As wildfires rage up and down the West Coast, a panel of experts from Stanford University said Friday that exposure to high levels of pollution from wildfire smoke is the equivalent of smoking seven cigarettes a day.

Add to that increased risk of stroke and heart attack as well as pushing the lungs to the limit if a person is exposed to wildfire smoke and then contracts COVID-19, said pediatrics professor Kari Nadeau with Stanford University School of Medicine.

“With any type of wildfire smoke, tobacco smoke, vaping — but especially wildfire smoke because a lot of it is toxic — it’s going to strip the lungs of its already functioning immune system. The lung and the immune system is already trying to fight against the wildfire smoke,” said Nadeau. “Then on top of that you get infected, that’s going to really wreak havoc on your body and your body is going to try to respond more fervently.”

Prolonged exposure to wildfire smoke can also damage the heart and increase the risk for stroke and heart attack for the elderly. For pregnant women, it can cause premature birth and even stillbirths.

Record-breaking poor air quality readings for the West Coast have stacked in the last several weeks. Much of the smoke seen in the San Francisco Bay Area and northern San Joaquin Valley is from the largest wildfire in recorded California history, the August Complex, which was sparked by numerous lightning strikes in mid-August. The fire has burned over 839,000 acres and stretches across multiple counties including Glenn, Lake, Mendocino, Tehama and Trinity.

Earlier this month, Los Angeles reported some of the highest levels of ozone pollution it’s seen in 26 years.

Civil and environmental engineering professor Lynn Hildemann said the size of smoke particles that come off a wildfire are unique and can penetrate deeply into the lungs. Then there’s the concern about breathing smoke that’s a couple days old versus breathing fresh wildfire smoke, said Hildemann.

“Breathing in a certain AQI level of wildfire smoke particles is having more of a health effect than breathing in a normal mix of particles from outdoors,” said Hildemann. “After they’re emitted into the atmosphere, they undergo further chemical reactions. The type of reactions may change their toxicity, it certainly makes it easier for your body to take in the organic particles of the smoke particles.”

Nadeau said it’s important that people stay informed on what their local Air Quality Index (AQI) is on any given day. The U.S. Environmental Protection Agency’s reporting metric ranges from zero to 301 — though monitoring stations can and do measure levels much, much higher — and is color-coded. Readings zero to 50 qualify as “good” air quality, marked green.

“We know that an AQI measurement of about 20 is equivalent to smoking one cigarette a day,” said Nadeau. In the last week, Northern California residents have been exposed to readings of 150 — “unhealthy” — and higher.

“That’s equivalent to seven cigarettes a day,” said Nadeau.

Associate earth system science professor Marshall Burke said the high levels and duration of poor air quality on the West Coast are unprecedented and are going to be an issue for other parts of the world.

“If folks have seen the nice animations of this or the terrible animations of the plumes blowing across the rest of the U.S.,” said Burke. “So, this is not just a U.S. West Coast issue but a U.S.-wide issue.”

Burke said compared to other parts of the world, San Francisco Bay Area residents breathe relatively clean air and there’s a huge global disparity compared to developing nations.

“In the last few weeks, we’ve experienced what it’s like to live in many parts of the rest of the world. San Francisco, Portland, Seattle for a few days had some of the worst air quality in the world,” said Burke.

The panel discussion was led by professor Chris Field. The panel on the Stanford Woods Institute for the Environment webinar agreed wearing an N-95 mask can help reduce exposure to certain particles and people should avoid outdoor activities.

— By Nathan Solis, CNS