Don’t store the lawnmower in your house! (You could be without knowing it)

This sounds like crazy advice, but give me a minute…your home has a building “envelope” that keeps the outdoor air and water outside and your conditioned air inside.  In older homes with attached garages, this envelope is often extended to include the garage, even though it’s unconditioned, because the builder did not apply an air barrier between the garage and home.  If your attached garage is not air-sealed from your home, VOCs from the garage can easily pass into your home under the bottom of the drywall (if it’s a finished garage), through cracks around the door, through electrical sockets, and through light and garage-door opener fixtures in the ceiling.   AND, not only does the mower (and YOUR CAR) emit gases like carbon monoxide (CO), unburned hydrocarbons (HC) and oxides of nitrogen (NOx) when they’re running (Exhaust Gases 101), they can emit a lot of VOCs just when parked, because gasoline evaporates from their fuel systems.  Gas-powered lawn equipment will leak more of these, because they are not as efficient as car engines, and typically, people also store gas containers nearby as well.  Typical gasoline contains about 150 different chemicals, including benzene, toluene, ethylbenzene and xylene.  Gasoline also contains chemicals such as lubricants, anti-rust agents and anti-icing agents that are added to improve engine performance.  Some gasolines also contain ethanol, which is made from corn, helping a car run more efficiently. The most common additive used in gasoline is methyl tertiary-butyl ether (MTBE). It is added to increase octane and oxygen levels and reduce pollution emissions. (Gasoline Fact Sheet)  All of these can be emitted in several ways even when the engine is not running (Can cars create air pollution even when they are parked?): 

• Diurnal – Gasoline evaporation increases when the temperature rises and the fuel tank is heated up.

• Sitting Evaporation – the engine remains hot a certain period of time after it is turned off and gasoline evaporation continues even when the machine is parked.

• Adding Fuel – Gasoline vapors are always present in fuel tanks. These vapors are forced out when the tank is filled with liquid fuel, so it’s best to refuel small gasoline engines outside the garage.

These chemicals and VOCs are not good!  You may have the experience of breathing the air at the gasoline station while refueling, causing you respiratory irritation, headaches or nausea.  However, when even small quantities of hydrocarbons enter the bloodstream, it can reduce the functioning of the central nervous system (CNS) and cause organ damage. (How does gasoline exposure affect a person's health?)  We also just found out that a very poisonous gas, ethylene oxide, is emitted from lawn mowers at 41,000 times the EPA’s safe limit.  If your house is under negative pressure, such as when you run the dryer, kitchen or bathroom exhaust vents, it can pull these vapors from the unsealed garage right into your home.

If you have very little outdoor space and want to continue to use your garage as your main storage spot, we get it.  We wrote an article on sealing your attached garage.  It does take a bit of work, but thankfully products like spray foam in a can make it a lot easier!   If part of your living space is over your garage, and there’s a large temperature differential in the winter or summer, special care should be taken to make sure the air barrier is correctly placed to ensure condensation and mold do not develop. 

If you have just a bit of space on the edge of your yard, consider getting a small storage shed.  This 3x5 ft Outdoor Storage Shed at $111 (assembly required), should be big enough if you just have a small push mower, weedwacker and gas cans.  It’s a great investment for keeping these fumes away from the home.  It doesn’t come with shelving, but these could be installed to hold any paint cans, pesticides or fertilizers that really shouldn’t be stored in your unsealed garage, either.   Think about your bathroom wall and door, which are often not enough to contain the “odors” of the bathroom.  Just because the door from the home to the garage is closed, it does not mean that the chemicals in the garage are going to stay there.  Sometimes it takes extra (but worthwhile) effort to move the home’s envelope to where it should be–just around your living space.

Photo by Michael Kahn on Unsplash