Dr. Bob Lutz and Julie Oliver: Clean air in winter needs our attention

The raging fires in Australia continue to hammer home the effects of our climate changing, which often have significant impact on the health of everyone, especially those most vulnerable. Air quality has been hazardous, and as we’ve learned in our recent past, there are problems associated with acute and/or prolonged exposure to smoke. While this past summer was fortunately not like the previous two, the potential exists to find ourselves smothered again by the pall of burning forests that occur locally, regionally and even internationally.

We may think this isn’t a problem once the snow falls, but wood smoke is also a health concern in many of our neighborhoods during winter. To understand why, some meteorology basics are necessary.

Normally, the greater the altitude, the lower the temperature. During the winter, when the sun is lower in the sky and air temperatures are cooler, surface inversions can develop. These usually occur when the conditions are just right – calm winds, clear skies and long nights. As night falls, ground temperatures decrease rapidly. Clear skies increase the rate of surface cooling, and the long nights extend this process.

If there’s a breeze, the layers of air circulate, and the warmer air above can move lower. If not, however, a cap of warm air sits on top.

Winter inversions are often greater than those in the summer, but they’ll usually weaken during the day as temperatures increase. If, however, there’s high pressure over the area, inversions can persist until there’s a change in the weather. That’s why some communities, often in valleys, temporarily restrict the use of wood stoves and fireplaces during certain periods. Wood burning adds particulates, as well as other pollutants, such as carbon monoxide and formaldehyde, to the air. Combined with other sources, such as transportation and industry/commerce, air quality in the winter months may be worse than other seasons.

According to the 2014 state emissions inventory, the most recent data available to consider, there are approximately 62,000 wood heating devices in Spokane County; residential wood heating is the largest source of fine particle pollution in Spokane County, accounting for 1,116 tons of fine particle pollution annually. This last statistic is notable, as wood heating typically only occurs for less than half of the year.

The amount of wood smoke exposure is a function of how well the wood burns, how quickly the smoke rises and dissipates, and the amount of exposure time, both indoors and outdoors. Well-seasoned wood (moisture content less than 20 percent) burns hotter and better than greener wood. Ensuring there’s sufficient air circulation also makes for a hotter, cleaner fire. Both drafty homes as well as those that are air-tight can lead to increased levels of smoke inside the house, with one study finding a 29 percent increase of fine particles in homes using wood heating.

What can you do to lessen health risks from winter wood burning? Ensure your home is well-weatherized and consider cleaner sources of heat.

If you decide to use wood, however, it should be well-seasoned (at least one year). Keep the fire burning hot by not overcrowding the stove or fireplace to ensure good air circulation. Also, check out the smoke coming from the chimney. If you can see smoke, you’re wasting fuel and the fire needs more air and/or drier wood.

Make sure you’re using an appropriately-sized, EPA-certified wood or pellet stove that’s properly installed. If your wood stove was built prior to 2000 or is not EPA-certified, state grant funds may be available to help replace it. For details, go to the Washington State Department of Ecology’s website: https://ecology.wa.gov/Air-Climate/Air-quality/Smoke-fire/wood-stove-info. If in Spokane County, visit Spokane Regional Clean Air Agency’s website: SpokaneCleanAir.org. These websites are also where you should check for any wood-burning restrictions that may be in place before you light your wood burning stove or fireplace.

While wood fires can be warm and toasty, if they are not your only source of heat, there may be better heating options for your health and those of others.