How dangerous is inhaling glass fibers from a car’s air filter?

Most people never think about what’s inside an air filter—until they start coughing or itching after touching one. The fear of inhaling microscopic glass fibers is real, especially for those who install filters every day.

Inhaling glass fibers from certain air filters can cause irritation, coughing, or long-term health concerns. That’s why more automotive professionals now switch to glass-free, synthetic media filters for safer handling and cleaner air.

Some filters are safer than others. The difference comes down to materials. Let's talk about it.

Are fiberglass air filters dangerous?

People get nervous when they hear the word “fiberglass.” Rightly so. In the past, some air filters—especially cheaper or industrial ones—used fiberglass media. When handled roughly, these filters can shed fibers into the air. That’s not good for lungs, eyes, or skin.

Yes, fiberglass air filters can pose health risks if the fibers are released during handling or installation. While not as dangerous as asbestos, glass fibers can cause irritation or respiratory discomfort when inhaled.

Why fiberglass can be a problem

Many manufacturers once used fiberglass because it’s cheap and traps particles well. But there’s a trade-off:

I remember working with a distributor who was worried about this exact issue. His team didn’t like handling filters that made them itch or cough. We offered our synthetic air filters with reinforced fiber media—no glass involved. That switch gave them confidence. His clients noticed, too.

At Runex Auto, our filters use advanced, layered synthetic media. It traps dust, pollen, and debris better than fiberglass, but doesn’t break down or release loose fibers. That makes them safer, especially for teams that unpack and install hundreds of units every month.

Can a bad car air filter make you sick?

Most people don’t connect air filters to health. But if you’ve driven long enough, you’ve probably breathed in air from a clogged or dirty filter. You might have even gotten a headache or started sneezing without knowing why.

Yes, a clogged or degraded car air filter can allow harmful particles into the cabin or engine, which may affect your health, especially if you're sensitive to dust, mold, or allergens.

What happens when an air filter fails?

A bad filter doesn't just stop working—it becomes a hazard:

One time, a client called me in frustration. His warehouse staff started coughing after unpacking new filters. Turned out, those filters were fiberglass-based and packed in poorly sealed boxes. We replaced them with Runex's non-glass synthetic filters⁴. Not a single complaint since. He now insists on synthetic for all rebranded stock.

We also vacuum-seal our filters in dust-free packaging. That keeps the media clean and prevents degradation during shipping or storage. The less exposure before use, the better the performance—and the fewer health risk⁵s.

Are car air filters made of fiberglass?

This question comes up often, especially when procurement teams review specs. Many lower-cost filters still use fiberglass media to keep prices down. But synthetic options are becoming the new standard, especially among high-performance brands.

Some car air filters still use fiberglass media, but many manufacturers—including Runex Auto—have transitioned to synthetic alternatives that are safer, more efficient, and eco-friendly.

Filter media matters more than you think

Here’s a breakdown of what filters are made from today:

At Runex Auto, we use high-quality synthetic fiber media. This choice wasn’t random. Synthetic materials resist moisture, don’t shed fibers, and last longer under heat and pressure. They also trap fine particles better, which means better air quality for both engines and passengers.

We made this change because we listened. Distributors like Joe Rich don’t just want “good enough.” They want consistency, safety, and performance—especially when rebranding or distributing filters under their own name.

Can car air filters get moldy?

This one surprises people. But yes, mold can grow inside a car air filter. Especially if the car is parked long in damp conditions or if the filter is made from paper or cellulose.

Yes, car air filters can grow mold if exposed to moisture and not replaced regularly. Moldy filters can spread spores into the cabin, creating an unhealthy breathing environment.

Why moisture + time = mold

Mold needs three things to grow: moisture, warmth, and organic material. Sadly, most engine bays offer all three. Add in a cellulose filter and you've got a problem:

With Runex synthetic air filters¹⁰, mold is much less likely. Our materials don’t absorb water like paper. Even in humid storage or during seasonal changes, they stay dry and firm. That’s why more of our clients now pre-order synthetic filters before the rainy season.

Also, our filters are precision-sealed. This stops water from seeping into the filter layers during transit or storage. No hidden mold surprises for your team or your end customers.

Conclusion

Inhaling glass fibers from car air filters¹¹ isn’t just an installer’s concern—it’s a quality issue that impacts everyone in the supply chain. Fiberglass filters might be cheap, but they’re no longer the safe or smart option. At Runex Auto, we’ve shifted to synthetic filter media that protects people, cars, and reputations. For distributors and procurement managers like Joe Rich, that means safer handling, happier teams, and customers who trust the products they receive.