Heaters that are made of stainless steel rather than iron can leak heavy metals such as chromium and nickel, which can then be circulated through the heated air and breathed in, causing damage to the body.
To hear the air, flames that can reach more than 1000 °C and 3000 °F are used, and these flames can vaporize the material that the heater is made out of. Check the material that your heater is made from, and make sure it doesn’t contain heavy metals, or any other toxic material that can be vaporized, or release fumes at high temperatures.
The image above shows an example of how the material the heater is made from can be corrupted over time by the extreme heat of the flames, leading to the release of vaporized metal particles into the air. Below is an image of an unused heater for comparison.
