Air　pollutant　distributions　identified　through　monitoring　form　an　important　basis　for　devising　adequate　emergency　responses　against　sudden　air　pollution　accidents　(SAPAs).　However,　studies　on　the　optimisation　of　monitoring　layouts　for　SAPAs,　which　can　help　us　better　understand　air　pollutant　dispersion,　are　lacking.　We　developed　an　emergency　monitoring　layout　optimisation　method　for　SAPAs　that　combines　an　air　pollutant　dispersion　model,　a　fuzzy　comprehensive　evaluation　method　(FCEM),　and　a　post-optimality　analysis　technique　(POAT)　to　identify　the　optimal　monitoring　layout　scheme　based　on　a　field　sulphur　hexafluoride　(SF6)　leakage　test.　The　impact　of　the　number　of　monitoring　sites　on　the　results　(coverage　rate　and　accuracy)　were　investigated　and　analysed　through　a　proposed　comprehensive　evaluation　method.　A　monitoring　result-monitoring　number　curve　was　plotted　to　determine　the　optimal　number　of　monitoring　sites.　Two　scenarios,　i.e.　with　and　without　environmentally　sensitive　monitoring　sites,　were　analysed.　The　results　showed　that　the　developed　optimisation　method　can　effectively　consider　the　role　of　sensitive　sites　and　obtain　a　feasible　network　for　monitoring　SAPAs.　The　coverage　rates　of　the　optimal　monitoring　layout　schemes　were　76.2%　and　61.9%　for　the　two　case　scenarios,　respectively;　the　relative　deviations　of　mean　air　pollutant　concentrations　at　the　sites　were　14.6%　and　-12.2%,　respectively.　We　investigated　the　effect　of　incorporating　POAT　into　the　method　by　comparing　the　optimal　emergency　monitoring　layout　schemes　based　on　dispersion　model-FCEM　and　model-FCEM-POAT.　The　results　showed　that　the　coverage　rates　of　the　optimised　monitoring　layout　schemes　improved　when　POAT　was　introduced.　The　proposed　method　can　help　determine　an　adequate,　optimised　emergency　monitoring　network　for　SAPAs.