Veronica M. Brown

Exposure to air pollutants in English homes.

BRE has conducted a national representative survey of air pollutants in 876 homes in England, designed to increase knowledge of baseline pollutant levels and factors associated with high concentrations. Homes were monitored for carbon monoxide (CO), nitrogen dioxide (NO2), formaldehyde and volatile organic compounds (VOCs). In the majority of the homes, concentrations of the measured pollutants were low. However, some homes have concentrations that would suggest a need for precautionary mitigation. Those factors that are most likely to lead to exposures of concern in homes are identified as gas cooking (for CO and NO2), the use of unflued appliances for heating (for CO and NO2), emissions from materials in new homes (for total VOC (TVOC) and formaldehyde), and painting and decorating, with a significant increase in risk suspected to exist where there is not a place to store materials away from the living space (for TVOC). It is noteworthy that seasonal effects on CO and NO2 were largely due to indoor sources. This would need to be considered when interpreting time series studies of the effect of outdoor air pollution on health. It is also of some significance that the critical factors are related much more to sources than to ventilation: source control is therefore, as would be expected, the most appropriate approach to reducing the risk of hazardous exposure to air pollutants in homes.

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.

Development and Application of a Protocol for the Assessment of Indoor Air Quality

The main exposure to air pollutants for most people occurs in indoor environments and this can have an important influence on their health and well-being and affect productivity at the workplace. BRE has prepared a protocol for the measurement of key parameters to undertake an indoor air quality (IAQ) assessment. The measurements required depend upon the objectives and therefore the design of an appropriate strategy is an important first stage in any IAQ assessment. This paper summarises the recommended protocol and reports its evaluation by a study of 10 homes and 10 office buildings. The IAQ protocol was generally well accepted by occupants. There are problems with evaluating the significance of the measurements of some parameters because of a lack of relevant air quality guidelines and data about concentrations that normally occur in buildings. The BRE protocol can be used as guidance by specialists undertaking an IAQ assessment and by building owners/managers concerned about IAQ.

Personal exposure to benzene and the influence of attached and integral garages.

Benzene is an air pollutant that is a recognised human carcinogen. An air quality standard has been established for ambient air in the UK to reduce the popula tions exposure. It has been estimated that about 70% of benzene emissions to air in the UK come from petrol vehicles. A number of studies, including the Avon Longitudinal Study of Pregnancy and Childhood in the UK, have found that benzene concentrations in homes with attached or integral garages tend to be higher than in those without such garages. The present paper reviews these studies and reports a detailed investigation of five homes with either an attached or an integral garage. Indoor and outdoor locations were monitored using diffusive sampling to determine the average benzene concentration over approximately 28 days each month for 18 consecutive months (June 1998-November 1999). For one of these homes, ten years of data had shown the indoor benzene concentration to be con sistently higher than outdoors. Personal exposure monitoring of one adult in this home showed that the benzene concentration in the main bedroom was a better predictor of personal exposure than the concentration outdoors. In the homes where a car was regularly parked in the garage, 18-month aver age benzene concentrations of up to 101.3 μgm 3 were measured in the garage, which is more than six times the ambient air quality standard for benzene (16.25 μgm3 running annual average). Mean benzene values in all cars and most of the garages studied exceeded the benzene standard. Mean benzene concentrations in the room above the garage ranged from 3.7 μgm3 in one home, where the car was rarely parked in the garage, to 39.9 μgm3 in another home where a car with high benzene emissions was parked in the garage for six of the 18 months monitored. The mean benzene concentration in the room above the garage in this latter home was nearly 2.5 times the ambient air standard. The study demonstrates that there is a potential for people to have a higher exposure to benzene as a result of living in a home with an attached or integral garage. An understanding of routes of personal exposure is important to devel op effective policies to reduce risks to health.

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...

Levels of Indoor VOCs in Workplaces in a Polluted Urban Area of London

To date there have been few published investigations on the levels of indoor volatile organic compounds (VOCs) in workplaces in polluted urban areas in the UK. The present investigation was carried out in a non-smoking and naturally-ventilated office building situated along one of the most polluted roads in London in conjunction with the Dispersion of Air Pollutants and their Penetration into the Local Environment (DAPPLE) 2003 field campaign. The results from the measurements taken for indoor VOCs in offices where smoking was prohibited are reported. The concentrations of hexanal, m-, p-xylene, styrene, toluene and total VOCs (TVOCs) are presented and discussed. Other VOCs, in addition to those primarily selected for analysis, were also recorded.