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D1739-98 – Standard Test Method Technical Guide
ASTM D1739-98 (Reapproved 2017) provides a straightforward, standardized procedure for collecting and measuring settleable particulate matter, or dustfall, from the ambient atmosphere. Designed for long-term trend analysis, this passive method specifies the use of standard cylindrical containers exposed for approximately 30 days. The collected material is subsequently fractionated into water-soluble and water-insoluble components, with results reported in grams per square metre per 30-day period [g/(m²·30 d)].
🛠️ Apparatus and Site Specifications
The standard requires an open-topped cylinder with a minimum diameter of 150 mm (6 in.) and a height no less than twice its diameter. This specific geometry minimizes re-entrainment of collected particles. Containers are prepared and sealed in the laboratory, then deployed at carefully selected sites to avoid contamination from specific local sources. Upon completion of the nominal 30-day sampling period, the containers are resealed and returned to the laboratory for analysis.
⚙️ Collection, Sieving, and Gravimetric Measurement
Once retrieved, the container contents are washed and processed. The test method defines settleable particulate material as particles small enough to pass through a 1-mm sieve (per Specification E11) that settle under their own weight. The material is then separated into water-soluble and water-insoluble fractions. The mass of each fraction is determined gravimetrically. Any material that enters the container but did not settle from the ambient air is considered an interferent.
⚡ Critical Limitation: This test method is inappropriate for industrial hygiene use except where other more specific methods are also used. It is a crude and non-specific tool intended for long-term ambient studies, not for compliance with workplace exposure limits or assessment of specific localized sources.
| 🟦 Specification Parameter | 📏 Required Value |
|---|---|
| Container Diameter | ≥ 150 mm [6 in.] |
| Container Height | ≥ Twice the Diameter |
| Analysis Sieve | 1 mm (E11 Specification) |
| Exposure Duration | ~30 days |
| Report Units | g/(m²·30 d) |
📊 Significance, Reporting, and Interpretation
The primary advantage of this test method is its extreme simplicity. It requires very little investment in equipment and can be performed without a large technically-skilled staff, making it highly suitable for regional deposition surveys and studying long-term trends. The result is expressed as the combined mass of soluble and insoluble material per unit area per standard 30-day month, providing a consistent metric for comparing dustfall rates across different locations and time periods.
✅ Recommended Application: The test method is ideal for establishing baseline environmental data and monitoring secular changes in particulate deposition. Its robust and passive nature allows for widespread deployment with minimal operational costs.
| 🧪 Measured Component | 📋 Description |
|---|---|
| Water-Soluble Matter | Dissolved salts and ionic compounds |
| Water-Insoluble Matter | Mineral dust, soot, and organic debris |
❓ Frequently Asked Questions
🔍 What is the primary purpose of ASTM D1739-98?
It is designed to measure the “dustfall” or settleable particulate matter rate in ambient air over a standard 30-day period, providing data primarily for long-term trend analysis rather than short-term source evaluation.
⚡ What are the key limitations of this test method?
It is not appropriate for determining dustfall rates in small areas affected by specific sources. It is also unsuitable for industrial hygiene applications unless supplemented by more specific methods, given its crude and non-specific nature.
💡 How are the results of the collection expressed?
The total mass of dustfall, comprising both water-soluble and water-insoluble fractions, is combined and reported as grams per square metre per 30-day period, or g/(m²·30 d).
📌 What are the specific dimensions required for the collection container?
The apparatus must be an open-topped cylinder with a diameter of at least 150 mm [6 in.] and a height of at least twice its diameter to properly capture and retain settling particles.