Assess public-health risk
Separate a pollutant's hazard from the real-world risk it poses by combining how harmful it is with how much people are exposed.
- Exposure pathway basics: Risk depends on whether people are actually exposed, so the source-route-receptor idea must come first.
- Dose-response basics: Judging how harmful a pollutant is at a given amount relies on the dose-response idea.
Prerequisites are inferred: pending teacher review.
Re-learn the skill with worked practice and clear examples.
Risk combines hazard (how harmful a pollutant is) with exposure (how much people actually contact it). A high hazard with no exposure can be lower risk than a mild hazard everyone contacts.
A health team compares two pollutants in a town using the table. Pollutant X is far more harmful per unit but almost no one contacts it; Pollutant Y is mildly harmful but in the air everyone breathes all day. Which pollutant most likely poses the greater public-health risk, and why?
Reviewed| Pollutant | Hazard (harm potential) | Exposure (how much people contact it) |
|---|---|---|
| X | Very high | Almost none |
| Y | Low | Very high |
- A.X, because it is the more harmful pollutant
- B.Y, because risk combines hazard with how much people are actually exposed
- C.Neither, because only hazard matters for risk
- D.X, because exposure does not affect risk
Show the worked solution ▾
Answer: B. Y, because risk combines hazard with how much people are actually exposed
- Step 1: Read both factors: X: very high hazard but almost no exposure. Y: low hazard but very high exposure.
- Step 2: Combine them: Risk needs both hazard and exposure. X's harm rarely reaches anyone, while Y reaches everyone constantly, so Y likely poses the greater public-health risk.
Why it's right: Risk depends on hazard and exposure together; Y's widespread exposure can outweigh X's higher hazard that almost no one contacts.
- A: Harm potential alone is hazard, not risk; X's near-zero exposure keeps its risk low.
- C: Exposure matters too; risk is not hazard alone.
- D: Exposure strongly affects risk, so this reasoning is wrong.
Aligned to Environmental health: hazard vs. risk · reading level ~grade 10
- An agency ranks a widely-breathed mild air pollutant above a sealed toxic one when setting cleanup priorities.
Fill these in as you work through the lesson.
- Pollutant (a substance released into the environment):
- Hazard (the potential to cause harm):
- Risk (the real-world chance of harm):
- Exposure (the amount that actually reaches people):
A pollutant's is how harmful it could be; its is the real chance of harm, which depends on hazard combined with how much people actually have.
- A very harmful pollutant is locked away where no one contacts it. Is its hazard high, its risk high, or neither?
- Two pollutants are equally harmful, but people contact one far more. Which poses the greater risk?
- Why can a mild pollutant that everyone breathes daily pose more public-health risk than a deadly one nobody touches?
A town has two pollutants: Pollutant X is extremely toxic but sealed in a closed tank no one can reach; Pollutant Y is mildly toxic but is in the air everyone breathes all day. Decide which poses the greater public-health risk and justify your answer using hazard and exposure.