But Why: A Podcast for Curious Kids

Episode Title: How does wildfire smoke travel so far?
Host: Jane Lindholm, Vermont Public
Air Date: August 29, 2025

Episode Overview

This bonus episode explores an increasingly common atmospheric phenomenon: wildfire smoke traveling far from its source. Host Jane Lindholm and her expert guests answer kid-submitted questions about why wildfire smoke can reach distant places, why there’s more smoke lately, how it affects our health, and what we can do to stay safe. The episode features atmospheric scientist Professor Joel Thornton and primary care physician Dr. Greg Furey.

Key Discussion Points & Insights

1. What is Wildfire Smoke and Why Do We See It?

Timestamps: 02:55 – 03:22

• Professor Joel Thornton explains that wildfires inject tiny particles into the air, which block sunlight and create hazy, smoky skies.
  • “When forests are on fire, it's injecting a lot of little tiny particles into the air, and those then can travel great distances and cover large parts of the landscape.” (02:55, Joel Thornton)
  • These particles, smaller than grains of sand, are mostly made of burned material—“carbonitious materials,” like trees and leaves.

2. How Far (and Fast) Can Smoke Travel?

Timestamps: 03:50 – 05:23

• Professor Thornton describes how quickly air moves around the planet:
  • “If I could hold on to a little bit of packet of air for a minute and I let it go, that packet could go around the earth in about two weeks.” (03:50, Joel Thornton)
• The smoke from wildfires can rise high into the atmosphere, as much as five miles, and get caught in the jet stream—fast-moving currents of air that circulate the globe.
  • “Fires in Canada…within just a few days can be from the western part of Canada all the way into the eastern part of the United States.” (03:50, Joel Thornton)
• Wildfire smoke travels much farther than smoke from a campfire, mainly because the heat from wildfires can loft it into these fast-moving air currents.

3. Why Are There So Many Wildfires and Smoke Now?

Timestamps: 05:32 – 07:43

• Wildfires are burning more areas because of a combination of factors:
  • Earth’s warming climate causes forests to dry out more quickly, making them prone to burning.
    • “Warmer air basically causes trees in the ground to dry out faster. So when it's warmer, the air just sort of sucks up the water from these things.” (05:42, Joel Thornton)
  • Natural factors like lightning, weather patterns, and also human land use and fire management practices play roles.
  • “We've…really changed our relationship with forests and with land over time, going back to when we started clearing forests to make room for farms and agriculture. That's been going on for really thousands of years.” (06:48, Joel Thornton)

4. Why Does Wildfire Smoke Smell Different from Firewood?

Timestamps: 07:53 – 08:35

• The science of smell is complex: Even tiny differences in molecules can create big differences in smell.
• Wildfires burn many things (not just dry wood), including leaves, dirt, and living branches, producing a much harsher smell.
  • “Firewood that you're using to sit in your fireplace at home, maybe a specific type of wood, it's probably very dry. Whereas wildfires, there's lots of things burning, things like the dirt is literally burning in a wildfire…” (07:53, Joel Thornton)
• Both kinds of smoke are unhealthy to breathe.

5. Health Effects of Wildfire Smoke

Timestamps: 09:00 – 11:01

• Dr. Greg Furey explains that smoke contains “particulate matter pollution”—extremely small particles that get into our lungs and even the rest of our bodies.
  • “Those really, really, really small particles can get into the body and then can go on to affect essentially any part of the body.” (09:46, Dr. Greg Furey)
• Even a simple cough can be the body’s reaction to inflammation caused by these fine particles.
  • “The main reason people cough when they're exposed to smoke is because these fine particles…cause inflammation in the lungs.” (10:20, Dr. Greg Furey)
• Some people are more vulnerable: those with lung conditions like asthma, the elderly, children, and pregnant women.

6. How to Stay Safe and Healthy During Wildfire Smoke Events

Timestamps: 11:01 – 12:28

• Visual signs (hazy skies, odd sun color) and the official Air Quality Index (AQI) can let you know when air is unsafe.
  • AQI scale: 0 (clean) to 500 (very polluted). Above 100: sensitive groups should take precautions. Above 300: everyone should.
    • “Once the AQI or the Air Quality index goes above 100 but is less than 300 people who are in some of the more sensitive groups…should be starting to think about how they're going to take precautions…” (12:07, Dr. Greg Furey)
• Steps to take include staying inside, slowing down on outdoor activities, using masks or air filters, and consulting a doctor if you’re in a sensitive group.
• Making a habit of checking the AQI with an adult during wildfire season is encouraged.

Notable Quotes & Memorable Moments

• “If I could hold on to a little bit of packet of air for a minute and I let it go, that packet could go around the earth in about two weeks.”
  — Joel Thornton (03:50)
• “Warmer air basically causes trees and the ground to dry out faster… So then what starts those fires can be natural… or management practices.”
  — Joel Thornton (05:42)
• “Those really, really, really small particles can get into the body and then can go on to affect essentially any part of the body.”
  — Dr. Greg Furey (09:46)
• “The main reason people cough when they're exposed to smoke is because these fine particles…cause inflammation in the lungs.”
  — Dr. Greg Furey (10:20)

Important Timestamps

• 02:55 — What wildfire smoke is, and why the sky gets hazy
• 03:50 — How fast and far wildfire smoke can travel
• 05:42 — Why wildfires and smoky days are becoming more common
• 07:53 — Why smoke smells bad, and why wildfire smoke smells worse
• 09:11 — Health effects of breathing in wildfire smoke
• 10:20 — Why smoke makes you cough
• 12:07 — Understanding the Air Quality Index (AQI) and who should be careful

Conclusion

This episode provides clear, science-based answers to kids' real-world questions about wildfire smoke. With engaging expert explanations and practical advice on staying safe during smoky days, it helps kids and families understand both the “why” and the “what now” of wildfire smoke in our changing world.

For more curious questions and answers, submit your own to But Why: questions@butwhykids.org.