David Knight pulled out of the final round of the World Enduro Championship in Mendes, France on Sunday.
The four-times world champion said the dusty conditions made it too dangerous to continue.
'The dust was so bad in the special tests, especially in the Enduro test, that it was just too dangerous,' said the 33-year-old.
The KTM rider has only recently returned to racing after undergoing double hip-surgery.

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