Part 4: Smoke Chemistry Lecture

Complete the notes below.
Write ONE WORD ONLY for each answer.

Wildfire smoke and indoor exposure

Outdoor chemistry

• Smoke plumes can produce [31] ____________________ pollutants as they age.
• One key driver of these reactions is strong [32] ____________________.

Health and particles

• Fine particles can reach the [33] ____________________ of the lungs.
• Some compounds in smoke irritate the eyes and [34] ____________________.

Keeping indoor air cleaner

• Smoke enters homes through cracks and through [35] ____________________ systems.
• The simplest action is to create one clean room with a portable [36] ____________________.
• If using a fan-and-filter setup, the filter should fit with minimal [37] ____________________.

Measuring and guidance

• Low-cost monitors can be useful but need regular [38] ____________________ checks.
• Official alerts often refer to PM [39] ____________________.
• Long-term protection improves when buildings have better [40] ____________________ control.

Keys

Transcripts

Part 4: You will hear a lecture about wildfire smoke chemistry and how to reduce indoor exposure.

Today I want to explain wildfire smoke chemistry and why indoor exposure can remain high even when you stay inside. People often think smoke is simply ash and soot, but in reality a smoke plume behaves like a moving chemical reactor, changing as it travels.

Let’s start with outdoor chemistry. When smoke leaves the fire, it contains particles and a mix of gases. As the plume ages, it can produce secondary pollutants. These are not always emitted directly; they are formed through reactions in the air. A key driver of these reactions is strong sunlight. Sunlight provides energy that speeds up oxidation and helps create new compounds, some of which then condense onto existing particles.

Now, health and particles. The size of the particles matters more than many people realise. Fine particles can reach the alveoli of the lungs, the deepest region where gas exchange occurs. Once there, they can trigger inflammation. Smoke also contains compounds that irritate the eyes and the throat, which is why people often report burning sensations, coughing, or a sore throat even when the pollution level seems only moderate on a general air-quality map.

So how do we keep indoor air cleaner? Closing windows helps, but it is not a complete solution. Outdoor air enters through cracks, and it also enters through ventilation systems, including bathroom fans, kitchen extractors, and building intake vents. In many homes the best short-term strategy is to create one clean room. Choose a room you can close off, ideally with fewer windows, and use a portable air purifier. Place it so it can circulate air freely, and keep the door closed as much as possible. If resources are limited, prioritise sleeping areas, because exposure overnight is long and uninterrupted.

You may have seen DIY fan-and-filter setups. These can be effective, but only if the filter fits tightly with minimal leakage. If air bypasses the filter around the edges, you will move a lot of air but remove far fewer fine particles. Use tape or a simple frame so the seal is close. Also try to avoid creating extra indoor particles during smoke events. Frying food is a common source, as are candles and vacuuming with a poor filter. Even sweeping can resuspend dust, so choose gentler cleaning methods until the air improves. If you do need to cook, use a lid and keep heat lower where possible.

This approach also scales to shared buildings. In schools and workplaces, a clean-room plan can protect more vulnerable people without trying to treat an entire building at once. Another useful habit is to reduce door opening, because repeated door swings let smoky air rush in; group errands and keep trips outside brief.

Finally, measuring and guidance. Low-cost monitors are widely sold and they can help you understand conditions in your own neighbourhood, but they need regular accuracy checks. Sensors can drift with time, humidity, and dust loading. If you use them, compare occasionally with a reference station or follow the manufacturer guidance for calibration. Public alerts often refer to PM2.5 because this size fraction is strongly linked to health outcomes and penetrates deeply into the lungs. However, PM2.5 is not the only hazard, since ozone and other gases can rise too, and those are not captured by every home sensor. That is why official advice combines multiple indicators rather than relying on a single number. A practical tip is to watch the trend over time, because one spike might reflect an indoor activity rather than outdoor smoke.

Long-term protection depends on buildings. The most effective approach is better sealing. That means controlling how much outdoor air enters, filtering it, and avoiding uncontrolled leakage. Improving seals around doors and windows, maintaining filters in HVAC systems, and designing for clean-air rooms in public buildings all reduce exposure. It is not only a personal responsibility issue; it is also a design and policy issue. When you combine better building control with clear public messaging, you reduce exposure for the whole population, including people who cannot afford specialised equipment.