A methane gas leak in the Los Angeles neighborhood of Porter Ranch has driven 1,600 residents from their homes since the leak was discovered in October, according to several media reports. Governor Jerry Brown has declared a state of emergency, and the Federal Aviation Administration (FAA) designated the area a no-fly zone in response to fears that fumes from the leak could be ignited from the air, CNN reports.

The leak is coming from one of the wells of a gas storage facility in the Santa Susana Mountains. In December, the Southern California Gas Company said the leaky well would take three to four months to seal.

Here's what to know about gas leaks and how they can affect your health.

What is methane?

Methane is the primary component in natural gas, which many homes use for fuel. It's odorless, but any gas provided for home use contains smelly chemicals to make leaks noticeable, according to the California Office of Environmental Health Hazard Assessment (OEHHA).

That "rotten egg” smell is your first clue about a methane gas leak, according to the Virginia Department of Health. If you notice it, go outside to get fresh air and notify the fire department right away, as methane is highly flammable.

According to Con Edison, other signs of a gas leak are:

  • A white cloud, mist, fog, bubbles in standing water, blowing dust or vegetation that appears to be dead or dying for no reason.
  • Roaring, hissing or whistling.

Related: What to Do if You Smell Gas

Symptoms of exposure

If a natural gas leak has occurred and is severe, oxygen can be reduced, causing dizziness, drowsiness, nausea, headache, and irregular breathing. Large amounts of methane in the air will decrease the amount of oxygen available, according to the Wisconsin Department of Health Services. OEHHA has fielded “several” complaints from residents reporting recurring health issues as a result of the gas leak.

Gabriel Khanlian told TIME his 6- and 8-year-old sons were suffering from headaches and nausea, and his 2-year-old daughter developed rashes on her body.

Brian and Christine Katz say their 2-year-old daughter "spent four nights in intensive care for 'upper respiratory symptoms' with no prior health problem," according to a lawsuit filed against the gas company. "She experienced some form of seizure and is now listless, suffering from persistent rashes, and painful nausea."

If you suspect your family has been exposed to methane gas, see your doctor right away.

Related: Do You Know the Symptoms of Carbon Monoxide Poisoning?

A greenhouse gas

Methane is a greenhouse gas, a type of gas most experts agree contributes to climate change. According to the Environmental Protection Agency, it's the second most prevalent greenhouse gas emitted in the United States from human activities. If it leaks into the air before it’s used, such as from a crack in a pipe, it absorbs the sun’s heat and warms the atmosphere, according to the Environmental Defense Fund.

The Porter Ranch leak is releasing methane at a rate of 30,300 kilograms per hour according to the most recent measurements by the California Air Resources Board. The Los Angeles Times puts that number in perspective:

“At its height, the leak more than doubled the methane emissions of the entire Los Angeles Basin and surpassed what is released by all industrial activity in the state. Experts say the release of so much methane, a fast-acting greenhouse gas many times more powerful than carbon dioxide, means that the biggest environmental consequence of the leak will be its effect in boosting global warming. Long after the leak stops and the foul odors vanish, the pulse of methane will remain in the atmosphere and its damage to the climate will go on.”

Angela is a Pulitzer Prize-winning digital editor with more than 15 years of experience delivering news and information to audiences worldwide. Prior to joining SafeBee, she was the features editor for Boston.com at The Boston Globe, overseeing health, travel, entertainment, business and lifestyle coverage. Before moving to features, she was the news and homepage editor, covering stories such as the Boston Marathon bombing, Red Sox World Series victories, presidential elections, a papal inauguration, and more. Her favorite safety tip: Clean your phone! The average cell phone has 18 times more germs than the toilet handle in a men’s restroom.