VOC indoor air quality analysis

Office World News, Oct 1999

Indoor air quality (IAQ) investigators are constantly challenged with selecting the appropriate indoor chemical pollutant sampling and analysis methods. This is a critical decision for a successful IAQ evaluation. Indoor air is complex, with anywhere from 30 to 300 individual volatile organic compounds (VOCs) comprising a typical indoor air sample. Most of these contaminants are present at lowlevel concentrations, often in the parts per billion (ppb) or microgram per cubic meter ((mu)g/m3) range. Yet, IAQ studies demonstrate that typical indoor levels of VOCs are between 2 and 1000 times higher than outdoor levels. A variety of VOCs are typically found in indoor air and their sources include construction materials, furnishings, finishes, consumer products, office equipment, occupant activities, and outdoor air. Air Quality Sciences provides sampling media and offers VOC analysis methods based on USEPA protocols. Using a mass spectral database of more than 120,000 individual compounds, AQS provides the sensitivity and broad range identification necessary for successful IAQ evaluations. When developing a successful sampling/analysis strategy, AQS assists IAQ investigators in choosing one of the following methods:

TVOC with All Individual VOCs

Odor and irritation complaints trigger many IAQ investigations and many odor thresholds are in the ppb or ppt range. This comprehensive analysis provides speciation and quantitation of all individual compounds collected in a sample as well as the sum or total VOC (TVOC) value. Using this analysis, the investigator can characterize the wide range of VOCs present and identify the likely sources) of IAQ complaints,

TVOC with Top 20 Individual VOCs

Along with the sum or TVOC value, this analysis identifies and quantifies the 20 individual VOCs that are present in highest concentration in an indoor air sample. Using this analysis, the IAQ investigator can identify the predominant constituents of the TVOC mixture.

TVOC-Only Screening

Using this analysis, the investigator can implement a phased approach to compare general VOC loads in different areas of a building. This screening-level analysis is not recommended for evaluating specific health risks or tracking odors; however, by identifying potential areas of concern, the investigator can then focus on those areas that warrant additional evaluation. In addition, for areas with elevated TVOCs, AQS can retrieve the data from any given samples) and issue a subsequent report speciating and quantifying the individual VOCs present.

Microbial VOCs (MVOCs)

AQS analyzes specific VOCs that are produced by microbial metabolism; this provides a useful indicator of microbial or moisture problems in a building and helps distinguish between chemical and microbial odor sources. This method is recommended when microbial contamination is suspected in areas not accessible for conventional culture-based or spore trap sampling, such as in wall cavities or ventilation system components.

To learn more about VOC analysis and how it can provide answers in your IAQ investigations, call AQS' Customer Service Department at 1 -800-789-0419.