ISO 16000-20:2014

Overview

ISO 16000-20:2014 - "Indoor air - Part 20: Detection and enumeration of moulds - Determination of total spore count" specifies a harmonized method for air sampling of mould (fungal) spores for microscopy. The standard defines how to collect airborne spores using impactors with a sticky surface and how to determine the total spore concentration (both culturable and non‑culturable) by direct microscopy. It is part of the ISO 16000 series on indoor air quality.

Key topics and technical requirements

• Principle: Air is drawn through an impactor; particles are collected by inertial impaction on a sticky slide or cassette and counted microscopically. No cultivation is performed, so total spore counts are obtained.
• Sampler performance: The sampler cut‑off (aerodynamic diameter with 50% collection efficiency) should preferably be ≤ 1 µm and shall not exceed 2.6 µm to effectively capture mould spores (typical spores ~2–30 µm).
• Apparatus and materials: Impactors with disposable slides/cassettes, vacuum pump, gas volume meter (operating m³), timer, sampling stand, and microscope with 40×/100× objectives (≈400× and 1000× magnification).
• Sampling practice: Typical sampling height is 0.75–1.5 m above the floor. When concentration is unknown, multiple sample volumes (e.g., 50 L, 100 L, 200 L) can be taken to avoid under‑ or overloading slides.
• Reagents and staining: Lactophenol blue staining solution is used for microscopy. Composition per 100 ml: cotton blue 0.5 g; lactic acid (80–85%) 4.0 g; phenol 4.0 g; glycerol 8.0 g; distilled water to 100 ml. Warning: lactophenol blue is toxic - avoid exposure.
• Quality and calibration: Regular volumetric flow and function checks, maintenance and calibration of sampling system, and documented sampling protocol are required.
• Counting and expression: Procedures for direct microscopy counting, calculation and reporting of spore concentrations are specified.

Practical applications

• Assessing indoor air quality and occupant exposure to mould spores in homes, offices, schools and healthcare settings.
• Pre‑ and post‑remediation verification of mould abatement projects.
• Building inspections, environmental health investigations, and epidemiological studies linking dampness/mould to health outcomes.
• Routine monitoring by HVAC/IAQ consultants, occupational hygienists, accredited laboratories, and public health authorities.

Who uses this standard

• Indoor air quality consultants and environmental laboratories
• Occupational and public health professionals
• Building inspectors, remediation contractors and facility managers
• Researchers conducting mould exposure or epidemiological studies

Related standards

• ISO 16000‑16, 17, 18 (other mould sampling and enumeration methods)
• ISO 16000‑19 (sampling strategy for moulds)
• Part of the broader ISO 16000 indoor air series covering sampling strategy and pollutant measurement

Keywords: ISO 16000-20, indoor air, mould detection, spore count, air sampling, impactor, microscopy, lactophenol blue, indoor air quality, mould spores.