Hesperian Health Guides

Disinfecting with Heat

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HealthWiki > A Community Guide to Environmental Health > Chapter 19: Health Care Waste > Disinfecting with Heat

Many health centers use autoclaves or microwaves to disinfect syringes, other medical tools, and some waste. If you have no autoclave or microwave, then boiling, steaming, or pressure steaming materials for at least 20 minutes will disinfect them. Disposable wastes should not be disinfected with tools that will be used again, because it is difficult to keep the reusable tools clean when you separate them after disinfection.

Wear gloves and a mask to cut plastic and cloth items such as catheters, IV bags, tubing, large bandages, and so on into small pieces.

How to make sure items are disinfected

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For boiling, steaming, and pressure steaming, start to count the 20 minutes after the water is fully boiling. Do not add anything new to the pot once you begin to count. After 20 minutes, turn off the heat and let it cool.

Materials that will be reused after they are boiled or steamed must be removed using sterile gloves or tongs, placed right away inside a disinfected container, and then sealed. The boiled water can be safely poured down a drain.

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You can use boiling to disinfect metal, rubber or plastic tools, and cloth. After you wash and rinse the tools, put them in the pot, cover the tools with water, bring the water to a boil, and boil for 20 minutes.

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You can use steaming to disinfect gloves, masks, and things made of metal and plastic. The water does not need to cover everything in the pot, but you must use enough water to keep steam coming for 20 minutes. The pot should have a lid that fits tightly.

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Pressure steaming

Use pressure steaming to disinfect metal, rubber, plastic, and cloth. Wash and rinse the materials to be disinfected and put them in the pressure cooker with water. Close the lid and heat it on the stove. After it boils, cook at 15 to 20 pounds of pressure for 20 minutes.


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An autoclave is a small machine that disinfects things using steam heat and pressure. Autoclaves have been used for many years to disinfect medical instruments. They are used more and more to treat waste as well.

It is safest to use 2 separate machines — one for reusable instruments and one for waste. For health centers with very small amounts of waste to be disinfected, a pressure steamer is less expensive and works as well as an autoclave. It is possible to build gas, kerosene, or solar-powered autoclaves for areas with no electricity.

Microwave ovens

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Microwave ovens heat the moisture in objects placed inside them. The heat, together with the amount of time an object is in the microwave oven, leads to disinfection. Because microwave ovens vary greatly in power, use care when disinfecting with this method. To make sure of high level disinfection: 1. Put the waste in a non-metal container with enough water to cover it. 2. Put a loose-fitting cover over the top of the container to reduce the loss of water during heating. 3. Microwave waste materials for at least 20 minutes. 4. Let the container cool before opening. Dispose of any microwaved liquid waste in a leaching pit or you can safely pour it down the drain.

IMPORTANT! Do not put metal objects in a microwave oven. It can ruin the machine.