  We use Swift blazar spectra to estimate the key intergalactic medium (IGM)
properties of hydrogen column density(Nhxigm), metallicity and temperature over
a redshift range of 0.03 leq z leq 4.7, using a collisional ionisation
equilibrium(CIE) model for the ionised plasma. We adopted a conservative
approach to the blazar continuum model given its intrinsic variability and use
a range of power law models. We subjected our results to a number of tests and
found that the Nhxigm parameter was robust with respect to individual exposure
data and co-added spectra for each source, and between Swift and XMM-Newton
source data. We also found no relation between Nhxigm and variations in source
flux or intrinsic power laws. Though some objects may have a bulk
Comptonisation component which could mimic absorption, it did not alter our
overall results. The Nhxigm from the combined blazar sample scales
as(1+z)^1.8+\-0.2. The mean hydrogen density at z = 0 is n0 = (3.2+\-0.5) x
10^-7 cm^-3. The mean IGM temperature over the full redshift range is log(T\K)
= 6.1+\-0.1 and the mean metallicity is [X\H] = -1.62+\-0.04 (Z sim0.02) When
combining with the results with a gamma-ray burst (GRB) sample, we find the
results are consistent over an extended redshift range of 0.03 leq z leq 6.3.
Using our model for blazars and GRBs, we conclude that the IGM contributes
substantially to the total absorption seen in both blazar and GRB spectra.
