Why Better Indoor Air Might Come on Four Legs (and Why CO₂ Alone Doesn’t Cut It)
Why Your Dog Might Be a Better Air Quality Indicator Than Your CO₂ Monitor
Most of us consider home air quality in simple terms: if it smells fine and feels comfortable, it’s probably good, right? However, there's much more to it. Dr. Stephanie Taylor, a former physician and current building science expert, joined us to explain why indoor air quality (IAQ) is about health, not just comfort. She shared insights that were quite eye-opening, especially when she suggested that your dog could be part of your air quality strategy.
Let’s break it down for those unfamiliar with HVAC or microbiology.
Humans: Tiny Particle Machines
Believe it or not, just by being in a room, each person releases around 37 million microscopic particles every hour. These particles come from your skin, clothes, breath, and more, carrying your unique mix of bacteria and microbes. They don’t just float in the air; they settle on surfaces, become airborne again when disturbed, and change based on the temperature, moisture, and ventilation in the space.
Your home, office, or school isn’t a sealed box; it’s a living system reflecting the people (and pets) inside. Instead of trying to make it sterile like a hospital, we need to design for a healthy balance of beneficial microbes. This involves managing airflow, materials, and moisture thoughtfully.
Humidity: Not Just About Dry Skin
When we discuss relative humidity (RH), we’re referring to the moisture content in the air. If indoor humidity drops too low—especially below 40%—your body’s natural defenses are compromised. Your nose dries out, mucus thickens, and your ability to fight off germs decreases. This is why winter air often feels harsher, and why people get sick more easily in dry environments.
Dr. Taylor’s advice was straightforward: maintain indoor humidity between 40 and 60 percent if possible. In colder climates, it may need to dip slightly lower to prevent moisture buildup inside walls, but it should remain above 35%. She shared a story about someone who left their well-humidified home and spent a few nights in a very dry rental, returning with the worst flu they’d had in years.
So yes, managing indoor moisture protects your walls, but it also safeguards your lungs.
CO₂ Isn’t the Whole Story
Carbon dioxide (CO₂) is often used as a quick way to assess whether there’s enough fresh air in a room. When CO₂ levels rise, it usually indicates the space is crowded or under-ventilated. However, Dr. Taylor pointed out that this only tells part of the story.
In places like submarines, people can adapt to very high CO₂ levels without noticeable issues because they are in carefully managed environments. For the rest of us, indoor air quality isn’t just about one number; it’s about the full mix of elements in the air.
Let’s break that mix down:
CO₂ – Indicates how stale the air is and how many people have been breathing in the space.
PM (Particulate Matter) – Tiny particles in the air from dust, smoke, cooking, or even candles. The smaller they are, the deeper they can penetrate your lungs.
VOC (Volatile Organic Compounds) – Gases released by items like paint, cleaning products, furniture, and even air fresheners. Some are harmless, while others can cause headaches or long-term health effects.
Ozone – A gas that can form indoors when certain VOCs react with sunlight or other chemicals. It’s not something you want much of inside.
RH (Relative Humidity) – The amount of water vapor in the air compared to what it could hold at that temperature.
When you only measure CO₂, you miss all the other components in the air. That’s why Dr. Taylor recommends using multiple sensors and tracking several pollutants to truly understand what’s happening.
What’s a Dog Got to Do With It?
This was one of the more surprising points. Homes with dogs tend to have more diverse microbial communities, which is beneficial. Dogs bring in microbes from outside—on their fur, paws, and even breath. These natural bacteria help keep your immune system balanced and may even reduce the risk of allergies or asthma.
Research has shown that Amish children, who grow up around farm animals and lots of natural microbes, have significantly lower asthma rates than children in ultra-clean homes—almost 90% lower.
Instead of trying to sterilize every surface, we should consider inviting healthy microbes in. This might mean designing homes with easy-to-clean floors, using fewer harsh chemicals, and ensuring ventilation doesn’t eliminate all life from your air.
What We Can Learn from Hospitals
In one hospital study, only operating rooms that met specific indoor air quality targets—such as safe levels of humidity, particles, and VOCs—were used. The result was an 87% drop in surgical site infections, without any increase in energy use. They actually saved money by optimizing air movement rather than running systems at full capacity.
This is a powerful example. With the right sensors and smart controls, buildings can protect people’s health and still be efficient.
A Smarter Way to Manage Indoor Air
Dr. Taylor described a simple yet effective system for managing indoor air quality:
Monitor: Track levels of CO₂, PM, VOCs, ozone, temperature, and humidity.
Analyze: Look for patterns. Are there spikes during certain times or activities?
Act: Adjust your ventilation, filtration, or humidity settings based on your findings.
Repeat: Continuously check, adjust, and refine over time.
Some companies are even developing tools that consolidate all this information into a single score—a kind of health rating for your air. These tools can make it easier to identify problems and communicate them to clients or team members.
From the Q&A: What People Really Wanted to Know
Can air pollution reach your brain? Yes. Tiny particles and certain chemicals can pass through your nose or bloodstream and affect your brain over time.
What happens when chemicals mix? If you spray air freshener while cooking, you might create new pollutants that are worse than either on their own.
Are current ventilation standards enough? They’re designed for comfort, not health. We need to examine actual exposure levels and compare them to medical guidelines—not just airflow.
Final Thought
This conversation reminded us that good building science is about more than keeping people warm or dry. It’s about health. It’s about creating homes and workplaces that help people thrive.
This might mean measuring air more carefully, using sensors that tell the full story, or welcoming a bit more microbial diversity. And yes, it might also mean making space for a dog or two.
Because when it comes to healthy buildings, sometimes the most surprising solutions have paws.