Smoke? Pollution? How to keep your indoor air clean

Can indoor plants improve air quality?

Houseplants are lovely to have around. They liven up a room and can be fun to care for. There’s no shortage of reasons to fill your space with plants. But cleaning indoor air isn’t one of them.

Thanks in part to a NASA study in the 1980s, people started touting various plants for their abilities to cleanse the air of everything from “volatile organic compounds” to ozone to dust and spores. But that study examined the effects of plants in closed environments, without the leaks, windows and doors of a home. More recent research has found that even an abundant houseplant jungle has little effect on indoor air quality.

So, as we face more wildfires from global heating and pollution as traffic starts up, how do we improve air quality in our homes?

Easy ways to improve indoor air quality

Plentiful fresh air is essential for good health. But when air quality plummets because of pollution or smoke from wildfires, closing windows, doors and vents is best. Here are a few temporary measures that have been shown to help with smoky air from wildfires.

Below are three solutions, each using a high-end, ultra-allergen furnace filter (e.g., 3M’s Filtrete, with filtration level of 1900, 2200 or 2800, or other brand of filter with MERV rating of 13 or up).

If you have a forced-air furnace/heat pump system or central HVAC system:

  1. Replace the filter with a new, high-quality, ultra-allergen filter. Ensure the filter is compatible with your unit, and install it so air flow is as shown on the filter.
  2. Set the fan to operate continuously. (Your furnace or thermostat usually has a manual setting for continuous fan operation.) Confirm that air is flowing to the vents.
  3. The advantage of this approach is that it will filter air in several rooms of the house.

If you have a box fan:

  1. Find a high-end filter the same size as your fan.
  2. Tape the two together, making sure you get the direction of the filter correct. (Arrows show which way the air should be pushed through the filter.)
  3. This video shows how.

If you have a standard fan:

  1. Cut a circular opening matching the fan’s size in one end of a box and either cut an opening or open the flaps at the opposite end. Attach the fan such that the box will be pressurized.
  2. Put the high-end filter on the other end and tape.
  3. Turn on and check that air current is getting through. (The filter slows it so you likely need to run it on high or medium.)
  4. Make sure there is no possibility of the fan overheating.

Keep in mind that fans use energy, so don’t run them when they aren’t necessary.

Of course, if your area is frequently exposed to smoke, you may wish to purchase a dedicated HEPA air purifier. These vary in effectiveness, so check independent ratings and avoid units that generate ozone, since this can cause dangerous indoor air quality. Note that many of these units are only sufficient to improve air quality in one room.

Homes built to exacting energy-efficiency standards such as PassivHaus use equipment such as HRV or ERVs for ventilation and heat recovery. Because these homes are airtight, it is essential that this equipment, which typically incorporates excellent air filtration, is operated according to specifications to ensure sufficient air exchange.

More things you can do to reduce indoor air pollution

  1. Reduce what you track into your house, and dust surfaces often.
  2. Avoid toxic chemicals.
  3. If possible, choose products that don’t off-gas, such as eco-friendly mattresses and pillows.

And, of course, remember that the best way to keep indoor air clean is to clean the outdoor air. Doing all we can to address carbon emissions that cause global heating will also reduce pollution and the number and intensity of wildfires.

Cleaner air and a stable climate make healthier homes. Houseplants make them even nicer!