Understanding the risk profile for people who live or work near the Sterigenics Smyrna facility means looking at both distance (how far away someone is) and duration (how long or how often exposure has been happening).
According to Georgia Environmental Protection Division modeling, ambient air concentrations of ethylene oxide (EtO) around the plant exceed “Acceptable Ambient Concentrations” in many downwind areas under certain weather conditions.
The EPA’s National Air Toxics Assessment (NATA) and its technical reviews identified census tracts around Sterigenics Cobb County as having risks well above background for nearby communities.
Long-term exposure to even low levels of released ethylene oxide can lead to increased lifetime cancer risks, especially for those continuously breathing ambient air near the plant.
The risk is not uniform in all directions: prevailing winds, topography, and where emissions escape (chimneys, doors, aeration chambers) shape a plume that tends to carry contaminants farther downwind.
Scientific reviews (including the IRIS inhalation carcinogenicity assessment by EPA) show that EtO is a proved human carcinogen, especially for blood and breast cancers.
In addition to cancer, health agencies like ATSDR are evaluating non-cancer effects in Cobb County, using both air monitoring data and health consultation requests from residents.
Below are specific health risks and effects people living within different radiuses (1 mile, 2.5 miles, 5 miles) around the facility may face, and how these effects tend to develop over time:
- Increased cancer risk: Long-term exposure to EtO has been linked to elevated risks of breast cancer, leukemia (especially lymphocytic leukemia), non-Hodgkin lymphoma, and other lymphoid cancers. As exposure accumulates over years, the probability of mutation in cells increases.
- Respiratory effects: Coughing, throat irritation, shortness of breath; longer exposures can lead to more serious lung damage. Some studies suggest that in high-concentration events (or for those very near the facility), people may develop inflammation or reduced lung function.
- Higher risk for vulnerable populations: Children, the elderly, people with asthma or other baseline lung disease are more likely to suffer earlier or more severe effects. Continuous exposure (living/work/school) increases cumulative dose.
- Genotoxic effects / DNA damage: EtO is a mutagen; over time in both animals and humans, exposure has been shown to cause chromosomal aberrations and other changes that can precede cancer. IRIS and other EPA documents detail this mechanism.
- Non-cancer systemic effects and medical conditions: Potential for effects on reproductive health, neurological symptoms, immune system suppression—these manifest after prolonged exposure and often with a latency or lag (years after initial exposure).
People living closer (within ~1 mile) are generally going to have the highest average exposure; from 1 to 2.5 miles, risk decays but remains elevated depending on wind/terrain; by 5 miles, risks are lower but not negligible especially under downwind conditions, stable atmospheric layers, and if the facility has had poor emission controls.
Environmental Factors That Influence Ethylene Oxide Exposure Risks
People living in proximity to a sterilization plant like Sterigenics in Smyrna don’t face uniform risk.
Exposure to ethylene oxide (EtO) depends heavily on conditions in the air surrounding sterilization facilities and how the facility releases that gas.
Federal and state agencies, including the Georgia Environmental Protection Division (GA EPD) in coordination with the Environmental Protection Agency (EPA), have conducted detailed dispersion modeling for EtO from the Sterigenics facility.
That modeling showed that under current emission configurations (especially when fugitive emissions are vented to wall fans rather than roof stacks) ambient levels around residential areas exceed annual Acceptable Ambient Concentrations.
Meteorology plays a crucial role: prevailing wind direction, wind speed, temperature inversions, and atmospheric stability directly affect how far emitted EtO travels, how diluted it becomes, and which neighborhoods are downwind.
Local structures, nearby buildings and even terrain features cause downwash effects, which tend to pull plumes closer to the ground, increasing exposure for communities and workers exposed near those structures.
Stack height and release points matter too: whether EtO is released via roof stacks or lower wall vents changes effective stack height, which in turn changes ground-level concentrations.
The Sterigenics modeling memo compared the “current configuration” (with wall/fan vents) vs a “proposed configuration” where fugitive emissions are collected and released through higher roof stacks and found materially lower predicted exposures in residential areas with the proposed stack setup.
Regulatory design and engineering choices, like the use of scrubbers, back-vent monitoring, maintaining negative pressure in aeration rooms, and controlling leaks, are the other forms of risk mitigation; failure in any of those increases toxic exposure.
Communities and workers exposed under poorer control regimes will encounter higher effective doses.
Because EtO is a cancer-causing chemical with serious effects accumulating over time (often many years), even relatively modest exposures matter if they repeat over months and years, especially for people who are chronically exposed (via home/work/school near the facility).
