
Charcoal bags should be discarded after 2 to 3 months of use in the car. Over time, the activated charcoal inside becomes saturated and loses its absorption capability, at which point it can be thrown away. Activated charcoal is a microcrystalline carbon material made from carbon-containing substances. It appears black in color, has a highly developed internal pore structure, a large surface area, and strong adsorption capacity, making it a commonly used adsorbent, catalyst, or catalyst carrier. Activated charcoal can be categorized by raw material source into: wood-based activated charcoal, shell-based activated charcoal, animal bone and blood activated charcoal, mineral-based activated charcoal, synthetic resin activated charcoal, rubber and plastic activated charcoal, and recycled activated charcoal. By appearance, activated charcoal can be classified into: powdered, granular, irregular granular, cylindrical, spherical, and fibrous forms.

I've been using charcoal bags to remove odors in my car for over ten years, usually replacing them every three months. When the car is new and the smell is strong, I double the amount of charcoal bags and replace the first batch after a month. During the hot summer months when the car is exposed to high temperatures, extra attention is needed as the charcoal saturates quickly—it needs to be taken out and sunned every two weeks. However, it shouldn't be reused too many times because the pores of the activated charcoal can get clogged. I repurpose the old charcoal bags in the shoe cabinet, but I always use new ones in the car. When buying charcoal bags, remember to choose coconut shell charcoal for its high cost-performance and strong adsorption capacity.

Activated carbon packs should be discarded after a maximum of six months within their validity period. The principle of activated carbon adsorption involves micropores capturing formaldehyde molecules. During the first three months of use in a new car, the adsorption rate exceeds 70%, but it drops sharply afterward. I have tested carbon packs used for six months, and their adsorption capacity was only 10% of that of new packs, potentially releasing pollutants instead. It is recommended to use an air quality monitor to track the PM2.5 levels in the car. Replace the packs when the readings show an abnormal increase. Additionally, although exposing used carbon packs to sunlight can partially restore their capacity, they should not be reused more than twice.

As a mother of two, I prioritize in-car air quality the most. Charcoal bags can typically last for three months under normal conditions, but when there are child seats and food crumbs in the car, I recommend replacing them every two months. I opt for charcoal bags with color-changing indicators—when the blue turns brown, I replace them immediately. Especially after heavy rain when the car interior gets damp, if the charcoal bags become moist and moldy, they should be discarded right away. I always keep three spare packs in the trunk and try to park away from high-temperature areas to extend the lifespan of the charcoal bags.


