This sounds like one of those “law enforcement life hacks” that gets circulated without much context—and in this case, it’s not really a standard or recommended practice.
The idea behind putting a glass of salt in a vehicle usually comes from salt’s ability to absorb moisture from the air. In theory, that could help reduce dampness inside a car, which might slightly reduce fogging on windows or musty smells.
But in real-world use, it’s not a great idea:
- Spills are a big risk: A loose glass in a moving vehicle can tip over easily.
- Corrosion issue: Salt is highly corrosive. If it spills, it can damage metal parts, seat rails, and electronics under carpets.
- Limited effectiveness: A small open container of salt doesn’t meaningfully dehumidify a car interior compared to proper products.
- Better alternatives exist: Commercial desiccant packs (silica gel or calcium chloride-based moisture absorbers) are designed for this purpose and are much safer.
Law enforcement “tips” that spread online are often either misunderstood versions of practical habits or outdated field tricks that don’t translate well to everyday civilian use.
If your goal is reducing fog or moisture in a car, safer options are:
- Silica gel moisture absorbers
- Proper ventilation / AC use (even in winter)
- Checking for water leaks or wet floor mats
So: the salt idea is rooted in a real principle, but the execution (a glass of salt in your vehicle) is more myth than useful practice.
