We perform a wide variety of industrial hygiene sampling, including sampling of air, dust, and liquids to determine exposure to individuals and the environment. We also perform sampling of materials, as part of our building sciences investigations, to determine material composition, evaluate deterioration and aging, and for other purposes.
Air sampling is used for purposes such as determining indoor air quality, exposures experienced by an individual, or to clear an area for re-occupancy after remediation is complete. Bulk material sampling is commonly used to determine the concentration of asbestos or other chemicals in a material in order to develop work practices to protect workers who may contact the material and the environment. As part of our building science practice, we also sample materials for laboratory analysis when diagnosing material failures. Analysis of dust samples allows us to view particulate, such as asbestos, mold or lead, that has settled out of the air onto surfaces over a period of time.
We always sample in accordance with a sampling plan, and evaluate the results statistically. In all instances, a sample is only a small part of the overall environment or material being tested. As the material or environment may not be homogeneous with localized differences, multiple samples are required. The number of samples needed will depend upon the variability between individual samples and total volume of the environment or material being sampled. These determinations are made using sample evaluation methods coming out of the physical sciences. When we sample, we are cognizant of the fact that we are collecting data as part of a scientifically validated sampling plan.
Collecting and evaluating samples according to a plan keeps us from “jumping to conclusions” based upon a single sample, or over a small sampling. This is particularly important when sampling an environment that is continuously changing. For example, mold spore concentrations inside a building change through time, as outside conditions change, but inside levels change more slowly than outdoor levels. This makes evaluation of spore type as important as overall concentrations when interpreting the results. Over the years we have developed sampling protocols that are rugged, including calibration, chain of custody procedures, sampling handling, and worker protection procedures.
Our multi-disciplinary approach helps us with issues such as air sampling for indoor air quality. In these instances, our industrial hygiene staff, with its sampling expertise, collaborates with our engineering staff, with its expertise in airflow, ventilation, and mechanical equipment, to arrive at a sampling plan that reflects prevailing conditions in the building. This collaboration also helps in finding the cause of an indoor air quality problem. Simply collecting air samples does not identify the cause of air quality problems, and in may instances, this requires engineering or building sciences expertise along with the sampling and data interpretation expertise.
We actively participate in committees, such as ASTM D22.07 and D22.08 on development of sampling, evaluation and analytical methods. Several years ago, we took the technical lead in developing ASTM D7390-07 Standard Guide for Evaluating Asbestos in Dust on Surfaces by Comparison Between Two Environments, which provides the statistical procedures to analyze contaminated environments. Shortly after it was published, we used this Guide in the field, in response to a state regulatory agency’s demand for a scientific method of evaluating the extent of a contamination event.
Here are some examples of past projects that illustrate our approach.
- Plaster Study Classifies Wall and Ceiling Plasters in 200 Buildings Built Between 1880 and 1980
- Ventilation Rates Determined by IAQ Studies
- Water Damage Analysis Improves Building HVAC Performance
- Evaluation of Mold Amplification and Moisture Dynamics in University Dormitory
- Odor Investigation
- Material Science