Air pollution is a fundamental problem that affects the health and well-being of people all over the world. It is caused by a variety of sources, including industrial activities, transportation, and natural events like wildfires.
One of the most concerning aspects of air pollution is the phenomenon of re-entrainment, which occurs when polluted air is reintroduced into the atmosphere after it has been temporarily removed, in other words, moved from an indoor issue to the outside where it then comes back inside.
This article explores what re-entrainment is, why it poses a serious risk, and how it can be effectively prevented.
What is Re-entrainment?
Re-entrainment is a process in which pollutants (chemical or particulate matter) are reintroduced into ambient air after initially being removed. This typically occurs through environmental agitation, such as wind, traffic, or mechanical exhaust systems. Although the intent is to extract contaminated air from enclosed environments, improper exhaust strategies often lead to its return—sometimes directly into the same facility it originated from.
One of the most common culprits of presenting a re-entrainment issue is the use of a ducted fume hood, as polluted air is evacuated from a containment device and directed out of exhaust stacks. These exhaust stacks are positioned to reduce re-entrainment but may not be taking into consideration the developments of the surrounding area, HVAC intake locations, or prevailing wind patterns. As a result, expelled pollutants can re-enter occupied spaces—compromising air quality, staff safety, and building compliance.
Re-entrainment represents a hidden yet serious risk to indoor air quality and poses long-term health consequences for people working and living nearby.
What Can Be Done to Prevent Re-entrainment?
There are existing strategies that can be used to prevent re-entrainment of polluted air. One of the most effective is to use advanced filtration technologies that can remove, capture, and retain pollutants from the air at the source of pollution before they are released into the environment. These technologies can be used in a variety of settings, such as laboratories, industrial facilities, and transportation systems, to name a few, and can help to eliminate the amount of pollution that is reintroduced into the atmosphere.
Another strategy is to utilize windbreaks and other natural barriers to prevent polluted air from being carried by the wind to new locations. This can be particularly effective in areas where wind patterns are well understood and can help to protect nearby communities from the negative effects of air pollution. Though the variables and dynamics of mother nature may have other thoughts on this strategy. Even if wind breaks were effective for neighboring buildings, this has not addressed re-entrainment that can occur to the very same building which you are trying to protect. When at all possible, the best solution is to minimize what we through out into the atmosphere altogether and stop assuming that dilution is the solution to pollution.
Why Re-entrainment Is Never Acceptable in Any Situation
Re-entrainment is a serious matter that should not be overlooked as exposure to air pollution has been linked to a range of health problems, including respiratory illnesses, heart disease, and cancer. Expanding on these illnesses, some of the most common health effects associated with air pollution include:
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- Respiratory problems: Exposure to air pollution can cause a range of respiratory problems, including coughing, wheezing, and shortness of breath. Long-term exposure to air pollution can also lead to chronic respiratory conditions, such as asthma and chronic obstructive pulmonary disease (COPD).
- Cardiovascular disease: Air pollution has been linked to an increased risk of cardiovascular disease, including heart attacks and strokes. Exposure to air pollution can lead to inflammation in the body, which can contribute to the development of cardiovascular disease.
- Cancer: Some types of air pollutants, such as benzene and formaldehyde, have been linked to an increased risk of cancer. Exposure to these pollutants can increase the risk of developing lung cancer, as well as other types of cancer.
- Neurological problems: Exposure to air pollution has been linked to an increased risk of neurological problems, including cognitive decline and dementia. Air pollution can also contribute to headaches, dizziness, and other neurological symptoms.
- Reproductive problems: Exposure to air pollution can contribute to reproductive problems, including infertility and low birth weight. Air pollution can also increase the risk of premature birth and other complications during pregnancy.
- In addition, air pollution can have negative effects on the environment, including damage to crops, forests, and other natural resources.
In addition to health and environmental impacts, the economic consequences of re-entrainment are significant, placing financial burdens on individuals, businesses, and governments alike.
The Economic Costs of Re-entrainment
The cleanup and long-term management of polluted air carry serious financial consequences. Costs include:
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- Health care costs: Exposure to polluted air can lead to a range of health problems, including respiratory illnesses, heart disease, and cancer. The costs associated with treating these illnesses can be significant, and can place a burden on individuals, health care providers, and governments.
- Lost productivity: People who are exposed to polluted air may experience a range of symptoms, including headaches, fatigue, and difficulty breathing. These symptoms can make it difficult for people to work and can lead to lost productivity and economic activity.
- Property damage: Air pollution can cause damage to buildings, crops, and other property. This can result in costs for repairs and replacements, as well as lost income for businesses that rely on these resources.
- Environmental remediation: In some cases, it may be necessary to clean up polluted air to protect the environment. This can involve costly remediation efforts, such as soil and water cleanup, which can have significant economic impacts.
- Regulatory compliance: Governments may impose regulations on businesses and industries to reduce air pollution. Compliance with these regulations can be costly, as businesses may need to invest in innovative technologies or processes to meet the requirements.
While federal data highlights a 73% reduction in six key pollutants since 1970, new threats continue to emerge. As of 2023, more than 200 toxic air contaminants are monitored, with an estimated cancer risk of 730 per million from total air toxics—520 of which are attributed to diesel particulate matter alone.
According to EPA projections, reducing PM2.5 to background levels could prevent annually:
- 7,200 premature deaths
- 1,900 hospitalizations
- 5,200 emergency room visits
When you add climate-related air instability, including rising temperatures and wildfire smoke, we face a worsening scenario of chronic exposure and environmental stress.
Addressing the Problem With Proven Solutions
There are many positive steps that companies can take to halt the spread of current emissions tied to re-entrainment that will improve workers’ health and the number of premature deaths from air pollution.
One of the easiest solutions to implement is adding mechanical and effective air filtration within the occupied spaces. Proper filtration will reduce particles, chemicals, and infectious aerosolized droplets. Implementing such systems can create an environment that maintains a superior level of cleanliness.
As with any engineered control system, a site-specific assessment should be conducted by a qualified professional to account for airflow, room usage, and pollutant sources. This ensures the system is tailored to real facility conditions—not generalized standards.
Conclusion
Re-entrainment of polluted air presents clear and measurable harm—to health, environmental quality, regulatory standing, and business productivity. When organizations ignore this risk, the consequences can include increased illness, reduced workforce performance, and escalating remediation costs.
The solution is clear: adopt advanced filtration technologies that contain and neutralize pollutants at the source. Doing so protects not just employees, but also neighboring communities and the environment.
Clean air is a non-negotiable foundation for safety, sustainability, and responsible business operations.
If You’re Concerned About the Quality of the Air you Breathe, We’re Here to Help
Contact Erlab to learn how advanced containment and filtration solutions can help reduce re-entrainment and improve the air quality in your facility.