Teams often down tools only to find haze still hanging in the air an hour later. That is not a faulty machine—it is physics and site dynamics. Knowing why dust lingers helps you plan effective run-times, placement, and housekeeping.

Small particles settle very slowly

Coarse debris drops fast, but PM10, PM2.5 and smaller can remain suspended for long periods. Minute thermal currents, people moving, and plant vibration keep particles aloft. Some dust stays airborne until it is filtered or it finds a surface.

Re-suspension keeps levels elevated

Every footstep, sweep, or blast of compressed air throws settled dust back up. Opening doors or starting ventilation can strip particles from surfaces and carry them through corridors into clean areas.

Controls that address the real behaviour

• Keep air scrubbers running 30–90 minutes after dusty work ends to purge residual airborne dust.
• Use negative pressure to pull clean air into the work zone and prevent outward leakage.
• Housekeeping with H-Class vacuums; avoid sweeping and compressed air.
• Bag and seal waste; cap ducts and tools before moving through clean spaces.
• Schedule dusty tasks when fewer people are present to reduce disturbance and exposure.

Verify when it is safe to stand down

• Track PM trends with a simple particulate monitor; aim for a sustained downward curve.
• Check visible haze and settled dust on test surfaces before removing barriers.
• If levels rebound when people re-enter, extend purge time or improve housekeeping.

Practical takeaways

• Fine dust can float for hours; plan post-task purge times.
• Prevent re-suspension with vacuuming, not sweeping.
• Use negative pressure to protect adjacent areas.
• Confirm with a PM meter rather than the eye alone.

Under COSHH, your duty is to reduce exposure as low as reasonably practicable. That means maintaining control after the tool is off—until the air is genuinely clear.