DESNZ and OPRED have updated the PON1 guidance to provide additional information relating to excessive venting of bulk powders (Appendix J).
A PON1 must be submitted where there has been an excessive vent of bulk powders – OPRED expects measures are implemented to prevent excessive vents. These may include constant monitoring of vents during bunkering, robust procedures in place and an awareness of what a normal vent looks like (photographs/video) which can be used to compare against any perceived excessive vent.
Source: DESNZ, OPRED.