Submicronix — Precision Air Quality.

White Papers

The science behind the invisible environment.

Explore the research informing our approach to aerosol science, particulate exposure, contamination control, filtration, and indoor environmental quality.
Beyond HEPA: Why Agglomeration + ULPA Vacuuming More Effectively Reduces Mold-Related Health Risk
No. 01
Filtration

Beyond HEPA: Why Agglomeration + ULPA Vacuuming More Effectively Reduces Mold-Related Health Risk

A White Paper on Mold Fragments, Mycotoxin-Associated Dust, and Submicron Particulate Control in Post-Remediation Environments

Most mold remediation efforts rely on HEPA filtration to capture spores — but homes pass inspection while occupants don't recover. This paper examines why submicron mold fragments and mycotoxin-associated dust persist after standard remediation, and how propylene glycol agglomeration combined with ULPA vacuuming addresses the particle fraction that HEPA alone misses.

By Cesar Collado
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Beyond HEPA: Part II — The 0.12–0.3 Micron Gap
No. 02
Health

Beyond HEPA: Part II — The 0.12–0.3 Micron Gap

Ultrafine Mold Fragments, Blood–Brain Barrier Dynamics, and Post-Remediation Neuroinflammatory Risk

Post-remediation environments frequently meet conventional clearance standards, yet a subset of occupants continue to experience persistent neurological, inflammatory, and endocrine symptoms. This paper examines the 0.12–0.3 micron particulate fraction — exponentially more numerous than spores — and the biologically plausible pathways by which ultrafine mold fragments may access central nervous system structures.

By Cesar Collado
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Beyond HEPA: Part III — Clinical Evidence of Harm from Submicron Particulates (<0.3 µm)
No. 03
Mold & Fungal Fragments

Beyond HEPA: Part III — Clinical Evidence of Harm from Submicron Particulates (<0.3 µm)

Implications for Post-Remediation Health — Clinical and Translational Observations

Despite meeting visual, moisture, and spore-based clearance criteria, a persistent subset of occupants experience ongoing respiratory, neurological, and systemic symptoms. This paper synthesizes evidence from aerosol science, environmental microbiology, and clinical research to demonstrate that residual submicron fungal fragments and dust-bound mycotoxins represent a biologically significant exposure fraction overlooked by conventional remediation endpoints.

By Cesar Collado
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Propylene Glycol Fog in Industrial Applications
No. 04
Particle Science

Propylene Glycol Fog in Industrial Applications

Aerosol Physics, Established Uses, and Implications for Submicron Particulate Management

Propylene glycol fog has been widely used across industrial environments for disinfection, dust suppression, and airflow visualization — yet the underlying aerosol physics governing its interaction with ultrafine particulate matter remain under-integrated across disciplines. This paper reviews PG aerosol properties, established industrial applications, and how Brownian motion, particle agglomeration, and size-dependent settling dynamics make PG fogging a meaningful intervention for submicron contamination control.

By Cesar Collado
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Submicronix white papers represent original research and applied observations by our team. Content is for informational purposes only and does not constitute medical or clinical advice.

References

Sources cited across the series.

A consolidated bibliography of the standards, peer-reviewed studies, and institutional reports referenced throughout the Beyond HEPA white paper series and supporting papers.

No. 01

Beyond HEPA: Why Agglomeration + ULPA Vacuuming More Effectively Reduces Mold-Related Health Risk

  1. 1.Institute of Environmental Sciences and Technology (IEST). (2016). IEST-RP-CC006.3: Testing Cleanrooms. IEST.
  2. 2.International Organization for Standardization (ISO). (2015). ISO 14644-1:2015: Cleanrooms and associated controlled environments — Part 1: Classification of air cleanliness by particle concentration. ISO.
  3. 3.International Organization for Standardization (ISO). (2016). ISO 14644-3:2005: Cleanrooms and associated controlled environments — Part 3: Test methods. ISO.
  4. 4.National Institute for Occupational Safety and Health (NIOSH). (2014). NIOSH List of Antineoplastic and Other Hazardous Drugs in Healthcare Settings. CDC.
  5. 5.United States Pharmacopeia (USP). (2019). USP General Chapter <797>: Pharmaceutical Compounding—Sterile Preparations. USP.
  6. 6.United States Pharmacopeia (USP). (2019). USP General Chapter <800>: Hazardous Drugs—Handling in Healthcare Settings. USP.
No. 02

