smartqhse-hse-calculators (Python)

30+ health, safety & environment (HSE) calculators — TRIR, LTIR, LTIFR, DART, EMR, severity rate, heat stress (WBGT), noise exposure, hand-arm vibration, ergonomics (REBA, RULA, NIOSH), fire load, evacuation time, manhours, risk matrix, incident cost, and more. Pure Python 3.11+, zero runtime dependencies, MIT licensed.

The Python port of @smartqhse/hse-calculators (TypeScript). Same formulas, same authoritative citations, Python-native API with type hints and dataclasses / TypedDicts.

🌐 Live calculators: tools.smartqhse.com 🏗️ Full HSE platform: smartqhse.com — AI-powered permits, risk assessments, incidents, audits, ISO 45001 compliance.

---

Installation

pip install smartqhse-hse-calculators

Zero runtime dependencies. Python 3.11+.

Quick start

from smartqhse_hse_calculators import (
    calculate_trir,
    calculate_ltifr,
    calculate_wbgt,
    calculate_risk_matrix,
)

# TRIR — OSHA Total Recordable Incident Rate
trir = calculate_trir(recordable_incidents=3, hours_worked=500_000)
print(trir.rate)   # 1.2
print(trir.base)   # 200_000

# LTIFR — ISO/ILO Lost Time Injury Frequency Rate
ltifr = calculate_ltifr(lost_time_injuries=3, hours_worked=500_000)
print(ltifr.rate)  # 6.0

# WBGT heat stress (ACGIH TLV / ISO 7243)
heat = calculate_wbgt(temp_c=38, humidity=60, globe_temp_c=42, indoor=False)
print(heat["risk_level"])            # 'high' or 'extreme'
print(heat["acgih_work_rest_ratio"]) # '25/75' or 'Stop work'

# 5×5 Risk matrix (oil & gas standard)
risk = calculate_risk_matrix(likelihood=4, severity=5, matrix="5x5")
print(risk["band"])     # 'extreme'
print(risk["action"])   # 'Intolerable — stop work, escalate to leadership'

---

Available calculators

Incident rate formulas

Function	Measures	Base	Regulation
calculate_trir	Total Recordable Incident Rate (OSHA)	200,000	29 CFR 1904.7
calculate_ltir	Lost Time Incident Rate (OSHA)	200,000	29 CFR 1904.7(b)(3)
calculate_ltifr	Lost Time Injury Frequency Rate (ISO/ILO)	1,000,000	ILO / ISO 45001:2018
calculate_dart	Days Away, Restricted, Transferred	200,000	29 CFR 1904.7(a)
calculate_severity_rate	Days lost per exposure base	200k / 1M	OSHA / ILO
calculate_frequency_rate	International accident frequency	1,000,000	HSE UK / IOGP
calculate_emr	Workers comp Experience Modification Rate	—	NCCI
calculate_incident_cost	OSHA $afety Pays direct + indirect	—	OSHA
calculate_heinrich_ratio	Near-miss pyramid ratios	—	Heinrich / Bird
calculate_safe_days	Days since last recordable	—	—
calculate_working_days_lost	ISO 45001 Clause 9.1 days-lost KPI	—	ISO 45001

Occupational exposure

Function	Measures	Regulation
calculate_noise_dose	Daily noise dose + 8-hr TWA	OSHA 29 CFR 1910.95
calculate_noise_exposure	Multi-segment TWA	OSHA / ACGIH
calculate_hav	Hand-Arm Vibration A(8)	HSE UK L140 / ISO 5349
calculate_wbv	Whole-Body Vibration A(8)	ISO 2631-1 / EU 2002/44/EC
calculate_coshh_risk_score	COSHH control banding	HSE UK COSHH Essentials

Environmental

Function	Measures	Regulation
calculate_wbgt	Wet Bulb Globe Temperature	ACGIH TLV / ISO 7243
calculate_heat_index	NWS heat index ("feels like")	NWS / OSHA
calculate_lux_level	Workplace illuminance	CIBSE / EN 12464-1
calculate_ventilation	Ventilation rate (ACH)	ASHRAE 62.1
calculate_carbon_footprint	Scope 1+2+3 CO₂e	GHG Protocol / ISO 14064-1

