If the level of dust measured in the air in application of article R. 1334-27 is less than or equal to the value of five fibres per litre, the owner shall have the periodic assessment of the state of conservation of list A materials and products containing asbestos provided for in article R. 1334-20 carried out, within a maximum period of three years from the date of submission of the results of the dust measurements or on the occasion of any substantial change to the structure or its use.
If the level of dust measured in the air pursuant to article R. 1334-27 is greater than five fibres per litre, the owner must have asbestos containment or removal work carried out in accordance with the procedures laid down in article R. 1334-29.