This International Standard is applicable to transportable, mobile or installed assemblies intended to measure environmental air kerma rates or air absorbed dose rates from 30 nGy⋅h –1 to 30 µGy⋅h –1 or ambient dose equivalent rates from 30 nSv⋅h –1 to 30 µSv⋅h –1, or air kerma or air absorbed dose from 10nGy to 10mGy, or ambient dose equivalent from 10nSv to 10mSv, due to photon radiation of energy between 50 keV and 7 MeV. The measurable range of dose and dose rate can be extended by agreement between the purchaser and the manufacturer. This extension may be realized by combining more than one detector, for example NaI(Tl) scintillator and ionization chamber. For most environmental applications, instruments may measure over a more limited energy range of 80 keV to 3 MeV. NOTE1 80 keV to 3 MeV has been chosen to cover the energies of the chief environmental and man-made radio-nuclides that contribute to the environmental dose. The term “dose?? used in this standard means the quantity, air kerma, air absorbed dose, and ambient dose equivalent, that the instrument is intended to measure. If the assembly is to be used to measure these quantities in the area surrounding a nuclear reactor producing 6 MeV radiation from the 16N isotope, it will be necessary to determine the response at this energy. An absorbed dose in air, which uses the same unit, Gy, as air kerma can be taken to have the same numerical value as air kerma under the condition of electron equilibrium. Passive devices such as Thermo-Luminescence Dosemeter (TLD), Optically Stimulated Luminescence (OSL) Dosemeter or Glass Radio-Photo Luminescence (RPL) Dosemeter are not covered by this standard. Installed assemblies should be capable of operating continuously. This standard does not provide for the measurement of beta and neutron radiation. The equipment covered by this standard comprises a detector assembly and processing circuits, which may be connected together either rigidly or by means of a flexible cable, or incorporated into a single assembly. The equipment assembly may also include circuits for displaying readings, alarms and communication. This equipment should meet the environmental conditions of use. Examples of instruments include (detailed information is described in AnnexA): Ionization chamber This is suitable for the measurement of air kerma and air absorbed dose and dose rate. In the environment, the correction due to temperature and atmospheric pressure may be required. NOTE2 For the measurement of ambient dose equivalent and dose equivalent rate the energy response may be compensated. Geiger-Muller (GM) counter The energy response should be corrected. GM counters may overestimate the readings due to the dose (rate) from cosmic radiation. Scintillation detector The energy response should be corrected. Detailed information is described in AnnexA and AnnexB. Semiconductor detector The energy response should be corrected.