Ergonomics

Function	Measures	Source
calculate_niosh_lift	Recommended Weight Limit + Lifting Index	NIOSH 94-110
calculate_reba	Rapid Entire Body Assessment (1-15)	Hignett & McAtamney 2000
calculate_rula	Rapid Upper Limb Assessment (1-7)	McAtamney & Corlett 1993
calculate_manual_handling	HSE UK MAC risk banding	HSE UK MAC tool

Fire safety

Function	Measures	Source
calculate_fire_load	Fire load density (MJ/m²)	NFPA 557 / BS 9999
calculate_evacuation_time	RSET (Required Safe Egress Time)	NFPA 101 / BS 9999
calculate_fire_extinguisher_size	Min rating + count	NFPA 10 / BS 5306

Workload & risk

Function	Measures
calculate_manhours	Total exposure hours with overtime
calculate_fte	Full-time equivalent workers
calculate_risk_matrix	5×5 or 4×4 matrix scoring
calculate_risk_reduction	Pre/post residual reduction
calculate_safety_score	Composite 0-100 HSE KPI (A-F grade)
calculate_stress_risk	HSE UK Management Standards

---

Type safety

Every function has type hints. Result types are @dataclass(frozen=True) or TypedDict. Works with mypy --strict.

from smartqhse_hse_calculators.incident_rates import RateResult

result: RateResult = calculate_trir(recordable_incidents=3, hours_worked=500_000)
# result.rate  → float
# result.base  → int
# result.formula → str

---

Regulation citations

Every formula is rooted in a published regulation or peer-reviewed ergonomic standard. No proprietary calculations, no "SmartQHSE recommends" values.

United States

• 29 CFR 1904.7 — OSHA recordability (TRIR, LTIR, DART)
• 29 CFR 1910.95 — OSHA occupational noise
• NIOSH Publication 94-110 — Revised lifting equation
• NFPA 10, 101, 557 — Fire codes
• ASHRAE 62.1 — Ventilation
• NCCI — Workers comp EMR

United Kingdom

• HSE L140 — Hand-arm vibration
• HSE MAC tool — Manual handling
• BS 5306, BS 9999 — Fire safety
• HSE Stress Management Standards

International

• ISO 45001:2018 — OH&S management systems
• ISO 14064-1 — GHG quantification
• ISO 2631-1 — Whole-body vibration
• ISO 7243 — WBGT heat stress
• ILO — Frequency rate standards

Europe

• EU Directive 2003/10/EC — Noise
• EU Directive 2002/44/EC — Vibration
• EN 12464-1 — Workplace lighting

Professional bodies

• ACGIH TLVs® — Threshold Limit Values
• GHG Protocol — Scope 1/2/3 accounting
• IOGP — Oil & gas safety benchmarks
• NIOSH — National Institute for Occupational Safety and Health

---

Who uses this library

• Data scientists doing safety analytics in pandas / Jupyter
• Safety researchers running statistical analyses on HSE datasets
• Academic institutions teaching occupational health and safety
• Government agencies analysing workplace safety trends
• EHS software vendors embedding standardised calculations
• Consultants producing client reports with auditable formulas
• Industrial hygienists quantifying exposure

---

Full platform

SmartQHSE is the AI-powered HSE / QHSE management platform built on top of these calculators — permits, AI-generated risk assessments, incident management, contractor prequalification, ISO 45001 compliance dashboards.

---

License

MIT © SmartQHSE Ltd

Related

• TypeScript version: @smartqhse/hse-calculators
• Live web UI: tools.smartqhse.com
• HSE Benchmarks 2026 open dataset: smartqhse.com/datasets/hse-benchmarks-2026
• Awesome HSE: github.com/SmartQHSE/awesome-hse
• HSE knowledge base: smartqhse.com/answers