Chalk dust is usually calcium carbonate (or gypsum) and is classed as low toxicity. Even so, the fine fraction can irritate airways and trigger asthma. In schools and training rooms, and in maintenance tasks where boards are cut or cleaned, simple controls protect comfort and health while keeping rooms usable.

What chalk dust is and why it matters

• Particles are mostly larger (PM10), but a respirable fraction exists and can linger in poorly ventilated spaces.
• It is not silica dust, but it can worsen asthma and dry throat, especially with frequent exposure.
• Markers and cleaners can add VOCs; odour is a clue to poor air quality, not just dust.

Practical controls for classrooms and training spaces

• Use low-dust chalk or dampen sticks lightly to cut shedding.
• Clean boards with a slightly damp microfibre cloth; avoid dry erasers that re-suspend dust.
• Ventilate between sessions. Cross-ventilate where safe, or run a portable air cleaner with high-efficiency filtration (H13/H14) during and after lessons.
• Housekeeping: vacuum floors and ledges with a HEPA-equipped machine, not a broom. Empty bags and filters outdoors.
• Store chalk in closed containers and replace crumbly sticks.

Maintenance and site teams

• When drilling or cutting near boards, treat it as construction dust control: tool extraction (M/H-class), and wet methods where practical.
• Use RPE for dustier tasks (FFP2 or FFP3 depending on risk) and ensure face-fit testing.
• If dust persists in older rooms, consider a portable air scrubber; units from providers like MAXVAC are commonly used in education maintenance programmes.

Compliance context

Under HSE EH40, the general WEL for inhalable dust is 10 mg/m³ and 4 mg/m³ for respirable dust. Schools and offices should aim well below these by managing sources, ventilation and cleaning.

Practical takeaways

• Reduce shedding at source, clean with damp microfibre, and avoid sweeping.
• Ventilate or use HEPA air cleaning in rooms with persistent dust build-up.
• Apply construction-grade controls for maintenance tasks that generate visible dust.
• Provide RPE and face-fit where tasks temporarily raise exposure.

With modest changes to cleaning, ventilation and task planning, chalk dust becomes a manageable nuisance rather than a health or comfort issue.