Is asphalt odor you smell toxic?


Central Asphalt produced over 14 million tons of aphalt on their facility throughout 40 years of operation.

When Anita Gross, a Mount Pleasant resident, got into the car to take her children to school, a pervasive heavy chemical odor had hit her nose. She had thought to herself, 'this is what something toxic smells like'. All Gross wanted to do at the time was close the doors and roll up the windows as quickly as possible. This happened 25 years ago.

Gross noticed the same smell this fall. 

What is it?

Chris Hare, a Michigan Department of Environment, Great Lakes and Energy (EGLE) district supervisor, confirmed the odor to be hot asphalt coming from Central Asphalt (CA), an asphalt paving company in Mount Pleasant. 

Hare said the smell is very odorous, but very low in toxicity. 

Since Sept. 22, EGLE received around a dozen complains from residents about the odor, Hare said. Complaints were documented in a survey on EGLE's website, which people can submit any time if they are concerned about the air quality in their location. 

Gross said the odor has always been around town, mostly noticeable on Flynn Lane, Pill Hill area, Tomah Drive and West High Street. Gross said she usually smells it early in the mornings. 

“I was very happy to move out of town to upland,” Gross said when referring to how the odor caused her discomfort.

Gross described the odor as “chemical” and “terrible” and the cause of the smell was a “mystery,” but she was worried if it was toxic.    

“I can understand why odors like that would be an annoyance to people who live close,” Lawrence Lemke said, a chair of the Department of Earth and Atmospheric Sciences. “My personal expectation is that it’s not really an emergency safety issue, but when you live next to a plant like that for 20, or 30, or 40 years maybe those things could be a long-term concern.” 

Are asphalt fumes toxic?

“I would say in general it’s not toxic,” Lemke said. “But is it possible (that) fresh installed asphalt could have emissions of gases? It’s not only possible, it’s probable.” 

Lemke said chemicals like Sulfur Dioxide and Polycyclic Aromatic Hydrocarbon are most likely to have odors that people could smell. Lemke said they could be considered potentially harmful at high concentrations. Lemke said everything, for example, even water, if used in a way that it is not supposed to, or in high concentrations, can harm the environment. What concentrations are allowed must be listed in a company's air quality permit.

The alternative to asphalt as a material is concrete. However, according to Lemke, when making fresh concrete, it would release carbon dioxide into atmosphere which also could be harmful.

“I would define anthropogenic air pollution as a presence of compounds or chemicals or even particular matter in the air that is generated by human activity,” Lemke said. “When we’re talking about pollution, we’re talking about something that’s not ordinarily there. And sometimes that can be harmful.” 

Rebecca Uzarski, an environmental health and safety program director at CMU, said Mount Pleasant's air quality is much higher and our area is much cleaner, than, for example, some areas of Detroit where there is a larger population and a lot of industries. 

“You have to remember that the pollution in the air is not just due to one industry,” Uzarski said. “There is farming in the area which could introduce pollution, there is automobile traffic that introduces pollution, other industries in the area are contributing.”

Lemke said pollution sources are divided into point sources and nonpoint ones. Farming area covered in pesticides and roads where oil from cars drop are considered nonpoint sources, whereas the smokestack from the asphalt plant would be considered a point one source.

“There’s always that possibility (of toxicity),” Lemke said. “But almost anything can be harmful if we experience it in excess. Even water can be harmful, right? If we swallow it or breathe it in a way that is not part of our regulated process.”

Uzarski said that toxicity of any asphalt odor depends on what kind of gases are emitted. She named common gases that are from burning fossil fuels. 

The Environmental Protection Agency (EPA) published a report where it determined what emissions there are in the hot mix asphalt.

“Hot mix asphalt is used primarily as paving material and consists of a mixture of aggregate and liquid asphalt cement, which are heated and mixed in measured quantities,” the report said. 

The gaseous emissions included sulfur dioxide (SO2), nitrogen oxides (NOx), carbon monoxide (CO), volatile organic compounds (VOC) and volatile HAP organic compounds.

