When heated, gas can release small particles, carbon monoxide, nitrogen dioxide, and formaldehyde into the air. When they accumulate, these pollutants can reach levels that exceed EPA aviation security standards and pose health risks.
According to a California toxicity model: “During a typical winter week, 1.7 million Californians could be exposed to levels of CO2 in excess of ambient air standards, and 12 million could be exposed to excessive levels of NO2 if they did not use hoods while cooking. "
This is why for Blazovsky and building biologist and environmental consultant Ryan Blaser, it's imperative to use an exhaust fan over and over while cooking. Blaser says you can easily tell if your device is working properly by cooking some bacon, fish, or something particularly fragrant and turning on the fan. "If you can smell bacon across the room or in another room, the fan isn't doing its job."
In this case, you should have it checked by a technician. In the meantime, open these windows and add another fan while cooking to allow cross ventilation and improve airflow. And when your gas range has reached the end of its life, dispose of it responsibly and consider replacing it with a safer, greener option like an induction range.