In some cities, smog is seen as part of the weather and a regular part of daily conversation. In Los Angeles, the city that made photochemical smog famous, the forecasts include a smog report, just like any other weather condition.

On particularly smoggy days in the inland valleys, one can clearly smell the ozone associated with some kinds of smog, especially in the morning, when the air might otherwise smell of eucalyptus or desert flowers in bloom.

Any form of air pollution that creates a haze and reduces visibility can be called smog. While automobiles get blamed for producing smog, the term actually dates back to the early 1900s to describe any mix of smoke and fog. In those days, the smoke usually came from burning coal, so it was especially common in industrial areas.

Today, much of the smog that people talk about is photochemical smog. Photochemical smog is created by a chemical reaction between sunlight, nitrogen oxides and at least one volatile organic compound (VOC) in the atmosphere. Sources of nitrogen oxides include car exhaust, coal power plants, and factory emissions. VOCs are released from gasoline, paints, and many cleaning solvents. When these chemicals are exposed to sunlight, which L.A. has plenty of, they form airborne particles and ground-level ozone, and smog is born.

High up in the atmosphere, the helpful ozone layer protects us from the sun’s dangerous ultraviolet radiation. But when ozone is close to the ground, ozone can damage lung tissue. It is especially unhealthy for children, whose lungs are developing, and for people with respiratory illnesses like asthma. Ozone can also cause itchy, burning eyes. The smell is a little like chlorine bleach.

Smog often includes fine particles from diesel emissions. These PM 2.5 particles, which can be found in the air on smoggy days, are small enough to penetrate deep into the bloodstream through the lungs and cause serious health issues. In China, it is estimated that pollution is responsible for one in five of the 250,000 premature deaths annually.

Cities like Los Angeles, located in basins surrounded by mountains, have especially bad smog problems because the smog is trapped, so it cannot be carried away by wind. An inversion layer, where warmer air is on top of cooler air, acting like a lid as pollution builds up.

Summer and autumn are the worst times for smog in L.A. because that is when inversion layers most often occur. In China, winter is the worst season, with the northern cities being smoggier than southern ones, because of all the coal that is used for industry and household heating. The demands for energy soar in the colder months, while the naturally overcast weather traps the pollution beneath the clouds.

So how to protect your loved ones, your pets, your plants and yourself from effects of smog pollution? If, like most people, moving to a town with fresher air or fleeing to a holiday home during smog season is not an option, your best bet is to reduce your household’s daily exposure to smog with an effective air purifier for haze and smog.

Purifying your air has an especially healthy impact in the bedroom at night, when your lungs are more vulnerable and where you spend a third of your time. Even people who do not live with smog pollution find that fresh, clean air helps them sleep more deeply and wake up more refreshed.

The best smog air purifiers are those that remove both particles and gases. Blueair air purifiers with HEPASilent™ technology deliver especially high performance and efficiency against smog by combining electrostatic and mechanical filtration technologies. This technology, pioneered by Blueair, achieves a 99.7% filtration efficiency of airborne particles down to 0.1 micron in size*, while delivering a high Clean Air Delivery Rate (CADR), whisper-silent operation and high energy efficiency. In fact, a Blueair air purifier works so quietly that you can not only sleep next to it, you might even have to check to make sure it is switched on. And on its lowest setting, a Blueair air purifier uses less electricity than a lightbulb.

HEPASilent™ technology can be combined with filters containing activated carbon to effectively remove traffic exhaust, smog and airborne chemicals, VOCs plus PM2.5.

Using approximately 2-4 lbs of activated carbon, formulated with magnesium dioxide and copper oxide, the carbon-activated SmokeStop™ filter is excellent at trapping smog, dangerous chemicals and odors. The high volume and weight of the carbon, plus the low-density design and large surface area of the mechanical filter medium, mean the filters last a long time without becoming clogged. And for ultimate smog and gas removal, you can use a Blueair DualProtection™ filter with powdered, high-porosity coconut carbon.

Besides making your own air fresh and clean, you can also do your part to reduce smog by changing behaviours. National Geographic provides a helpful list.

• Drive less. Walk, bike, carpool, and use public transportation whenever possible.
• Take care of cars. Getting regular tune-ups, changing oil on schedule, and inflating tires to the proper level can improve gas mileage and reduce emissions.
• Fuel up during the cooler hours of the day—night or early morning. This prevents gas fumes from heating up and producing ozone.
• Avoid products that release high levels of VOCs. For example, use low-VOC paints.
• Avoid gas-powered yard equipment, like lawn mowers. Use electric appliances instead.

*Tested on particles down to 0.1 micron according to EN1822.