What Is the AQI Scale, and What Is Considered Healthy Indoor Air Quality?
What Is AQI?
The Air Quality Index (AQI) was developed by the U.S. Environmental Protection Agency (EPA) to provide a simple way to communicate outdoor air quality and the potential health effects associated with common air pollutants.
The AQI considers several pollutants, including:
- Ground-level ozone
- Sulfur dioxide (SO₂)
- Nitrogen dioxide (NO₂)
- Carbon monoxide (CO)
- Fine particulate matter (PM₂.₅)
- Coarse particulate matter (PM₁₀)
Although AQI was developed for outdoor air quality, many facilities also use particulate monitors indoors to track airborne particulate levels and evaluate the effectiveness of their air filtration systems.
Understanding PM2.5 and PM10
Particulate matter is commonly grouped into two categories:
- PM₂.₅ – Particles that are 2.5 microns and smaller
- PM₁₀ – Particles between 2.5 and 10 microns
These particles are small enough to remain suspended in the air for extended periods. Many industrial processes—including CNC machining, cold forming, grinding, welding, and heat treating—produce large amounts of fine particulate that can significantly affect indoor air quality.
Oil smoke generated during machining is often between 0.1 and 1 micron, making it especially difficult to capture without properly designed air filtration equipment.
What Is a Good AQI?
The EPA classifies outdoor air quality using the following AQI ranges:
| AQI | Air Quality |
|---|---|
| 0–50 | Good |
| 51–100 | Moderate |
| 101–150 | Unhealthy for Sensitive Groups |
| 151–200 (Kn95 Masks Suggested) | Unhealthy (Kn95 Masks Suggested) |
| 201–300 | Very Unhealthy |
| 301–500(Kn95 Masks or better required) | Hazardous (Kn95 Masks of better required) |
While these categories were created for outdoor air, they provide a useful reference point when monitoring particulate levels inside manufacturing facilities.
For most industrial environments, maintaining particulate levels that consistently correspond to an AQI below 100 is a reasonable goal, although specific OSHA exposure limits and process requirements should also be considered.
How Can You Measure Indoor Air Quality?
Many companies offer professional indoor air quality testing, including Bee Clean Specialties.
Portable air quality monitors are also widely available and allow facilities to continuously monitor airborne particulate levels. Because many of the particles produced during manufacturing are invisible to the naked eye, poor air quality is often impossible to detect without proper instrumentation.
Monitoring air quality over time can also help identify:
- Plugged filters
- Poor source capture
- Inadequate airflow
- Changes in manufacturing processes
- Air filtration systems requiring maintenance
Is an AQI Below 100 Achievable in Manufacturing?
Many manufacturers assume that clean indoor air is impossible because their processes generate large amounts of smoke or mist.
In reality, facilities performing operations such as:
- Cold heading
- Precision CNC machining
- Grinding
- Heat treating
- Metal forming
Have successfully achieved below AQI 100 indoor air quality through proper air filtration system design and maintenance.
Depending on your facility, improvements may include:
- Preventative maintenance
- Cleaning electrostatic collection cells
- Replacing filters
- Improving source capture
- Redesigning ductwork
- Increasing airflow
- Installing additional air filtration equipment
- Ventilation
With the proper system design, many facilities can significantly reduce airborne particulate while improving employee comfort and visibility.
Bee Clean Specialties Can Help
Bee Clean Specialties has helped manufacturers improve indoor air quality throughout the Midwest by servicing and maintaining SmogHog®, MistBuster®, Tri-Mist®, Trion®, Aerocology®, Absolent®, and many other industrial air filtration systems.
Filtration Systems of Troy, Michigan and Bee Clean Specialties have both serviced industrial air filtration systems throughout Michigan for many years. Today, Bee Clean Specialties continues helping manufacturers improve indoor air quality through preventative maintenance, filter exchange programs, system upgrades, and new air filtration system installations.
If you would like to evaluate your facility’s indoor air quality or discuss ways to improve your air filtration system, contact Bee Clean Specialties at 847-451-0844.