Verse 3 measuring an average of no more than 2.5 micron sized dust in accordance with article 2, is made in the general atmosphere and high from the ground of at least 1.5 metres but does not exceed 6 m.
3. Determination of average particle size less than 2.5 micron and 2 shall be made in a general and at least 1.5 meters above the ground, but no more than 6 meters.
The average 3 measurement of dust size not exceeding 2.5 micron. According to Article 2 to do the general atmosphere, and must be at least 1.5 meters high from the ground But no more than 6 meters.