ASTM D7391 Standard Test Method for Categorization and Quantification of Airborne Fungal Structures in an Inertial Impaction Sample by Optical Microscopy

ASTM D7391 Introduction

The ASTM D7391 standard method allows ASTM Committee D22 on Air Quality to perform analysis of fungal structures obtained through inertial impaction. The standard methodology was initially released in 2009, with subsequent updates occurring in 2017 and 2020, through which it establishes consistent methods for fungal particle observation and counting under optical microscopy. Assessing indoor air quality becomes more effective through this method when mold contamination poses a risk in indoor spaces.

ASTM D7391 Test Method

ASTM D7391 Equipment and Sample Preparation

Results and Interpretation

The enumeration results are influenced by spore size and the presence of particulate matter on the sample, together with the percentage of analysis and air volume measurement. The method underlines that analysts have a substantial impact on results because identification and counting require subjective interpretation. 

Tests Related to ASTM D7391

ASTM D7391 is related to other standards, including ASTM D1193 specification for reagent water and ASTM E691 for conducting and determining the precision of a test method.

Use of ASTM D7391 Testing in Various Industries

The test method finds extensive application throughout various sectors that monitor indoor air quality, such as environmental consulting, building maintenance, and the public health sector. The measurement technique helps healthcare facilities determine mold contamination levels for proper remediation work and regulatory compliance purposes. 

Common Challenges and Troubleshooting in ASTM D7391 Testing

The implementation of ASTM D7391 faces difficulties because microscopic examinations are subjective, analyst fatigue occurs, and various sample collection techniques lead to inconsistencies. Lab applications of ASTM D7391 require quality control implementation through analyst training programs and inter-laboratory comparisons to deliver reliable, consistent results.