The helium isotope composition of air might have changed since the industrial revolution due to the release of He-4-rich crustal helium during exploitation of fossil fuels. Thereby, variation of the atmospheric helium isotope ratio (He-3/He-4) has been proposed as a possible new atmospheric tracer of industrial activity. However, the magnitude of such change is debated, with possible values ranging from 0 to about 2 parts per thousand/yr (Sano et al., 1989; Hoffman and Nier, 1993; Pierson-Wickmann et al., 2001; Brennwald et al., 2013; Lupton and Evans, 2013). A new analytical facility for high precision (2 parts per thousand, 2 sigma) analysis of the He-3/He-4 ratio of air has been developed at CRPG Nancy (France) capable of investigating permil level variations. Previously, Brennwald et al. (2013) analyzed a selection of air samples archived since 1978 at Cape Grim, Tasmania, by the Commonwealth Scientific and Industrial Research Organisation (CSIRO). They reported a mean temporal decrease of the He-3/He-4 ratio of 0.23-0.30 parts per thousand/yr. Re-analysis of aliquots of the same samples using the new high-precision instrument showed no significant temporal decrease of the He-3/He-4 ratio (0.0095 +/- 0.033 parts per thousand/yr, 2 sigma) in the time interval 1978-2011. These new data constrain the mean He content of globally produced natural gas to about 0.034% or less, which is about 3x lower than commonly quoted. (c) 2015 Elsevier B.V. All rights reserved.