# Air Monitoring and Gas Detection Quiz

Free practice quiz · 10 questions

Answer every question, then press **Check my answers** to see your score and an explanation for each one. Study first with the guide: [HAZWOPER Air Monitoring: Oxygen, LEL, Toxics and Direct-Reading Instruments](https://www.hazwoperosha.com/guides/air-monitoring/).

**1. Above what oxygen level is an atmosphere considered oxygen enriched?**

- 20.9%
- 21.5%
- 23.5%
- 30%

**Answer: 23.5%.** Above 23.5% oxygen is enriched and increases fire risk.

**2. What should you test first on initial entry?**

- Toxic gases
- Oxygen
- Radiation
- Noise

**Answer: Oxygen.** Test oxygen first: low oxygen kills quickly and also affects combustible gas readings.

**3. What does LEL stand for?**

- Lowest exposure limit
- Lower explosive limit
- Legal exposure level
- Lethal environment level

**Answer: Lower explosive limit.** The lower explosive limit is the lowest concentration of a gas in air that will ignite.

**4. Which instrument does NOT respond well to methane?**

- FID
- CGI/LEL sensor
- PID
- Methane-specific IR sensor

**Answer: PID.** Methane's ionization potential is higher than standard PID lamp energies, so PIDs miss it. FIDs detect it.

**5. A typical 4-gas meter measures:**

- O2, LEL, H2S and CO
- O2, CO2, N2 and Ar
- Benzene, toluene, xylene and ethylbenzene
- Radon, ozone, NO2 and SO2

**Answer: O2, LEL, H2S and CO.** Standard 4-gas meters measure oxygen, combustibles (LEL), hydrogen sulfide and carbon monoxide.

**6. What is a bump test?**

- Dropping the meter to test durability
- Exposing the meter to a known gas to check the sensors and alarms respond
- Replacing sensors
- Charging the battery

**Answer: Exposing the meter to a known gas to check the sensors and alarms respond.** A bump test is a functional check, usually done before each day's use.

**7. Gases with a vapor density greater than 1 tend to:**

- Rise
- Sink and collect in low areas
- Disperse evenly
- Disappear

**Answer: Sink and collect in low areas.** Heavier-than-air gases sink into trenches, pits and basements, so monitor low points.

**8. Which gives a reading for one specific chemical?**

- PID
- FID
- Colorimetric detector tube
- LEL sensor

**Answer: Colorimetric detector tube.** Colorimetric tubes are chemical-specific; PIDs and FIDs respond to many compounds.

**9. A STEL is averaged over:**

- 15 minutes
- 1 hour
- 8 hours
- 40 hours

**Answer: 15 minutes.** A short-term exposure limit is a 15-minute time-weighted average.

**10. Combustible gas readings are accurate only when:**

- It is raining
- Oxygen levels are normal
- The meter is new
- The reading is above 50% LEL

**Answer: Oxygen levels are normal.** Catalytic LEL sensors need oxygen; in oxygen-deficient air they can read low.

## More free HAZWOPER quizzes

- [HAZWOPER 40 Hour Practice Test](https://www.hazwoperosha.com/quizzes/hazwoper-40-hour-practice-test/) · Free quiz · 15 questions - Free HAZWOPER 40 hour practice test with answers and explanations. 15 questions on OSHA 1910.120 training levels, PPE,...
- [HAZWOPER 8 Hour Refresher Practice Quiz](https://www.hazwoperosha.com/quizzes/hazwoper-8-hour-refresher-practice-quiz/) · Free quiz · 10 questions - Free HAZWOPER 8 hour refresher practice quiz with answers. Review refresher deadlines, medical surveillance, the HASP,...
- [HAZWOPER PPE Levels Quiz (Levels A, B, C and D)](https://www.hazwoperosha.com/quizzes/ppe-levels-quiz/) · Free quiz · 10 questions - Free quiz on HAZWOPER PPE levels A, B, C and D with answers. Test what each level includes, when to use it, respirator...
- [Decontamination and Site Control Quiz](https://www.hazwoperosha.com/quizzes/decontamination-and-site-control-quiz/) · Free quiz · 10 questions - Free HAZWOPER decontamination and site control quiz with answers: work zones, decon line order, access control points,...
- [HAZWOPER First Responder Awareness Level Quiz](https://www.hazwoperosha.com/quizzes/first-responder-awareness-quiz/) · Free quiz · 10 questions - Free HAZWOPER first responder awareness level quiz with answers: (q)(6) responder levels, the DOT Emergency Response...
- [RCRA Hazardous Waste Generator Quiz](https://www.hazwoperosha.com/quizzes/rcra-hazardous-waste-quiz/) · Free quiz · 10 questions - Free RCRA hazardous waste quiz with answers: generator categories, accumulation limits, satellite accumulation,...

---

Page: https://www.hazwoperosha.com/quizzes/air-monitoring-quiz/
HazwoperOSHA.com: [Home](https://www.hazwoperosha.com/) · [Courses](https://www.hazwoperosha.com/#courses) · [About](https://www.hazwoperosha.com/about/) · [Contact](https://www.hazwoperosha.com/contact/) · [Privacy](https://www.hazwoperosha.com/privacy/) · [llms.txt](https://www.hazwoperosha.com/llms.txt) · [Sitemap](https://www.hazwoperosha.com/sitemap.xml)
Questions: +1-866-429-6742 · sales@hazwoper-osha.com