Derrick Crump

Long term diffusive sampling of volatile organic compounds in indoor air

Abstract Measurements of the diffusive uptake rate of six volatile organic compounds (VOCs) by Perkin Elmer type adsorbent tubes packed with Tenax using an exposure period of 4 weeks is described. Environmental chambers are applied to generate appropriate standard atmospheres containing the VOCs of interest to which the diffusive samplers are exposed. The diffusive uptake rates derived show good agreement between tests and are in accordance with results of field trials in non‐industrial indoor air previously reported. Compounds of higher volatility, such as benzene have a considerably lower diffusive uptake rate than compounds such as undecane and 1,2,4‐trimethylbenzene. The diffusive samplers are used to measure the concentration of six VOCs in the living room and main bedroom in 100 homes using a 4 week exposure period. Outdoor concentrations are also recorded at 10 locations. Indoor concentrations exceed those outdoors and are similar to those reported in four other major studies.

Sources and Concentrations of Formaldehyde and Other Volatile Organic Compounds in the Indoor Air of Four Newly Built Unoccupied Test Houses

Concentrations of formaldehyde and other volatile organic compounds (VOCs) were monitored over a 2-year period in the main rooms of four unoc cupied test houses and in the outdoor air. During the construction and furnish ing of the buildings 30 samples of materials were collected and subsequently tested using environmental test chambers to determine amounts of formalde hyde and other VOCs emitted. Concentrations of VOCs in the building were initially high and declined quickly during the first 6 months after construction. Formaldehyde concentrations showed a slower rate of decline with strong sea sonal effects resulting in highest concentrations during summer months. The most important source of benzene and toluene was the outdoor air whereas almost all materials were potential sources of the wide range of VOCs found in the indoor air. Some materials such as paints and flooring are identified as the most important sources of the major VOCs occurring in the indoor air.

Testing for Formaldehyde Emission from Wood-Based Products – A Review

Concern about possible health effects from formaldehyde emitted from wood-based panel products manufactured with urea-formaldehyde and melamine-formaldehyde binding resins has led to the development and increasing use of low emission products. To control the emissions a range of tests has been developed which the wood-based panel industry can use to determine the potential of products to release formaldehyde. This paper reviews laboratory test methods which are based on the extraction of formaldehyde and also the current requirements in European product standards. It further describes the use of chamber tests to measure formaldehyde emission under normal conditions of temperature and humidity. These tests are included in the labelling schemes of some countries and are the subject of a new European standard test method.

The Burning of Incense as an Indoor Source of Volatile Organic Compounds

Incense burning in indoor environments is a common practice in many coun tries and communities in the world. In the present investigation one type of incense was used for the purpose of studying the quality and quantity of emis sions released, both before and during burning with respect to volatile organic compounds including aldehydes. The polycyclic aromatic hydrocarbon (PAH) content and elemenal composition of air particulate matter and ash were also investigated. The study included controlled experiments in an environmental chamber as well as field tests. The results showed the presence of benzalde hyde, linalool, benzyl alcohol, phenethyl alcohol, formaldehyde, and acetalde hyde in the emissions of incense both before and after burning. Incense burn ing produced additional compounds, such as benzene, toluene, and diethyl phthalate. The concentrations of these compounds depended on the time of sampling. No PAHs were detected in air particulate matter after incense burn ing or in the combustion residue. Various elements were detected both in air particulate matter and combustion residue. The results confirm that incense is a potential source of indoor pollution which should be the subject of further study.

Review : Strategies and Protocols for Indoor Air Monitoring of Pollutants

There is an increasing concern about the indoor air quality (IAQ) in non-industrial buildings. The main exposure to air pollutants for most people occurs in indoor environments and this can have an important influence on their health and wellbeing and affect productivity at the workplace. Many environmental parameters need to be considered when assessing the quality of the air in an indoor environment. Any investigation of IAQ requires a clear definition of the objectives of measurement and a strategy for actions required to meet those objectives. This paper outlines the factors that determine IAQ and provides guidance on designing an appropriate sampling strategy, including the selection of methods, for one parameter, organic compounds in the vapour phase. It includes a review of the current state of development of European and international standards for methods of measurement of indoor air pollutants.

