RESEARCH REPORT 127 - HSE: Information about …

1 HSE Health & Safety Executive Measurement and modelling of combustion products from flueless gas appliances Prepared by BRE Environment for the Health and Safety Executive 2004 RESEARCH REPORT 127 HSE Health & Safety Executive Measurement and modelling of combustion products from flueless gas appliances Stuart Upton, Dr David Ross and Bridget Pierce BRE Environment Division Bucknalls Lane Garston Watford WD25 9XX Concentrations of combustion products emitted from a range of flueless gas appliances have been measured in a chamber capable of being ventilated in a controlled and reproducible manner, including worst case simulations that would be experienced in extremely air-tight rooms. This enabled subsequent prediction of the likely concentration of combustion products for a range of ventilation provisions, room sizes and potential uses of the flueless gas appliances.

2 In the absence of UK indoor air quality guidelines, the concentrations of combustion products emitted have been compared with the World Health Organisation (WHO) guidelines and HSE Occupational Exposure Standards (OES). When ventilation in the chamber was through purpose-provided open area ventilation (as specified by the appliance manufacturer or BS 5440-2: 2000), levels of all combustion products were elevated, with carbon dioxide (CO2) in particular reaching concentrations much higher than the HSE OES value. Even when mechanically provided with higher and more typical levels of ventilation, concentrations of CO2 in the chamber higher than the value set for the HSE Occupational Exposure Standard (OES) were measured. modelling using the BREEZE program showed that the concentration levels set for the HSE Short-Term Exposure Limits for CO2 and carbon monoxide (CO) will rarely be exceeded within typical UK dwellings.

3 However, those for the HSE eight-hour OES for CO2, and the WHO guideline concentrations for CO are much more likely to be exceeded in situations where there is prolonged use of a flueless appliance. For nitrogen dioxide (NO2), it is very unlikely that the HSE limits will be exceeded in dwellings, but the WHO guideline concentrations will be commonly exceeded. The current guidance given within BS 5440:2 is for the installation of purpose-provided open-area ventilation of at least 100 cm2 in rooms where flueless heating appliances may be fitted. The build up of pollutants to concentrations in excess of the recognised HSE and WHO guidelines was not prevented by the purpose-provided ventilation currently required within BS 5440-2. This could be exacerbated as dwellings are made more airtight to meet the increasingly strict requirements of the Building Regulations, unless other ventilation provisions in homes (windows, fans, passive stacks etc.)

4 , as required under the Building Regulations are also used in practice. This REPORT and the work it describes were funded by the Department of Trade and Industry (DTI) and the Health and Safety Executive (HSE). Its contents, including any opinions and/or conclusions expressed, are those of the authors alone and do not necessarily reflect DTI or HSE policy. HSE BOOKS Crown copyright 2003 First published 2003 ISBN 0 7176 2704 7 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means (electronic, mechanical, photocopying, recording or otherwise) without the prior written permission of the copyright owner. Applications for reproduction should be made in writing to: Licensing Division, Her Majesty's Stationery Office, St Clements House, 2-16 Colegate, Norwich NR3 1BQ or by e-mail to ii FOREWORD BY DTI/HSE The use of flueless gas appliances, for domestic cooking and heating purposes, has been widespread over many years, and continues to be so.

5 Such appliances are usually covered by specific product or installation standards, and all new appliances are subject to certification by an independent Notified Body against compliance with the essential safety requirements of the Gas Appliances Directive (enacted by the Gas Appliances (Safety) Regulations 1995 (GASR)). The Certification process includes an assessment of the manufacturer s installation instructions, and the appliances are currently being installed to these instructions and British Standards installation specifications. However, questions have arisen over the possible health risks from the combustion products emitted by such appliances in normal operation. In order to start to assess any possible risks posed by flueless gas appliances, Information was required on the type and concentrations of the emission products. The Department of Trade and Industry (DTI) and HSE, therefore, agreed to co-sponsor the work of BRE, reported here.

