Calculadora de Smog/Benzopireno
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
Exposição = concentração × volume_resp; risco = exposição × anos × fator_risco_unitário
About this calculator
The Smog/Benzo[a]pyrene Calculator estimates daily exposure to benzo[a]pyrene, a polycyclic aromatic hydrocarbon found in air pollution, and calculates the lifetime cancer risk. Benzo[a]pyrene is formed during incomplete combustion of fossil fuels such as coal, diesel, and gasoline, as well as cigarette smoke and wildfires. The tool uses the pollutant concentration in air (in ng/m³) and the average daily breathing volume (in m³) to compute daily exposure. It then multiplies this by the exposure duration in years and a unit risk factor, which represents the cancer probability per unit of cumulative exposure.
How it works: the user inputs the average benzo[a]pyrene concentration in their area, which can be obtained from air quality monitoring stations or environmental reports. The standard breathing volume is 20 m³/day for adults, but can be adjusted for children (lower) or exposed workers (higher). The unit risk factor is based on guidelines from the World Health Organization (WHO) and the US Environmental Protection Agency (EPA), set at 8.7 × 10⁻⁵ (per ng/m³ per year). The result is the additional lifetime cancer risk, expressed as a probability (e.g., 1 in 100,000).
When to use? Ideal for residents of large urban centers with high pollution, public health professionals, ecology students, and citizens concerned about pollution effects. The calculator helps quantify the impact of chronic exposure to benzo[a]pyrene, classified as a Group 1 carcinogen by the IARC. It is also useful for comparing scenarios: for example, living near a busy road versus a rural area, or before and after pollution control measures.
Important precautions: Benzo[a]pyrene concentration varies greatly with location, climate, and emission sources. Accurate data is essential; using annual average values is more reliable than spot measurements. The model assumes continuous and constant exposure, which may not reflect seasonal peaks. Additionally, the unit risk factor is a population estimate, not an individual one. Genetic factors, habits (smoking), and other exposures can alter the actual risk. This calculator does not replace medical or occupational risk assessment.
Frequently asked questions
What does 'lifetime cancer risk' mean?
It is the additional probability of developing cancer due to benzo[a]pyrene exposure compared to an unexposed person. For example, 1 in 100,000 means that in a group of 100,000 exposed people, one may develop cancer from this cause.
Where can I find benzo[a]pyrene concentration in my city?
Check air quality reports from local environmental agencies, such as the EPA or state monitoring networks. Concentration is usually measured in ng/m³.
Does the calculator apply to secondhand smoke?
Yes, but cigarette smoke contains much higher levels. The calculator only considers ambient exposure. Smokers have a much higher additional risk.
Can I use it for occupational exposure (factory work)?
Yes, if you input the workplace concentration and adjust breathing volume for physical activity. Refer to safety standards for reliable data.
What is the difference between unit risk and calculated risk?
The unit risk (8.7e-5) is the risk per ng/m³ per year of exposure. The calculated risk is the product of concentration and years, giving the total risk.