Beyond HEPA: Part II — The 0.12–0.3 Micron Gap

  1. 1.Górny RL et al. (2002). Fungal fragments as indoor air biocontaminants. Applied and Environmental Microbiology.
  2. 2.Cho SH et al. (2006). Aerodynamic characteristics of fungal spores and fragments. Atmospheric Environment.
  3. 3.Brasel TL et al. (2005). Detection of airborne Stachybotrys chartarum macrocyclic trichothecene mycotoxins. Applied and Environmental Microbiology.
  4. 4.Oberdörster G et al. (2005). Nanotoxicology: an emerging discipline evolving from studies of ultrafine particles. Environmental Health Perspectives.
  5. 5.Block ML & Calderón-Garcidueñas L (2009). Air pollution: mechanisms of neuroinflammation and CNS disease. Trends in Neurosciences.
  6. 6.Straus DC (2011). The possible role of fungal contamination in human illness. Toxicology and Industrial Health.
  7. 7.World Health Organization (2009). WHO Guidelines for Indoor Air Quality: Dampness and Mould.
  8. 8.Hinds WC (1999). Aerosol Technology: Properties, Behavior, and Measurement of Airborne Particles. Wiley.
  9. 9.EN 1822-1:2019. High Efficiency Air Filters (EPA, HEPA and ULPA).
No. 03

Beyond HEPA: Part III — Clinical Evidence of Harm from Submicron Particulates (<0.3 µm)

  1. 1.ASHRAE Handbook—HVAC Applications, Chapter 62, Ultraviolet Air and Surface Treatment, 2019.
  2. 2.ANSI/ASHRAE Standard 170-2017: Ventilation of Health Care Facilities.
  3. 3.Sehulster L, Chinn RY; CDC. Guidelines for environmental infection control in health-care facilities. Recommendations of CDC and the Healthcare Infection Control Practices Advisory Committee (HICPAC). MMWR Recomm Rep. 2003;52(RR-10):1-42.
  4. 4.CDC (2020). Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Settings.
  5. 5.Environmental Protection Agency. (2018). Residential Air Cleaners: A Technical Summary.
  6. 6.Azimi P, Stephens B. (2013). HVAC filter efficiency and its impact on indoor air quality. ASHRAE Journal, 55(4), 16-25.
  7. 7.Morawska, L., et al. (2020). How can airborne transmission of COVID-19 indoors be minimised? Environment International, 142, 105832.
  8. 8.World Health Organization (2020). Infection prevention and control during health care when novel coronavirus (nCoV) infection is suspected.
  9. 9.Kowalski, W. J. (2009). Aerobiology and its role in the control of infectious diseases.
  10. 10.ASHRAE Position Document on Airborne Infectious Diseases (2020).
  11. 11.Miller, S. L., et al. (2021). Transmission of SARS-CoV-2 by inhalation of respiratory aerosol in the Skagit Valley Chorale superspreading event. Indoor Air, 31(2), 314-323.
  12. 12.Fennelly, K. P. (2020). Particle sizes of infectious aerosols: implications for infection control. The Lancet Respiratory Medicine, 8(9), 914-924.
  13. 13.National Institute for Occupational Safety and Health (NIOSH). (2015). Hierarchy of Controls.
No. 04

Propylene Glycol Fog in Industrial Applications

  1. 1.ACGIH, 2013. Threshold Limit Values for Chemical Substances and Physical Agents. American Conference of Governmental Industrial Hygienists, Cincinnati, OH.
  2. 2.ATSDR, 1997. Toxicological Profile for Propylene Glycol. U.S. Department of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry.
  3. 3.Belsito, D., et al., 2008. A toxicologic and dermatologic assessment of cyclic and non-cyclic terpene alcohols when used as fragrance ingredients. Food and Chemical Toxicology, 46(11), pp. S1-S71.
  4. 4.Burkhart, C.G., 1988. Propylene glycol: The role of the vehicle in contact dermatitis. Cutis, 41(4), pp. 263-264.
  5. 5.Fiume, M.Z., 2001. Final report on the safety assessment of propylene glycol, lauric glycol, myristyl glycol, and palmitic glycol. International Journal of Toxicology, 20(Suppl 2), pp. 23-50.
  6. 6.LaKind, J.S., et al., 1999. A review of comparative inhalation studies of propylene glycol in humans and animals. Inhalation Toxicology, 11(7), pp. 583-605.
  7. 7.National Institute for Occupational Safety and Health (NIOSH), 1976. Criteria for a Recommended Standard: Occupational Exposure to Propylene Glycol. DHEW (NIOSH) Publication No. 76-155.
  8. 8.World Health Organization (WHO), 2002. Propylene Glycol: Concise International Chemical Assessment Document 44. Geneva: WHO.
Submicronix — Precision Air Quality.

Precision indoor air quality for the post-HEPA world. Applying physics and modern aerosol engineering to the environment where patients heal.

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Submicronix does not diagnose, treat, prevent, or cure disease. Content is for informational purposes only.