Do fireplace heaters emit harmful gases that affect indoor air humidity?

Fireplace heaters are the first choice for many people to keep warm in cold seasons, especially traditional gas fireplaces and modern electric fireplaces. They not only provide comfortable indoor warmth, but also create a warm family atmosphere. However, when using a fireplace heater, one of the concerns of many people is whether it will emit harmful gases and affect the indoor air humidity. This issue is not only related to indoor air quality, but also to the health of family members, so it is necessary to understand in detail the working principle of the fireplace heater and its possible impact on air quality.
Regarding the emission of harmful gases, gas fireplace heaters are the most concerned type. Gas fireplaces usually heat indoor air by burning natural gas or liquefied petroleum gas (LPG). During the combustion process, gas fireplaces will emit a certain amount of exhaust gas, mainly including carbon dioxide (CO₂), water vapor (H₂O) and possibly a small amount of harmful gases such as carbon monoxide (CO) and nitrogen oxides (NOx). If the ventilation system of the gas fireplace is not perfect or improperly installed, these harmful gases may accumulate indoors, affecting air quality and even posing a threat to health. Especially in closed spaces, in the absence of adequate ventilation, the concentration of harmful gases such as carbon monoxide may rise, leading to poisoning or respiratory diseases.
To reduce these safety hazards, modern gas fireplace heaters are usually equipped with flues or ventilation systems to ensure that exhaust gases can be discharged outdoors in a timely manner. Proper installation and maintenance are essential to ensure that chimneys and exhaust ducts are unobstructed to prevent harmful gases from leaking into the room. Even so, when using a gas fireplace, it is still necessary to regularly check and clean the exhaust system to ensure its normal operation and prevent exhaust gases from flowing back into the room.
Unlike this, electric fireplace heaters do not produce harmful gases like gas fireplaces. Electric fireplaces use electrical energy to heat the internal heating elements, and then transfer the heat to the indoor air through radiation or convection. Because it does not rely on the combustion process, electric fireplaces do not produce harmful gases such as carbon dioxide or carbon monoxide. Therefore, from the perspective of harmful gas emissions, electric fireplaces are safer than gas fireplaces. However, the electric heating process of electric fireplaces may also have a certain impact on air humidity.
The heating method of electric fireplaces usually causes the air temperature to rise, and the increase in hot air is often accompanied by a decrease in air humidity. Because electric heating does not essentially increase the moisture in the air, it will accelerate the evaporation of moisture in the air, causing the indoor air to become dry. This dry air may cause some health problems, especially for people with dry skin and sensitive respiratory systems. Long-term exposure to dry air may cause uncomfortable symptoms such as difficulty breathing and dry skin.