How to Ventilate a Room When Painting or Stripping Paint

EPA says that during and for several hours after activities such as paint stripping, indoor levels of some organic chemicals may be 1,000 times background outdoor levels. Opening windows, running exhaust fans that vent outdoors, and doing the work outside when you can are the steps EPA lists. The sections below cover what the fumes are and how to set up a room.

1. What you are ventilating: VOCs

Paints, varnishes, and waxes all contain organic solvents, according to EPA, and those solvents give off gases called volatile organic compounds (VOCs). EPA notes that VOCs are released while a product is in use and, to some degree, while it sits in storage.

EPA's figures on indoor levels:

• Concentrations of many VOCs are consistently higher indoors than outdoors, up to ten times higher.
• EPA's Total Exposure Assessment Methodology (TEAM) studies, completed in 1985, found about a dozen common organic pollutants at 2 to 5 times higher levels inside homes than outside, in rural and highly industrial areas alike.
• During and for several hours immediately after activities such as paint stripping, levels may be 1,000 times background outdoor levels.

That last number is why a stripping project in a closed room feels so different from an ordinary day.

Health effects EPA lists for VOC exposure include eye, nose, and throat irritation, headaches, loss of coordination, and nausea, with some compounds linked to liver, kidney, or nervous system damage at higher exposures. EPA also notes that effects vary widely by chemical, and that not much is known about long-term effects at the levels usually found in homes.

2. Two products that deserve extra care

EPA singles out two ingredients that show up in painting projects:

Methylene chloride, listed on EPA's indoor air page as an ingredient in paint strippers, adhesive removers, and aerosol spray paints. EPA says it is known to cause cancer in animals and is converted to carbon monoxide in the body, so it can cause symptoms associated with carbon monoxide exposure. That page advises using such products outdoors when possible and indoors only if well ventilated. Note that EPA has since prohibited methylene chloride for consumer paint and coating removal: after November 22, 2019, it cannot be manufactured, processed, or distributed for that use, and EPA encourages consumers to stop using products they already own and to ask local solid waste agencies how to dispose of them. Check the label of any stripper or adhesive remover you find.

Benzene, a known human carcinogen. EPA names stored fuels and paint supplies among its main indoor sources and recommends maximum ventilation during painting and discarding paint supplies and special fuels you will not use soon.

Reading the ingredients before you use any stripper is the easiest way to decide whether a project should move outside.

3. How air actually gets in and out

The Inside Story, a joint EPA and Consumer Product Safety Commission guide, says most home heating and cooling systems, including forced air heating systems, do not mechanically bring fresh air into the house.

The guide lists these ways to raise the outdoor ventilation rate:

• Opening windows and doors
• Operating window or attic fans, when the weather permits
• Running a window air conditioner with the vent control open
• Using local bathroom or kitchen fans that exhaust outdoors, which remove contaminants directly from the room where the fan is located

The guide says it is "particularly important" to take as many of these steps as possible during short-term activities that generate high pollutant levels, and names painting, paint stripping, and sanding among them. It adds that you might do some of these activities outdoors if you can and the weather permits.

4. A practical setup for an indoor paint job

The steps below combine EPA's guidance with common setup practice; the fan placement in steps 2 to 4 is a practical arrangement, not an EPA instruction:

1. Open windows on two sides of the room or house if possible, so air has an inlet and an outlet.
2. Put a box fan in one window facing out to pull fumes out of the room, and leave another window open as the air inlet.
3. Run any exhaust fan that vents outdoors in or near the work area.
4. Close the door to the rest of the house if your exhaust setup allows, so fumes go out the window rather than into hallways and bedrooms.
5. Keep ventilating after you stop. EPA says elevated concentrations can persist in the air long after the activity is completed.
6. Follow the label. The Inside Story says that if a label says to use the product in a well-ventilated area, go outdoors or to an area equipped with an exhaust fan; otherwise open windows to provide the maximum amount of outdoor air possible.

5. Buy for the job, not the shelf

EPA's advice: if you use products such as paints and paint strippers only occasionally, buy only as much as you will use right away. It also says not to toss unwanted products in the garbage, and to find out whether your local government or a community group sponsors collection days for toxic household wastes. Because gases can leak even from closed containers, EPA suggests throwing away old or unneeded partly full containers safely, and storing what you keep in a well-ventilated area out of children's reach.

6. Signs the room is not getting enough air

The Inside Story lists signs that a home may not have enough ventilation, including smelly or stuffy air and moisture condensation on windows or walls. Its odor check: step outside for a few minutes, then reenter and note whether odors are noticeable. Applied between coats, a noticeable smell suggests the room needs more air exchange.

7. Key takeaways

• EPA says many VOCs are up to ten times higher indoors, and during and for hours after paint stripping levels may be 1,000 times outdoor background.
• Forced air heating and cooling systems do not mechanically bring fresh air into the house.
• Use cross-ventilation with a window fan blowing out, plus outdoor-vented exhaust fans, during and after the job.
• EPA prohibited methylene chloride for consumer paint removal after November 22, 2019; check labels on older products and follow EPA's outdoor-use advice.
• Buy only what you will use right away, and ask your local government about household hazardous waste collection for leftovers.