On Dec. 16, 2014, EGLE issued an air quality permit to CA which showed that it was meeting all the air quality standards. The permit allowed installment of the listed in the permit emission units and attached their conditions.

The permit lists the emissions and its limits such as PM (particulate matter), Sulfur Dioxide (SO21 and SO22)  Nitrogen oxides (NOx) and Polycyclic Aromatic Hydrocarbon (PAH)3. 

How does the company address complaints?

Aaron White, a vice president of CA, said the operation of the CA is safe. He said the company follows its permit and state guidelines. 

“It is a very regulated system,” White said. 

For 40 years of the company’s operation, CA sometimes gets complaints about the odorous asphalt, White said. He said the latest one he could remember happened in 2009. 

“We certainly would ask anybody if they ever have any concerns, contact us directly, and we will be more than happy to offer them guidelines or information,” White said.  

Why do we smell asphalt?

White said he noticed the odor to be prevalent in cold weather. 

Uzarski said weather conditions can influence where chemicals from the asphalt plants go and how quickly they move. It is caused by wind direction, moisture in the air, temperature and stationary (if they are closer to the ground). She said it depends on the specific chemical involved. 

It happens because an aggregate that is mixed with an asphalt cement is heated at very high temperatures (350 degrees), which creates the steam. When that warmth meets the cold air, smell apprears, White said.

Lemke said asphalt is produced as a petroleum product, which means it contains aggregate (pieces of rocks), and is made by taking crude oil (petroleum), heating it up and letting it condense. At the top of crude oil product piramid, the end products such as jet fuel and gasoline are produced, at the bottom – we get asphalt. 

White shared an interesting fact that asphalt pavement is the number one most recycled product in the nation. He said when CA rips a road off, they bring asphalt back to the plant, crush it and reuse it again. 

How does the company deal with the odor?

White said CA has been trying to capture the smell. He said the company has filter bags and a bafhouse, which prevents particulates to be released to the air. They also have a loadout system which encloses around their trucks. 

Throughout the years CA has been improved White said. CA added silos for asphalt storage, loadout facilities and cold feed bins (used to measure aggregates). 

The company is still always looking for more technologies and equipment, White said. 

According to their permit, the required equipment is aggregate conveyors to transport materials, drum mixers to mix aggregates, fabric filter dust collector to collect dust and paving material product storage silo where hot mix asphalt is produced.

Who is in danger?

“The people who work with asphalt are the ones that are most at risk of exposure and health effects because they’re gonna be at contact with it every day,” Uzarski said. “And from a community standpoint when it’s introduced in the air, it’s going to be at a much lower level.”

White said CA’s employees are following safety measurements such as wearing safety glasses, hard hats and reflective yellow clothing. According to White, CA is operating under Occupational Safety and Health Administration (OSHA) which provides safety guidlines for workers in constructions, labs, hospitals etc.

“My employees are probably my most important asset as a company,” White said. “If we felt that we were doing something that was harming them, we wouldn’t be doing it.”

Uzarski said that some people might be more sensitive to airborne pollutants than others. She named those to be people with asthma, people who smoke, people who have chronic illness, children and elderly. 

Typically, people are exposed to pollutants by breathing. If they are sensitive, it could cause things like irritation, coughing, itchy eyes etc. 

Uzarski recommended if you know that you are sensitive, to be more aware of the air quality in the area.

EPA determines standards of air quality on its web-site.

What is going to happen next?

White said CA and EGLE have been working for already about a month checking the company’s operation. 

Hare said EGLE is investigating the toxicity in the odor coming from CA. Measurements for that are evaluation of emissions and data tests. 

“If we find that [the odor is toxic], we would send a letter to CA explaining the complaints,” Hare said. 

"Company (CA) is being very cooperative and they want to fix any issues they have,” Hare said. 

“We are members of this community,” White said. “We want to make sure that we address them (the complaints). Our goal is to operate invisible; you know, we want to be good stewards of the environment.”