In an emergency, homemade simple protective tools may be at risk, but if you do need a temporary emergency plan, please be sure to note: **Homemade gas masks cannot replace professional protective equipment**, and can only be used in very short-term, low-risk environments (such as slight dust or odor) when there is no other choice. The following is a reference plan based on scientific principles. Please fully assess the risks before using it. --- ###**Material preparation** 1. **Airtight container**: 500ml plastic bottle (such as mineral water bottle, it needs to be cleaned and dried). 2. **Filter material**： -**Activated carbon layer** (charcoal fragments/particles, need to be crushed and baked at high temperature to remove impurities). -**HEPA filter cloth** (can be removed from waste air purifiers, or use multi-layer dense cotton cloth). -**Moist sponge** (used to increase aerosol adsorption). 3. **Sealing materials**: rubber band, non-toxic glue, food grade silicone (for edge sealing). 4. **Auxiliary tools**: scissors, needle and thread, tape. --- ###**Production steps** 1. **Facial fit structure**： -Cut off the bottom of the plastic bottle and keep the mouth of the bottle. -Cut out breathing holes (about 3cm in diameter) on both sides of the bottle, and the position must correspond to the mouth and nose. - Use silicone or foam strips to make a sealing ring at the edge of the bottle mouth to prevent air leakage. 2. **Filter layer assembly** (from outside to inside)： -**Outer layer**: HEPA filter cloth (blocking large particles). -**Intermediate layer**: Activated carbon (adsorbs chemical gases/odors, needs to be tightly filled but leaves an air flow channel). -**Inner layer**: Moist sponge (increase aerosol filtration, need to be replaced regularly). 3. **Fixing and testing**： - Use tape and needle and thread to fix each layer on the inside of the breathing hole. -Check the air tightness after wearing it (cover the bottom of the bottle and inhale, feeling moderate resistance and no air leakage). --- ###**Key risk warning** -**Cannot protect against toxic gases**: Gases such as carbon monoxide and hydrogen sulfide require special chemical filter tanks. -**The efficiency of activated carbon is limited**: Household charcoal has not been activated, and its adsorption capacity is less than 1/10 of that of professional materials. -**Respiratory resistance problem**: Multi-layer materials may cause hypoxia, and should not be used for more than 10 minutes. -**Disabled for children and patients with respiratory diseases**. --- ###**Better alternative** 1. **Purchase an industrial dust mask** (for example, the 3M 6200 series is about 200 yuan, and the filter cotton can be replaced at a lower cost). 2. **N95/KN95 mask**: The model that fits the face can block more than 95% of particulate matter (about 5 yuan per piece). 3. **Emergency escape strategy**: In the event of a fire or chemical leak, cover your mouth and nose with a wet towel and evacuate in a low posture, which is far more reliable than homemade tools. --- **Please remember: life safety cannot “save money”**. The design of professional protective equipment has been rigorously tested, and self-made solutions may expose you to higher risks.