This International Standard specifies safety requirements and their verification for the design and construction of knapsack mistblowers incorporating a combustion engine where the air flow is generated by a fan. It describes methods for the elimination or reduction of hazards arising from their use. In addition, it specifies the type of information on safe working practices to be provided by the manufacturer. It does not, however, give any technical requirement for reducing noise or vibration hazards. Indeed, the different means available to reduce these hazards are a matter for the technical aids to which the manufacturer may resort, through specialized books or specified bodies. This International Standard deals with all significant hazards, hazardous situations and events, excepting those arising from - electromagnetic compatibility, - static electricity, - explosion or fire from chemicals for spraying, - insufficient structural integrity, and - noise and vibration.It is applicable to knapsack combustion-engine-driven mistblowers when they are used as intended and under the conditions foreseen by the manufacturer (see Clause 4). It is not applicable to knapsack combustion-engine-driven mistblowers manufactured before the date of its publication.