You’ve been told to go home. And stay there. When faced with a pandemic against which we have no immunity, being in small groups at home is safer than being in crowds. Now that you’re at home for a while, there are things you can do to make that environment even safer, too.

Idea #1: Increase your ventilation rate

Start by increasing ventilation to get contaminants out of the home. When people are at home all day, they naturally generate more contaminants like moisture or fumes from cooking and cleaning. 

• Turn on exhaust fans, especially the range hood. This measure works only if the fans actually exhaust to the outdoors. Check whether each fan has a duct, and whether that duct goes outdoors. Outlet vents on the roof or through the wall show where exhaust air leaves the home.
• Run ventilation systems that are connected to the furnace continuously when there are contaminants of concern in the home, even when not heating or air-conditioning. Not all homes have this type of system. If yours does, it will likely have a control at the furnace.
• Run heat recovery ventilators (HRVs) all the time. During periods when you want more ventilation, put the HRV on the highest flow option.
• Communicate with your neighbors about ventilation in multi-family buildings. Increasing exhaust ventilation only in your unit might bring your neighbors’ air into your space. However, if everyone turns their fans on, the building as a whole becomes better ventilated.
  • If the building management controls a central shaft exhaust, individual apartment dwellers don’t control the ventilation. Management may be able to turn the central fan to a higher setting.

Idea #2: Create a separated zone in your home

If a person in your home is ill, there are ways you can reduce the air connection between their space—we’ll call it the “separated zone”— and the rest of the home. The goal is to decrease the pressure in that space compared to the rest of the home, and then vent the separated zone to outside. This idea is based on the simple principle that air flows from high pressure to low pressure. Here are some steps:

• Turn on any exhaust fans in the separated zone. This will lower the pressure in that zone.
• Add more exhaust ventilation to the room. Standard exhaust fans are often not enough, so you can mount a box fan in the window, blowing outward, and seal the rest of the window opening with plastic or cardboard.
• Do NOT increase exhaust ventilation, like bathroom and kitchen fans, in other parts of the home (except when you are cooking or bathing). That ventilation reduces pressure in the rest of the home, and air from the separated zone might travel back to the home.
• Close off central-air system supply registers and return grilles in the separated zone, so that air from that zone is not distributed through the whole house. Use tape, or tape plastic over the registers and grilles, in addition to closing the louvers.
  • You may need to consider alternative sources of heat or air conditioning for the separated zone. If you use portable space heaters, be careful to use only models that shut off if they tip over, and keep all flammable materials away from them.
  • If you do NOT have a central-air system, you don’t have to do anything else. For example, heating from a central boiler is fine to condition the separated zone.

You also need to make sure anyone in the separated zone can get to the bathroom, and have other needs met. A master bedroom with connected bathroom may be the best choice for a separated zone since it provides toilet and water and usually contains an exhaust fan.

Creating a separated zone, marked by bold borders. Red arrows show air pushed to outdoors, controlled by fans. The large fan in the window exhausts from the separated zone to outside. Bathroom and any other exhaust fans in the zone should be on. Green arrows show how air will move from the rest of the home into the separated zone, drawn in by the low pressure in the zone.

NOTE: Air from the remainder of the home is likely to travel into the separated zone. If others in the home have been exposed, and you want to isolate a sensitive person from the remainder of the home, you CANNOT put the sensitive person in a separated zone created in this way.

Idea #3: Plan for future health in your home

As you pay attention to airflow and contaminants, you might notice some aspects of your home that you can address when time and resources are available.

Make sure your fans are working well. Take a single piece of toilet paper and hold it up to the fan. (We know toilet paper is precious these days, but you can spare one piece!) If the fan cannot hold the toilet paper to its grille, then it is not moving much air. Do the fans vent to the outdoors? Fans that are noisy often don’t move much air. Quiet fans may be more expensive, but also work better and last longer.

If you have big air leaks, seal them – it will make your home’s air easier to control with fans. Managing a leaky home is like drinking through a straw with a hole in the side. You really have to work to move the fluid in the right direction.

Take the opportunity of being stuck inside to look around your home. Other organizations (not affiliated with SPHERE) provide many resources to learn more about Healthy Homes:

Paul Francisco is a researcher and trainer at Indoor Climate Research and Training (University of Illinois) and Energy Institute (Colorado State University).  He teaches Healthy Homes to practitioners, is a former chair of ASHRAE’s Residential Ventilation Standard (62.2) and Environmental Health Committees, and is the current chair of ASHRAE’s Residential Buildings Committee.