This month, strong Santa Ana winds sparked massive wildfires in Ventura County, and stunning images of orange skies over Oxnard reminded us of the San Francisco Bay Area in 2020. Although the Mountain Fire is now mostly contained (along with the Sandy Fire in Monterey County), it is the most destructive fire to hit Southern California in six years, with fires spreading beyond Ventura toward Santa Barbara and beyond. polluted the air. Santa Ana winds and a prolonged fire season could cause smoke to spread again in Southern and Northern California into November and December, as happened in 2017 and 2018.
And this isn’t just a West Coast problem. The Northeast is facing its worst fire season in more than a decade, prompting evacuations in New York over the weekend.
In affected areas, residents urgently need to protect themselves from inhaling wildfire smoke, whose composition is comparable to second-hand smoke without nicotine. Harmful smoke particles can cause or worsen heart and lung disease even miles away.
The South Coast Air Quality Management District recommends staying indoors and using an air conditioner or air purifier. This general advice is helpful, but not sufficient. There are five specific steps you can take to safely limit exposure to extreme levels of toxic particles during large fires like this.
First, please let me know. Local air quality monitors, the PurpleAir Community Scientist Network, and other online services can help you get a clear picture of particle pollution in your area. Handheld and desktop personal particle monitors are also available for purchase. You can’t rely on the color of the sky. The color of the sky can be deceiving. In 2020, wildfires turned San Francisco’s skies a deep orange, but air quality actually worsened after the sun returned and skies looked more normal. Because by that time the smoke particles had fallen. Close to the ground, in the air that people breathe.
Next, stay indoors and close your windows and doors. This can cut your exposure to outdoor pollution in half.
But particles can still seep through cracks, and closing windows and doors also traps exhaled air, increasing the risk of spreading respiratory illnesses like COVID-19 and influenza. That leads to the third important step. That means removing outdoor pollutants and potentially dangerous breath particles that enter your home.
Central ventilation, even with filters, usually requires the addition of an appropriately sized indoor air purifier. In 2023, the Centers for Disease Control and Prevention recommended ventilation at least five times per hour for occupied indoor spaces, and this month the California Department of Public Health reiterated this recommendation specifically for classrooms.
The number of air purifiers needed to achieve this goal depends on the size of the room, the model of the air purifier, and the speed and noise level that the user can tolerate from the air purifier. High-efficiency particulate air (HEPA) purifiers operating at 5 to 10 air exchanges per hour cost between $1 and $5 per square foot for typical ceiling heights and reduce indoor particulate exposure. can be reduced by 10 to 50 times compared to outdoors, depending on the environment. The percentage of particles that enter the room even after the doors and windows are closed.
If you can’t install a purifier for the whole house, you can focus on making at least one room safe, such as your bedroom. A low-cost (approximately $20) infrared motion switch connected to an air purifier turns on the air purifier when a person enters the room and turns it off after a period of time when the person leaves, reducing power. You can save money and extend the life of your filter.
HEPA purifiers are often sold out during peak wildfire season. The DIY purifier can be built in 10 minutes using more consistently available components: a box fan and MERV 13+ furnace filter sold online, and costs typically 5 to 10 times less than HEPA options. is. Or even if your store or online inventory only has low-grade filters, some use of filters is much better than none at all.
Fourth, in addition to indoor safety, if you need to drive in smoky conditions, you can switch your car’s air system to recirculation. As a long-term solution, many cars also allow you to upgrade your cabin air filter to a HEPA model.
Finally, wear a reusable elastomer mask, such as an N95, N99, or P100, both outdoors and indoors without air purifiers. All of these masks are designed to reduce exposure to particles from wildfire smoke by at least 20 times while fresh. And it fits well. If this is difficult to wear, especially in hot weather, ventilated industrial helmets with battery-powered fans and filters can be more comfortable (but tend to be more expensive, starting at around $450) ).
As climate change intensifies, wildfires are likely to become more frequent and severe. Taking these precautions against wildfire smoke also protects against airborne threats such as respiratory illnesses and pollution in general. Don’t wait until the sky turns orange to take action.
Devabhaktuni Srikrishna is an electrical engineer, founder of the air quality website www.patientknowhow.com, and vice president of control and mitigation at the American Assn. Aerosol Research Annual Conference.
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