How dangerous is wildfire smoke? ‘Spare the Air’ alert issued in Northern California

Flames aren’t the only threat that comes with wildfires.

Blazes also unleash smoke that contains harmful gases and fine particulate matter, threatening those who breathe it.

Fires raging this week across California have already led to “Spare the Air” alerts and warnings that older people, children and those who are sensitive to smoke should remain indoors. The entire San Francisco Bay Area was under a “Spare the Air” alert Monday as winds threatened to blow harmful smoke into the heavily populated region.

“Air quality is expected to be unhealthy Monday due to smoke from the Kincade Fire and potentially other local fires,” Jack Broadbent, executive officer of the Bay Area Air Quality Management District, said in a statement. “It is critical that residents follow evacuation orders and instructions from local health officials to protect their health.”

But just how dangerous is smoke from the Kincade Fire and other California blazes, and how can people protect themselves? Here are some answers.

How harmful is breathing wildfire smoke?

Wildfire smoke worsens an area’s Air Quality Index (AQI), which measures the level of particulate matter less than 2.5 micrometers in diameter that is in the air.

When the AQI rises above 100, it’s unhealthy for sensitive groups, while an AQI above 150 isn’t healthy for anyone to breathe, according to the U.S. Environmental Protection Agency. Air quality in Berkeley hit 158 on Monday morning, and air quality in Oakland was nearly as bad, Bay Area Air Quality Management District readings showed.

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“Researchers at UC Berkeley devised an equation that translates AQI into the rough number of cigarettes one would have smoked just by breathing the polluted air,” SFGate reports. “One cigarette per day is the rough equivalent to a PM2.5 level of 22 μg/m3, the researchers explain in their study.”

SFGate reported that “this means that if the AQI registers at 22, the amount of toxic air particles you inhale throughout the day would be equivalent to smoking a single cigarette.”

The researchers said average U.S. air pollution is comparable to smoking .41 cigarettes daily, SFGate reported.

What’s in wildfire smoke?

The smoke that wildfires spew is “made up of a complex mixture of gases and fine particles,” which are products of wood and other organic materials that fuel blazes, according to EPA.

The U.S. Forest Service warns that “the chemicals in smoke that cause the most hazard to human health are carbon monoxide, aldehydes, and tiny particles of solid matter that are small enough to be inhaled.”

“If you’re close to the fire, you’ll be exposed to carbon monoxide, which poisons your red blood cells and interferes with oxygen uptake, [as well as] nitrogen dioxide, which dissolves in the airway lining fluid to generate a powerful acid that hurts small airways,” said Dr. Brian Christman, a volunteer spokesperson for the American Lung Association, according to AccuWeather.

But of the components of fire smoke, particulates are the biggest concern, the Forest Service said, explaining that “carbon monoxide, aldehydes, and the hundreds of other compounds emitted by wildland fires are found in very low concentrations at short distances away from a fire.”

What are the health impacts of breathing smoke?

“Smoke can irritate the eyes and airways, causing coughing, a dry scratchy throat and irritated sinuses,” the Bay Area Air Quality Management District said in its “Spare the Air” alert Monday. “Elevated particulate matter in the air can trigger wheezing in those who suffer from asthma, emphysema or COPD.”

EPA warns that “microscopic particles can penetrate deep into your lungs. They can cause a range of health problems, from burning eyes and a runny nose to aggravated chronic heart and lung diseases.”

“Exposure to particle pollution is even linked to premature death,” EPA says.

How can people protect themselves from smoke?

Staying indoors and leaving an area where smoke is heavy are recommended, particularly for those who are sensitive to smoke, pregnant or young, according to EPA.

“If you are advised to stay indoors, take steps to keep indoor air as clean as possible. Keep your windows and doors closed — unless it’s extremely hot outside,” EPA advises. “Run your air conditioner, if you have one. Keep the filter clean to prevent bringing additional smoke inside. Open windows to air out the house when air quality improves.”

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Wearing paper “dust masks” while outside won’t protect a person’s lungs from fine particulates, according to EPA, and “particulate masks known as N-95 or P-100 respirators will help, but they must fit well and be used correctly.”

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Jared Gilmour is a McClatchy national reporter based in San Francisco. He covers everything from health and science to politics and crime. He studied journalism at Northwestern University and grew up in North Dakota.