Patients with forms of aspergillosis like ABPA can be highly allergic to fungal and many other airborne allergens. For some, relief can be found by ensuring the levels of airborne allergens in the home are as low as possible—this means removing as much dust as possible and removing sources of dust in the home.

Fungal spore fragments can be extremely small so air filters and vacuum cleaners have to have HEPA-grade filtration systems in order to be effective. NB there are some air cleaning systems that do not use filtration as a means to remove particles, instead they use heat (see bottom of page).

For those that use HEPA filters it is important that the correct grade of HEPA filtration is provided:

HEPA (High-Efficiency Particulate Air) filters are classified into different grades based on their filtration efficiency. The most commonly used classification is from ISO 29463 (based on EN 1822-1), which divides HEPA filters into E (Efficiency), H (High Efficiency), and U (Ultra-Low Penetration Air – ULPA) categories.

HEPA Filter Grades and Their Uses

Filter Class Efficiency (MPPS – Most Penetrating Particle Size, ~0.1-0.3 μm) Common Applications
E10 ≥ 85% Pre-filters in air purification systems
E11 ≥ 95% Air conditioning systems, HVAC filters
E12 ≥ 99.5% General air filtration, residential HEPA vacuum cleaners
H13 ≥ 99.95% Medical facilities, clean rooms, operating theaters
H14 ≥ 99.995% Pharmaceutical industry, laboratories, high-end medical applications
U15 ≥ 99.9995% Semiconductor manufacturing, critical research labs
U16 ≥ 99.99995% Nuclear and hazardous material containment
U17 ≥ 99.999995% Highly sensitive biological or radioactive environments

Key Uses of Different HEPA Grades

  1. E10-E12: Used in standard HVAC systems, air purifiers, and vacuum cleaners.
  2. H13-H14: Common in hospitals, clean rooms, and biosafety labs where high air purity is needed.
  3. U15-U17 (ULPA): Found in pharmaceutical manufacturing, semiconductor industries, and nuclear facilities.

For medical conditions like ABPA, HEPA H13 or H14 filters are recommended in home air purifiers and hospital settings to reduce airborne Aspergillus spores.

Heat-based filtration

Some domestic air purifiers use heat-based filtration to neutralize airborne contaminants. These typically work by heating air to a high temperature to kill bacteria, viruses, mould spores, and other pathogens before cooling them down and releasing them into the room.

Types of Heat-Based Air Cleaners

  1. Thermodynamic Sterilization (TSS) Air Purifiers

    • Uses a ceramic core heated to ~200°C (392°F) to destroy airborne microorganisms.
    • No filters, so there’s no need for replacements.
    • Example: Airfree air purifiers (popular in allergy-sensitive households).

  2. Hybrid Heat & Filtration Systems

    • Combines heat sterilization with HEPA filters or activated carbon.
    • Example: Some high-end medical-grade air purifiers integrate thermal disinfection.

Advantages

✔ Kills mold, bacteria, and viruses rather than just trapping them.
✔ No filter replacements (TSS models).
✔ Silent operation (as some don’t use fans).

Disadvantages

❌ Limited particle filtration—doesn’t remove dust, pet dander, or allergens like a HEPA filter does.
❌ Slower purification compared to fan-driven systems.

Best Use Cases

  • Allergy and asthma sufferers (e.g., ABPA) who want a maintenance-free solution.
  • People sensitive to mold and bacteria in humid environments.
  • Homes with immunocompromised individuals needing sterile air.

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