Marine fuelh are covered by an ISO specification and there are controls on various Parameters. The standard also specifies that fuel shall not contain any added substance or chemical waste which jeopardises the safety of ships or adversely affects the performance of machinery or is harmful to personnel or contributes overall to air pollution. Although the limited routine bunker acceptance tests do not make a detailed chemical analysis, one specialist analysis company has reported that 2% or 3% of fuels analysed have evidence of chemical waste.