Freeway pollution travels farther than we thought
Use filters, but know the limitations
If you have a central heating, air-conditioning or ventilation system, install high-efficiency air filters. They should be rated 13 or higher on the 16-point industry MERV scale (Minimum Efficiency Reporting Value) that measures how effectively they block tiny pollution particles.
Make sure to replace them on schedule, about every few months.
But filters remove only some of the harmful ingredients in traffic pollution. And they’re effective only when the air is running and all doors and windows are closed.
Most will not remove toxic exhaust gases such as benzene and 1,3-butadiene. To screen those out, you need more costly charcoal filters.
Also factor in the age of your building. Filters are less effective in older homes, which let in more pollutants, and work better in newer dwellings that seal off more outside air.
If you live in a new home near a freeway in Los Angeles or San Francisco, high-efficiency filters may already be required. And the California Energy Commission is moving to require MERV 13 air filtration in all newly constructed dwellings starting in 2020.
But those rules will do nothing to reduce pollution in existing homes, including those occupied by more than 1.2 million people in Southern California who already live within 500 feet of a freeway.
Don’t have central air? Adding one or two stand-alone air-cleaning devices to your home can help reduce particle pollution levels, so long as you keep them running 24/7. But air cleaners are effective at lowering particle levels only in a single room, not an entire home. Make sure the model you choose is certified by California regulators.