Smoke from the recent Californian wildfires has made the state's air quality some of the worst in the world. Aartikalyani / Getty Images Wildfire smoke can travel hundreds of miles and remains in the air for several days, and even months in rare cases. Research also suggests that the frequency and intensity of wildfire smoke waves is likely to get even worse in the coming years due to climate change. So, if you live in or around areas that have been exposed to wildfires, you need to know how to protect yourself and your home from it.When wildfire smoke is present, stay inside your home with the windows and doors closed as much as possible until the smoke clears. Using an air conditioning unit or an air purifier can also help clean out smoke particles from the air inside your home, which will help to reduce the stress on your heart and lungs. If your air conditioner is equipped with a true HEPA filter, it can work to filter smoke. If not, it could be worth investing in an air purifier. Djedzura / Getty Images If your AC unit definitely has a HEPA filter, it's also important to make sure the fresh air intake is closed when filtering for smoke. (FYI, if you're not 100% sure how to do this, it's worth speaking to a professional.) If you're looking to buy an air purifier, here are some tips that will help you choose the right one and use it to filter smoke from your home: 1. Look for an air purifier that uses true HEPA filters. John_vlahidis / Getty Images HEPA-rated filters remove 99.97% of airborne particles including smoke, pollen, and dust. They also remove 99% of odor-causing bacteria, so they're good to have in all circumstances. 2. Also look for Association of Home Appliance Manufacturers (AHAM) certification. AHAM / Via youtube.com AHAM tests the safety and effectiveness of air cleaners, and provide a clean air delivery rate (CADR), which indicates how quickly your purifier can clean the air of smoke, pollen, and dust. The CADR will also tell you how large of a room the purifier can be effective in. They recommend purchasing an air purifier that has a CADR that's about two-thirds of the room's surface area. For example, if your bedroom is 120 square feet, you'll need a smoke CADR of at least 80. 3. Avoid purchasing ozone generators that claim to purify the air. amazon.com According to the California Air Resources Board, ozone generators are ineffective at cleaning indoor air and can be dangerous to your health. They can also damage indoor furnishings that are made of fabric, rubber, or plastic. It's also worth noting that any air purifier that's AHAM-certified won't use ozone. 4. Keep your doors, windows, ducts, and fireplace dampers closed as much as possible while using an air purifier. Kritchanut / Getty Images You'll need to seal off the home against outdoor air so you aren't overloading the filter. 5. Run the purifier on the highest setting until you can no longer smell smoke. Swinsider / Getty Images Air purifiers should run continuously, but once they've cleared the pollutants, they can maintain the air quality on a lower setting. In any case, you should always follow the guidelines outlined in the unit's manual as every air purifier works differently. 6. Purchase extra filters, because you'll need to switch them out more often when filtering for wildfire smoke. amazon.com Most systems recommend switching out the HEPA and activated charcoal filters every few months. However, if they're clearing heavy toxins from the air, they may get dirtier a lot quicker, which will affect how well they work. If the air doesn't smell clean, you probably need to change the filter. 7. And keep any activities that can add smoke to the home to an absolute minimum. Tashka2000 / Getty Images Smoking, burning candles, or using a vacuum that doesn't have a HEPA filter can all make matters worse. Now, here are three highly rated and AHAM-verified air purifiers: This air purifier that's small but still gets the job done. amazon.com / Via amazon.com Promising review: "I live on a superfund site and regularly have my air quality tested. My air regularly comes back cleaner in the room where I am using this filter. I also notice less dust landing on my shelves. It's basically silent on the lowest setting. Most filters I have tried — even when running on low — are far louder than this one." —Kristine HaleGet it from Amazon for $99. This air purifier that's better for large spaces and has an automatic mode that adjusts to the needs of the environment. amazon.com The system also has four speeds that you can also control manually. It's effective for a space of 360 square feet.Promising review: "I live in a valley in Western Montana where we've been dealing with very heavy forest fire smoke all summer. It started to get so bad that smoke was making its way into our home as well. I took a chance on this air purifier and it has really helped. We leave it on day and night. It's very quiet, unless you use it on the highest setting. It's not meant for a huge room, but I usually leave it in my large living room and it does great. I highly recommend it if you are dealing with smoke from nearby fires." —missoulajennyGet it from Amazon for $130.59. And this air purifier that has over 8,000 Amazon reviews and a 4.2-star rating. amazon.com Promising review: "While I can't measure specifically how well this works, I can smell and breathe the difference. We're a few miles outside Napa, CA, and had to leave our home for a few days due to smoke from the recent fires. Now that we're back, the air is still visibly smokey outside and dangerous to breathe without an N95-type mask.This air purifier has made breathing noticeably easier in our home, and the air smells much cleaner, especially with the ultra violet light turned on. The noise level is equivalent to a small fan set on high. To me, it's a neutral, white noise-type sound, but my son doesn't like it turned on high at night." —K. WhiteGet it from Amazon for $79.99.