As wildfires worsen and air quality plummets across many parts of the country, people are getting creative about protecting their lungs. One viral DIY trend that’s gained traction in recent years is a makeshift air purifier built by attaching HVAC filters to a box fan. Touted as an affordable solution, especially in emergencies, it’s an idea rooted in good intentions—but it comes with some serious drawbacks.
While a DIY air purifier might seem like a clever hack in a pinch, it’s important to understand why this cobbled-together setup isn’t a substitute for a purpose-built, high-performance air purifier.
1. Inconsistent Build Quality and Safety Risks
The biggest flaw of a DIY air purifier is that it relies entirely on DIY assembly. That means no two builds are exactly alike, and small construction mistakes can have big consequences. If filters aren’t sealed tightly around the fan’s edges, air can bypass them completely, reducing effectiveness. And since box fans aren’t designed to work with resistance-heavy filters, pushing air through them can strain the motor—causing overheating or even creating a fire hazard if left running for long periods.
Most box fans aren’t engineered with safety shutoffs, sealed motors, or fire-resistant materials. In fact, the U.S. Consumer Product Safety Commission has warned against using box fans in a way they weren’t designed for, especially near flammable materials or during sleep.
2. Lower Filtration Performance
In tests comparing a fan-and-filter combo to real HEPA air purifiers, the difference is striking. A well-built DIY air purifier might reduce airborne particles by 60–87% in the first 30 minutes—but that’s still a far cry from the 99% or more removal rate delivered by high-quality HEPA purifiers.
And keep in mind: this DIY setup only works when filter airflow isn’t obstructed. They may even blow unfiltered air into your space if air begins to leak through gaps or push around the filters instead of through them.
3. Long-Term Costs
At first glance, the DIY route seems cheaper. But over time, costs can balloon.
- Frequent filter replacements: MERV 13 furnace filters used in DIY air purifiers need to be replaced often—sometimes every few weeks during wildfire season—because they clog faster and lose efficiency over time.
- Higher energy use: Box fans are not optimized for efficiency. They draw more power than most commercially manufactured HEPA purifiers, which are designed to run continuously and quietly for years.
- Fan burnout risk: Constant strain from pushing air through thick filters can shorten your fan’s lifespan—meaning you might be replacing the whole setup more often than expected.
4. No Gas or Chemical Filtration
Smoke pollution isn’t just about particles—it also includes harmful gases and volatile organic compounds (VOCs), especially during wildfire events. When vegetation, homes, plastics, and household materials burn, they release a toxic cocktail of chemicals into the air.
There is no DIY option that does anything to remove these gases. That’s a major gap in protection, especially for people with respiratory illnesses, asthma, or chemical sensitivities. Even short-term exposure to wildfire gases can trigger coughing, wheezing, headaches, and fatigue. Long-term exposure has been associated with chronic inflammation, oxidative stress, and elevated risks of heart and lung disease.
High-quality air purifiers, like those made by Austin Air, combine true medical-grade HEPA with large volumes of activated carbon and zeolite to capture both particles and gases. This layered approach is essential during wildfire events, when invisible gases can linger indoors long after the smoke has cleared. DIY boxes may reduce visible haze—but they leave the most hazardous components in the air.
5. Not a Long-Term Solution for Clean Indoor Air
DIY air purifiers are often promoted as “better than nothing”—and that’s true. In a short-term emergency, when your only options are limited, a DIY filter taped to a fan might help reduce some particulate exposure. But this is not a sustainable solution for long-term health and safety.
Just as you wouldn’t build your own seatbelt or rely on duct-taped plumbing, indoor air quality—especially in the face of climate change and smoke pollution—isn’t something to gamble on. Your lungs deserve better.
Invest in Real Protection
For dependable, long-lasting air quality improvement, invest in a purifier that’s built for the job. Units like the Austin Air HealthMate Plus use solid steel housings, medical-grade HEPA, and large beds of activated carbon impregnated with potassium-iodide and zeolite to provide comprehensive protection from both particles and gases—including wildfire smoke. Plus, they’re made in the USA and designed to last for years with minimal maintenance.
A DIY air purifier might be a temporary Band-Aid during a crisis—but it’s no match for a professionally engineered air purifier. Clean air is a necessity, not a luxury. Don’t leave your health in the hands of duct tape.
