ISO INTERNATIONAL STANDARD 8756 First edition 1994-01-15 Air quality --- Handling of temperature, pressure and humidity data Qualité de I'air -- Traitement des données de temperature, de pression et d'humidite ISO Referencenumber ISO8756:1994(E) ISO8756:1994(E) Foreword IsO (the International Organization for Standardization) is a worldwide of preparing International Standards is normally carried out through IsO technical committees.Each member bodyinterested in a subjectfor whicha technical committeehas been established has the right tobe and non-governmental, in liaison with IsO, also take part in the work. IsO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated tothe memberbodies forvoting.Publication as an International a vote. International Standard ISO 8756 was prepared by Technical Committee ISO/TC 146, Air quality, Subcommittee SC 4, General aspects. AnnexA of this International Standard isfor informationonly OS! 1994 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced microfilm, without permission in writing from the publisher. International Organization for Standardization Case Postale 56· CH-1211 Geneve 20· Switzerland Printed in Switzerland ii INTERNATIONALSTANDARDISO IS08756:1994(E) Air quality Handling of temperature, pressure and humidity data 1 Scope plants (e.g.nearblastfurnaces),changesmaybevery sudden and large. This International Standard describes procedures for adjusting air quality measurements for changes in The effect of change in humidity will be different for temperature, pressure and humidity during the sam- different methods of air quality measurement and is pling period. It also specifies the reference conditions not merely a correction for the volume of air sampled. of temperature, pressure and humidity to be used For the effect of humidity, it is essential to refer to the when reporting the results. specific air quality measurement method. The procedures and reference conditions are appli- 2.1.2 Sampling period of up to 15 min duration cable to air quality measurement methods and apply to measurements made in ambient and workplace Atmospheric temperature, pressure and humidity are atmospheres and to the measurement of stationary unlikelytochange significantly in any15min period source emissions. and corrections for changes are therefore unneces- sary. 2 Procedures for adjustment of air in this case, the atmospheric temperature and press- ure (where relevant, the absolute or relative humidity) quality measurements for changes in should be noted at the time of sampling. atmospheric pressure, temperature and humidity during the sampling period 2.1.3 Sampling period of up to 1 h duration 2.1 Ambient and Workplace Atmospheres Atmospheric pressure is unlikely to change greatly during a 1 h sampling period, but the temperature may change significantly during normal weather con- 2.1.1 General ditions. Atmospheric temperature, pressure and humidity may In this case, atmospheric pressure should be noted all change during the sampling period, which may be once during the sampling period, the temperature of a duration of several minutes or several weeks, measured at the start and finish of sampling and the depending on the location at which the air quality mean value recorded. Where relevant, the absolute measurements are made (workplace or ambient) and or relative humidity should be noted once during the the purpose for which they are required. Pressure and sampling period, preferably at the middle of the pe- absolute humidity change slowly, but temperature riod. and relative humidity changes may be much more sudden. For example, a daily change in pressure may 2.1.4 Sampling period of up to 12 h duration be of the order of approximately 4 000 Pa taking place fairly smoothly at a rate of 200 Pa/h.Temperature