ASTM D7391-20 PDF

Full title and description

Standard Test Method for Categorization and Quantification of Airborne Fungal Structures in an Inertial Impaction Sample by Optical Microscopy — ASTM D7391-20. This test method specifies optical‑microscopy procedures to identify, categorize by morphological type, and enumerate fungal structures collected on inertial impactor sample traces (slit or circular) and to report results as fungal structures per sample and per cubic metre of air.

Abstract

ASTM D7391-20 provides a standardized, microscopy‑based procedure for examining deposits on inertial impaction air samples to categorize fungal structures (from fine taxonomic groupings such as genus up to phylum) and quantify them as counts/sample and counts per cubic metre. The method includes separate counting procedures for slit and circular impaction samples, describes reporting units and limitations (for example particle obscuration and sample coverage), and is limited to laboratory analysis of collected samples (sampling and interpretation are outside its scope).

General information

• Status: Active (current edition approved March 15, 2020).
• Publication date: 15 March 2020.
• Publisher: ASTM International.
• ICS / categories: 07.100.99 (Other standards related to microbiology).
• Edition / version: D7391-20 (current revision; previous editions include D7391-17 and original 2009 adoption).
• Number of pages: 13.

Scope

This test method provides direct‑microscopy procedures to analyze the deposit on an inertial impaction sample, to categorize fungal structures by morphological type (from genus-level examples such as Cladosporium up to phylum level such as basidiospores), and to enumerate fungal structures using two procedures (one for slit impaction traces and one for circular impaction traces). The method applies to impaction air samples collected with known air volumes and to blank impaction samples; enumeration results are reported in fungal structures per sample (fs/sample) and fungal structures per cubic metre (fs/m3). The method addresses only sample analysis — sampling technique and interpretation of environmental significance are explicitly outside its scope.

Key topics and requirements

• Direct optical microscopy of inertial impaction sample traces (slit and circular formats).
• Categorization of fungal structures by morphological type (taxonomy level flexible: genus → phylum).
• Enumeration procedures and calculations that produce results in fs/sample and fs/m3.
• Quality controls including use of field blanks and percentage of trace counted considerations.
• Limitations and reporting requirements (particle obscuration, sample coverage, and dependence on spore size and sampled air volume).
• Precision statement established by an interlaboratory study (Research Report RR:D22‑1037 supports the method’s precision assessment).

Typical use and users

Used by environmental‑microbiology and indoor‑air quality laboratories, industrial hygienists, environmental consultants, public‑health investigators, building inspectors, HVAC and mould‑remediation professionals, and researchers studying bioaerosols. Typical applications include routine laboratory analysis of impactor samples collected during indoor air investigations, baseline surveys, remediation verification (laboratory counting only), and research on airborne fungal distributions.

Related standards

Closely related ASTM standards and practices include: ASTM D7788 (practice for collection of total airborne fungal structures via inertial impaction methodology) and ASTM D1356 (terminology relating to sampling and analysis of atmospheres). Users commonly consult interlaboratory and precision guidance (E691/E177 practices) when applying or validating D7391.

Keywords

bioaerosol, fungal, fungal structures, fungi, fungus, impaction, impactor, indoor air quality, mold, mould, spore, spores, optical microscopy, enumeration, fs/m3.

FAQ

Q: What is this standard?

A: ASTM D7391-20 is a test method that defines how to categorize and count airborne fungal structures collected on inertial impaction samples using optical microscopy.

Q: What does it cover?

A: It covers laboratory procedures for identifying fungal structures by morphology and enumerating them on slit and circular impactor sample traces, and how to report results (fs/sample and fs/m3). It does not cover the sampling equipment selection, sample collection protocols, or interpretation of environmental/health significance.

Q: Who typically uses it?

A: Environmental and indoor‑air labs, industrial hygienists, remediation contractors, building inspectors, public‑health investigators, and researchers performing bioaerosol analyses.

Q: Is it current or superseded?

A: The D7391-20 edition was approved 15 March 2020 and is published as the current active edition. It supersedes earlier editions (for example D7391-17/e1 and the original adoption). Users should verify with ASTM for any later revisions.

Q: Is it part of a series?

A: It is part of the ASTM D22 committee’s body of air‑quality and bioaerosol standards and is commonly used alongside related D22 documents (for sampling practice, terminology, and validation/precision reports).

Q: What are the key keywords?

A: bioaerosol, fungal structures, spores, impactor, optical microscopy, enumeration, indoor air quality, mold, fs/m3.