Guideline VDI 4219 specifies methods for determining the uncertainty of emission measurements by use of discontinuous measurement methods. The guideline describes two equivalent approaches: - a direct approach based on paired measurements using the overall measurement method; - an indirect approach with individual assessment of all sub-steps (input quantities) of the validated measurement method that contribute to the measurement uncertainty Guideline VDI 4219 implements the general recommendations of the Guide to the Expression of Uncertainty in Measurement (Leitfaden zur Angabe der Unsicherheit beim Messen) (DIN V ENV 13005) and the specific requirements of DIN EN ISO 20988 on the determination of measurement uncertainty for emission measurements by use of discontinuous measurement methods. The measurement uncertainty determined in accordance with this guideline can be used, for example, to assess the results of individual measurements according to TA Luft. The procedure for determining measurement uncertainty as described in this guideline applies to the use of standard reference methods or other validated measurement methods within the range of validity to be defined by the user.