will be around in the atmosphere forever, which has led to their nickname, “forever chemicals.” These properties also cause them to bioaccumulate. This means they continue to build up in your body if you are exposed to them and can take years to leave. This also means that PFAS can be passed from a pregnant or nursing person into their child. Scientists are still learning about the human health effects of PFAS, but according to the Illinois EPA, there is already evidence that have linked PFAS exposure to “increased cholesterol levels, increased risk for thyroid disease, low infant birth weights, reduced response to vaccines, liver and kidney toxicity, and pregnancy-induced hypertension”. Exposure levels tend to be higher in children and pets since they drink more water relative to their body size than adults do. 

Please join me in taking a deep breath after reading through all of that technical information. *Inhale… exhale* If you’ve gotten this far, you are truly doing a tremendous job, and it is totally normal for your brain to hurt after all of that (I know mine does!). 

Just remember that all of these water quality tests are still being run, so we don’t have information about what the river or groundwater contain just yet. I also haven’t been able to find any information about which tests are being run on the soil samples that have been collected by IL EPA, but once they release that data, you can bet that I will be back with another (hopefully shorter) post about the results of those tests! 

To keep an eye out for the data being released, you can check out these websites: 

Illinois EPA

Federal EPA

Winnebago County Public Health

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