A Bench-Top Microchamber Method for Measuring Formaldehyde Emission from Wood-Based Panel Products

In response to concerns about the possible adverse health effects caused by formaldehyde emission from wood-based products, the wood panel products industry has developed and produced lower emission materials over the past 15 years. There is a need for a reliable and inexpensive method in the industry to measure formal dehyde emission from these products that can be used on a routine basis and can provide data comparable to the environmental chamber test prescribed in the Euro pean pre-standard ENV 717-1. A 2.4-litre microchamber test has been developed in the UK, at the Building Research Establishment, as a bench-top method for measuring formaldehyde emission from wood-based materials. Microchamber tests of newly manufactured boards that were preconditioned for 28 days showed good correlation with the steady-state values obtained from the 1-m3 chamber tests determined in accordance with the ENV 717-1 standard. The airflow rate, the ratio of air change to material loading in the chamber and the amount of exposed edges were shown to affect the mea surement of emission rates.

The Use of Diffusive Samplers for the Measurement of Volatile Organic Compounds in the Indoor Air of 44 Homes in Southampton

Diffusive sampling using tube-type adsorbent samplers can be applied to the measurement of volatile organic compounds (VOCs) in the air of homes and outdoors. In the present study samplers packed with Tenax TA have been used to investigate VOCs in the air of 44 homes and at 4 outdoor locations in the Southampton area of the UK as part of a study of the effects of measures for the alleviation of the symptoms of asthma. These measures included installation of mechanical ventilation with heat recovery (MVHR) systems in 20 of the homes. No significant changes in concentrations of 6 VOCs (benzene, toluene, xylene, decane, 1,2,4-trimethylbenzene and undecane) were observed following the MVHR installation. A range of other VOCs found in the homes is identified using mass spectrometry. Twelve different compounds were found to occur as the dominant peak in the chromatogram in one or more indoor air samples, whilst 63 different compounds appeared amongst the 10 biggest peaks.

Assessment of a passive sampler for the determination of aldehydes and ketones in Indoor air

Abstract A diffusive sampler which is commercially available for the determination of formaldehyde in air was investigated for its suitability for the determination of other carbonyl compounds. The potential of the sampler for collecting carbonyl compounds including acetaldehyde, acrolein, pentane‐3‐one and acetone has been demonstrated in the laboratory. When exposed to tobacco smoke acetaldehyde was found to be the most abundant carbonyl compound present. Initial investigations into the uptake rate of the sampler were carried out by exposing the sampler to a known concentration of acetaldehyde in a minichamber and in a 1 m3 test chamber. A complete validation of the sampler has not been undertaken but initial experiments suggest that uptake rate decreases with increasing exposure time and increasing acetaldehyde concentration. For a 72 hour exposure period and an acetaldehyde concentration of 0.07 μg l‐1 the uptake rate of the sampler was 7.0 ml min‐1 with a detection limit of 0.003 μg l‐1. The sampler ...

Reducing Ingress of Organic Vapours into Homes Situated on Contaminated Land

The efficacy of current landfill gas and radon mitigation measures for the prevention of ingress of organic vapours was investigated by the study of four houses situated on contaminated land in North West England. The chemical present in the ground of greatest concern for health due to exposure to vapour in the indoor air was hexachlorobutadiene (HCBD) and the concentration of this compound was used to assess the effectiveness of the remedial measures. A two stage remediation was undertaken. For a house with a solid floor the top surface of the floor was sealed and then for the second stage a fan was used to pressurise the soil gas beneath the house. In a house with a suspended timber floor, extra air bricks were installed to increase ventilation of the floor void and then a fan to further increase air exchange in the void. HCBD in air was monitored by both pumped and diffusive sampling methods. Control houses were also monitored that were not subject to remediation. It is concluded that the remedial measures used for radon protection of a suspended floor have the potential to reduce indoor HCBD concentrations by about 80%, at least in downstairs rooms (where initial levels were highest). The two techniques used for properties with solid floors do not appear to be as effective, and no benefit at all was seen without making allowances for changes in concentration that occurred in the control house over the same period. Further work is required to test the efficacy of the techniques over a longer period and under different circumstances of type of contamination and building characteristics.

Appropriate Sampling Strategies for the Measurement of Formaldehyde in Indoor Air

Active and passive sampling methods are available for the determination of maximum formaldehyde concentrations and average formaldehyde concentrations respectively. The present work compares the performance of an active cartridge type sampler with an impinger method and a diffusive monitor which have previously been used at the Building Research Establishment. Good agreement between the three methods was found in a comparison at two formaldehyde concentration levels. The sampling strategy required to obtain a representative reading of the formaldehyde concentration in an indoor atmosphere was investigated using a commercially available diffusive sampler. An investigation of spatial variation in five rooms suggests that sampling in one location should give a representative reading of the formaldehyde concentration in a room, providing the sampler is not placed near a major source of formaldehyde. An initial investigation of temporal variation in six rooms found that one three day sampling period was suffic...