6 It should be noted that the appliances were chosen at random as representative of their type, and the work should not be construed as a REPORT on individual manufacturers appliances. The DTI have responsibility for ensuring only safe products may be placed on the market, in this instance under the GASR, while HSE has responsibility for appliance installation requirements under the Gas Safety (Installation and Use) Regulations 1998. Therefore, the question of the suitability of the use of flueless gas appliances is a matter of joint responsibility. To this end, DTI/HSE have also been assessing Information obtained in a previous study*1, carried out by Advantica Technologies Ltd for HSE. This and the present (BRE) work has been carried out against a background of proposed changes to HSE occupational exposure standards for certain combustion products and an increasing awareness of indoor air quality issues.

7 Currently, there are no UK published standards for domestic indoor air quality, but guidelines are being considered by the Department of Health (DoH) and its advisory committees. In the absence of published Information , advice was requested from the DoH Advisory Committee on Medical Effects of Air Pollutants (COMEAP), as to acceptable indoor air levels for the pollutants emitted from the flueless gas fires examined in the previous study. The Advisory Committee have recommended comparing the level of pollutants with guidelines and standards published by the World Health Organisation (WHO)*2 and the Expert Panel on Air Quality Standards (EPAQS)*3, 4. The REPORT references the WHO guidelines*5, but comparison is also made with HSE occupational exposure standards where no WHO guideline is published. It is important to stress that, while pointing to a possible health effect, the raw comparisons provide no indication of risk level or significance.

8 It should be noted that some manufacturers dispute the validity of the previous study, pointing out that they represent a worst case scenario that would seldom, if ever, be encountered in practice. Similar arguments may be directed to parts of this study, which as the REPORT acknowledges, includes some experiments simulating emissions from appliances into extremely airtight rooms and appliances operating in fault modes. However, the basic rationale for this approach is to provide sufficient Information to subsequently enable likely concentrations of combustion products to be predicted for a iii wide range of ventilation provision, room size and potential use of the gas appliances. Such predictions can only be based on work where all the parameters can be controlled, in a test chamber as used in this case. This REPORT contains examples of predictions covering those appliances with the worst and typical emission rates for the main combustion products studied.

9 Care should be taken in interpreting these predictions and applying them to the other appliances, as the operating period on which a particular prediction is based may not be representative of the normal period of use of those other appliances. While acknowledging the limitations of this laboratory study, DTI/HSE are publishing this REPORT in the public interest, as a contribution to the wider discussion on product and installation standards for flueless gas appliances. As part of this debate, DTI/HSE are working closely with relevant bodies the British Standards Institution (BSI), to ensure that the implications of this work are explored in developing future standards and guidelines for flueless gas appliances. *1 Hill RW and Marks S, Flueless gas fires concentration of carbon monoxide, carbon dioxide and nitrogen dioxide, and particulate level produced in use, HSE RR 23/2004.

10 *2 World Health Organisation. Air Quality Guidelines for Europe. Second Edition. WHO Regional Publication, European Series, No 91. Copenhagen: WHO Regional Office for Europe, 2000. *3 Department of the Environment. Expert Panel on Air Quality Standards. Carbon Monoxide. London: HMSO, 1994. *4 Department of the Environment. Expert Panel on Air Quality Standards. Nitrogen Dioxide. London: HMSO, 1996. *5 World Health Organisation . (1999). Air Quality Guidelines. WHO, Geneva. From [The guideline levels from this reference: CO 8-hour mean of 9 ppm and NO2 1-hour mean of 105 ppb; are slightly different from those quoted by COMEAP from reference *2: CO 8-hour mean of 10 ppm and NO2 1-hour mean of 100 ppb. The differences arise from the conversion of the guideline values, which are quoted in microgramme/m3 to ppb at standard temperatures of either 20oC or 25oC.]