Accordingly, Carbon Dioxide is classified as a Class 2 substance, a substance which has an obvious effect on a horse.  The internationally agreed threshold / concentration applied by the NHA for Carbon Dioxide is 36 millimoles available Carbon Dioxide per litre in plasma.
 
Cobalt is classified as a Class 3 substance, a substance which has the potential to affect the performance of the horse.  The internationally agreed threshold / concentration applied by the NHA for Cobalt is 0.1 microgram total cobalt per millilitre in urine.