Calculator
Fill the fields below. The selector recommends a containment level and a practical control set.
Example data table
These examples are illustrative. Always align with your site rules, project specifications, and any applicable regulations.
| Scenario | Hazard | Work | Context | Suggested level |
|---|---|---|---|---|
| Small drilling in unoccupied storeroom | General Dust | Light | Low area, short duration, no HVAC return | Level 1 |
| Cutting concrete blocks inside an office | Silica | Moderate | Occupied, HVAC return present, 50 m² | Level 2 |
| Demolition of suspect materials near a clinic | Unknown / Mixed | Heavy | Sensitive adjacency, longer duration | Level 3 |
Run the calculator to see controls per level.
Formula used
The selector uses a transparent scoring model:
- Base score = (Hazard Points + Work Points) × Intensity Multiplier
- Context score adds area, duration, occupancy, sensitive adjacency, and HVAC return factors.
- Control score adjusts for wet methods, HEPA cleanup, negative pressure feasibility, ACH target, access points, and waste path control.
Finally, the total score maps to levels: 0–39 → Level 1, 40–69 → Level 2, 70+ → Level 3.
How to use this calculator
- Pick the hazard type and the work type that best match the task.
- Enter the area and duration to reflect the work scale.
- Set occupancy, sensitive adjacency, and HVAC to match site conditions.
- Choose available controls (wet methods, HEPA, negative pressure, ACH).
- Click Calculate, review the recommended level, and apply the listed controls.
- Use Download CSV or Download PDF to attach the result to a method statement.
If hazards are uncertain, assume higher risk and consult specialists.
Professional guidance article
1) Why containment levels matter on active sites
Dust and fibers migrate fast in real buildings. A single HVAC return can distribute fine particles well beyond the work face. This selector treats occupancy and air movement as major drivers, adding up to 42 points from occupancy (14), sensitive adjacency (16), and return air (12) when present.
2) Risk scoring inputs and how they scale
Hazard points range from 10 for general dust to 40 for unknown or mixed hazards. Work points range from 10 for light drilling to 30 for heavy demolition. Intensity then applies a multiplier of 0.85 (low), 1.00 (medium), or 1.20 (high) to reflect dust generation rate.
3) Area and duration bands used in the calculator
Larger scopes are harder to seal and keep clean. The model adds 2–22 points for area, with key breaks at 10, 50, 200, and 1000 m². Duration adds 2–18 points, stepping at 1, 3, 7, and 21 days. These bands help standardize planning across multiple crews and zones.
4) Control measures that reduce the score
Controls are treated as measurable reductions. Wet methods can reduce the score by 6, HEPA cleanup by 8, and feasible negative pressure by 10. Ventilation targets also matter: below 4 ACH adds risk, while 6–12 ACH typically reduces the score. A controlled waste path can reduce tracking by 6.
5) Interpreting Level 1, 2, and 3 results
The score maps to containment levels: 0–39 suggests Level 1, 40–69 suggests Level 2, and 70+ suggests Level 3. Use Level 1 for small, short tasks with limited exposure routes. Level 2 is appropriate for occupied buildings or silica cutting with engineered controls. Level 3 is recommended for high-hazard or high-uncertainty work, where full containment and verification are needed.
FAQs
1) Is this tool a replacement for site regulations?
No. Use it for structured planning and documentation. Always comply with your contract requirements, safety plan, and any applicable regulations or specialist guidance for regulated hazards.
2) What does the score represent?
The score is a relative risk index based on hazard severity, work intensity, exposure context, and available controls. Higher scores indicate a need for stronger isolation and verification.
3) Why does occupancy increase the recommended level?
Occupied spaces increase exposure likelihood and sensitivity to dust. The model adds points for occupancy to encourage better separation, cleanup discipline, and communication.
4) How should I choose the hazard type?
Select the most credible hazard based on surveys, drawings, and materials. If uncertain, choose “Unknown / Mixed Hazards” and seek sampling or specialist review.
5) What ACH value should I enter?
Enter your planned air scrubber/ventilation target. If unknown, use 0. Values under 4 ACH add risk; 6–12 ACH typically supports Level 2–3 containment performance.
6) Why do access points matter?
Each opening is a potential leak path. More access points increase the likelihood of pressure loss, barrier damage, and tracking contamination.
7) When should I escalate to Level 3?
Escalate when hazards are highly toxic or uncertain, sensitive areas are nearby, or you cannot reliably control airflow and waste movement. Level 3 supports full containment and verification.