A photoionization detector (100) comprises an ultraviolet radiation source (130); one or more detector electrodes (204 and 205); and a shielding material (206) located between the ultraviolet radiation source (130) and the one or more detector electrodes (204 and 205), wherein the ultraviolet radiation (240) does not directly impinge on any part of the one or more detector electrodes (204 and 205). A method for gas detection comprises exposing a photoionization detector (100) to an environment containing a target gas; and shielding the one or more detector electrodes (204 and 205) from direct impingement from the ultraviolet radiation (240) via the shielding material (206).