Air quality problems encountered in different environments (e.g. ambient, indoor & industrial) can be very different in nature or can be very similar. For example, occurrences of odours, which play a major role in most air quality complaint cases, can originate from any of these environments from similar or widely different volatile organic compounds (VOCs). Through many years of extensive research, CASSEN Testing Laboratories has developed various techniques to characterize odour-related air quality problems attributed to volatile organic compounds. Examples of various odour-causing air quality problems are shown throughout this document.
Odour complaints including transient odour
Bad air quality complaints due to VOCs released:
Migration of VOCs into buildings through:
Various Air Quality Problems Solved by CASSEN Testing Laboratories
The following examples have been chosen to highlight the diverse applications and power of the open characterization technique for solving air quality problems. The samples discussed were analyzed using the adsorption/flash thermal desorption technique coupled with gas chromatography/mass spectrometry in accordance with a number of referenced methods. Typically, samples submitted include indoor and outdoor air samples, industrial plant air, bulk materials, exhaust emissions and industrial process emissions. The technique is highly useful in identifying a number of air quality problems such as:
The above sample was taken from a municipal wastewater treatment facility where offensive odour was observed in the aeration basin during sludge treatment. Many odorous compounds were detected in this area, including volatile fatty acids, organic sulphides, amines, phenolic compounds and aldehydes. Other compounds found included aromatic and aliphatic hydrocarbons, chlorinated compounds and ketones. Odour in this location was apparently caused by the combination of many classes of organic compounds including those with very low odour thresholds.
Over a few hundred compounds were detected such as:
Office workers complained of a transient odour inside a one-storey commercial building where no chemicals were used. Health effects included nose and throat irritation, headache and nausea. On the day of sampling, no odour was observed.
Analytical results from the samples taken in various locations of the office showed a large number of aliphatic hydrocarbons and aromatic hydrocarbons. Light alkanes, low molecular weight aldehydes and 1,3-butadiene were detected. In addition, methyl tert-butyl ether (MTBE) was found to be a major compound. MTBE is a flammable liquid with an unpleasant odour and is used in some regions as an additive for unleaded gasoline to achieve more efficient burning. The symptoms of exposure agreed with the health effects experienced by the workers. The profile suggests exhaust fumes from vehicles temporarily stalling outside the building while the drivers entered the building were responsible for the transient odour.
A bottle containing an unknown liquid was found inside an apartment building. When opened, it was found to have a very pungent odour. Due to health concerns, the bottle was submitted for testing A headspace sample was sampled onto a sorbent tube and the component was analyzed by thermal desorption/GC/MS.
The analytical results showed a large amount of phenolic compounds, including alkyl and chloro-substituted phenols. The major organic compounds identified in this sample are presented below:
The content of the sample appeared to contain Creolin Disinfectant, which contains ingredients of carbolic oil and substituted phenols. Carbolic oil is also known as carbolic acid, middle oil or liquidified phenols. It is one of the fractions from coal tar distillation. The presence of large amounts of phenolic compounds and compounds such as pyridines will undoubtedly impart a strong and unpleasant odour when this material is used.
Odour concerns from a plastic extrusion process in a manufacturing facility resulted in the need to determine the content of emissions. Samples were collected during the extrusion process and submitted for analysis. A large number of volatile organic compounds were detected and the major ones are shown below:
In another plastic extrusion process, in addition to a large number of aliphatic hydrocarbons, a number of compounds were detected and their respective sources are presented below:
Subsequent to workers’ complaints of odour during the curing of brake parts, thermal desorption tubes were used to investigate the emissions in the areas surrounding the curing oven. The analytical results showed the presence of the following major airborne organics:
The odour was mainly attributed to a combination of the above-mentioned compounds, especially phenol and alkenes.
A large amount of fuel oil seeped into the basement of a home from a storage tank. The top chromatogram of the indoor air sample taken from the basement of the home shows typical low molecular weight VOCs (alcohols, ketones, hydrocarbons, etc. before 20 minutes) found in indoor environments. The large hump of VOCs after 25 minutes in the chromatogram are higher molecular weight aliphatic and aromatic hydrocarbons which illustrates a strong correlation with the fuel oil from the storage tank. Clear confirmation of chemical contamination of indoor air from fuel oil infiltration from contaminated soil can be achieved.