Benzo[a]Pyrene Cancer Risk Calculator
Estimate the excess lifetime cancer risk from breathing air contaminated with benzo[a]pyrene — a Group 1 human carcinogen produced by incomplete combustion. Enter concentration, exposure duration and frequency.
ng/m³
years
days/year
Moderate (1–10 in 100,000)
- 1
Exposure time fraction
(350 ÷ 365) × (30 ÷ 70) = 0.41096Scales the continuous-lifetime unit risk to your actual exposure pattern. - 2
Concentration × unit risk
1 × 8.7×10⁻⁵ = 0.000087 - 3
ILCR (probability)
0.000087 × 0.41096 = 0.000035753 - 4
Risk per million
0.000035753 × 1 000 000 = 35.753
How does this calculator work?
B[a]P inhalation risk = concentration (ng/m³) × 8.7×10⁻⁵ × (days exposed/365) × (years exposed/70). The WHO guideline of 0.12 ng/m³ corresponds to 10⁻⁵ excess lifetime cancer risk. Risks above 10⁻⁴ typically trigger regulatory concern. Source: WHO Air Quality Guidelines Europe, 2000.
Formula
How this is calculated
Benzo[a]pyrene (B[a]P) is the reference compound for carcinogenic polycyclic aromatic hydrocarbons (PAHs). It is produced by incomplete combustion of organic matter — vehicle exhausts, wood burning, barbecuing and industrial sources all emit it. The WHO inhalation unit risk (IUR) of 8.7 × 10⁻⁵ per ng/m³ represents the excess lifetime cancer risk per unit of air concentration for continuous exposure over a 70-year reference lifetime. This is the value behind the WHO Air Quality Guideline (Europe, 2000) annual-average limit of 0.12 ng/m³, which corresponds to approximately 10⁻⁵ (one extra cancer case per 100,000 people) for lifelong continuous exposure.
For real exposure scenarios, the unit risk is scaled down by two factors: the fraction of the year during which the person breathes that air (EF/365) and the fraction of a 70-year lifetime over which the exposure occurs (ED/70). Multiplying C × IUR × (EF/365) × (ED/70) gives the Inhalation Excess Lifetime Cancer Risk (ILCR).
Important limitations: the IUR was derived from epidemiological studies of occupationally exposed workers and extrapolated to the general population. It covers inhalation only — oral ingestion via contaminated soil or food requires the EPA oral slope factor (7.3 (mg/kg-day)⁻¹) in a separate intake model. Real air also contains other PAHs, which are commonly assessed by converting their masses to B[a]P-equivalent concentrations using toxic equivalency factors (TEFs). Values used here are 2026 estimates and are editable defaults.
Frequently asked questions
The WHO Air Quality Guideline (Europe, 2000) annual average is 0.12 ng/m³, corresponding to a 10⁻⁵ excess lifetime cancer risk for continuous 70-year exposure. Urban monitoring stations commonly record 0.1–2 ng/m³; near industrial point sources levels can be 10–100× higher.
Regulatory agencies typically treat 10⁻⁶ (one in a million) as the de minimis (acceptable) risk and 10⁻⁴ (one in ten thousand) as the level that triggers action. The WHO guideline of 10⁻⁵ sits between those thresholds. Country-specific standards vary — always consult the relevant national regulator.
No. It covers inhalation of B[a]P only. Other carcinogenic PAHs (benz[a]anthracene, chrysene, etc.) can be converted to B[a]P equivalents using their toxic equivalency factors (TEFs) and then added. Dermal and oral routes use EPA IRIS oral slope factor and separate intake models.
Also known as
TG we-Calculate Editorial Team. (2026). Benzo[a]Pyrene Cancer Risk Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/benzoapyrene-calculator
TG we-Calculate Editorial Team. "Benzo[a]Pyrene Cancer Risk Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/benzoapyrene-calculator.
TG we-Calculate Editorial Team, "Benzo[a]Pyrene Cancer Risk Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/benzoapyrene-calculator
@misc{wecalculate_benzoapyrene_calculator, title = {Benzo[a]Pyrene Cancer Risk Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/benzoapyrene-calculator}}, year = {2026}, note = {TG we-Calculate} }
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