Overview - ISO 16000-36:2018 (Indoor air testing for air purifiers)
ISO 16000-36:2018 defines a standard method to evaluate how effectively air purifiers reduce the concentration of culturable airborne bacteria in a controlled test chamber. The method uses nebulized bacterial suspensions, controlled environmental conditions and microbiological sampling to calculate a bacterial reduction rate (expressed in percent). Tests are intended for air purifiers commonly used in single-room spaces.
Key topics and technical requirements
- Test principle: Compare culturable bacterial concentrations after nebulizing a test suspension with and without operating the air purifier; account for natural decay and chamber homogeneity.
- Test chamber: Airtight, low-emission construction (e.g., stainless steel); minimum volume ≥ 8 m3 (typical 15–30 m3); HEPA, air conditioning and decontamination capability recommended. Annex A provides chamber examples.
- Environmental conditions: Default test conditions are (23 ± 2) °C and (50 ± 5) % relative humidity (per ISO 16000-9:2006); any alternative conditions must be documented.
- Aerosol generation: Nebulizer producing particles in the ~0.05 µm to 5 µm range to generate individual bacterial aerosols.
- Sampling and analysis: Use impaction samplers (impactors) to collect culturable bacteria on agar and report colony forming units (CFU). Upper detection limits for a 300-hole sampler are approximately 1.6 × 10^4 CFU/m3 (100 L sample) or 3.2 × 10^4 CFU/m3 (50 L sample).
- Test sequence: measure background concentration → nebulize test bacteria → measure initial concentration → measure concentration after defined time with/without purifier → calculate natural decay and bacterial reduction rate.
- Safety and quality: Tests must be carried out by trained staff in microbiological safety cabinets (class II). The standard warns about handling facultative pathogens (e.g., Staphylococcus aureus) and requires appropriate containment, decontamination and quality assurance procedures.
Applications - who uses this standard
- Air purifier manufacturers - performance verification and product development.
- Independent test laboratories - standardized test reports for certification and comparison.
- Regulatory bodies and procurement teams - evidence-based selection of air cleaning devices for schools, offices and healthcare spaces.
- Indoor air quality (IAQ) researchers - reproducible methods for studying microbial removal.
- Certifiers and third-party auditors - consistent benchmarks for marketing claims and compliance.
Related standards and references
- ISO 16000 series (indoor air standards) - broader context for indoor air testing.
- ISO 16000-9:2006 - chamber methods for VOC emission testing (used for temperature/humidity guidance).
- ISO 3696 - water for analytical laboratory use (relevant to media/preparation).
Keywords: ISO 16000-36:2018, indoor air, air purifier testing, culturable airborne bacteria, test chamber, bacterial reduction rate, nebulizer, CFU, impaction sampling.
