You may find yourself asking “if no one in my household smokes, why can I smell secondhand smoke inside my apartment?”. The CDC has determined that there is no safe level of secondhand smoke, and over 2 million nonsmokers have died in the US since 1964 from health problems related to secondhand smoke[note]U.S. Department of Health and Human Services. The Health Consequences of Smoking—50 Years of Progress: A Report of the Surgeon General. Atlanta: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2014[/note]. The best way to avoid secondhand smoke is to keep your home smoke free, but what do you do when your neighbor smokes like a chimney? There are a few different ways that odors from secondhand smoke, technically called environmental tobacco smoke (ETS), can enter into a neighboring unit. Finding out what is specifically happening in your situation may be a bit of a challenge.
Pathways for Secondhand Smoke
When we do inspections for this kind of concern, we always check for the most common pathways first. The most common pathways are wall openings along a shared wall. This could be an electrical outlet, light switch, plumbing opening under sinks or for laundry hook-ups, or any other opening in the wall. Another common issue may come from shared exhaust ductwork. Ideally, there is a damper that closes when the exhaust is not in use to prevent any air infiltrating from the connected spaces, but this is not always the case. Occasionally there may even be a gap where the wall and flooring meet which allows for air to move from one unit to another very easily.
Openings in walls are only part of the story. An equally as important issue to understand how secondhand smoke can enter a neighboring unit is pressurization. In buildings, pressurization is a major factor in how air moves from one space to another. Without getting too into the weeds, it is important to know that air will move from an area of high pressure into an area of low pressure. Some things that can create a negative pressure in a space are bathroom/kitchen exhaust fans, a clothes dryer, or a furnace. There are some building dynamics which will affect pressurization such as stack effect. This is the movement from the air in lower levels to higher levels. Therefore, if the smoker is in the unit below you, the secondhand smoke will usually move up into your unit easier than it could move down into a lower unit.
Sealing up physical pathways into your unit can be done for example using spray foam. Having a smaller opening, or possibly sealing off openings completely can significantly reduce the amount of secondhand smoke entering into a neighboring unit. Addressing pressurization in a building can be more difficult. Increasing pressure in your unit could be done by adding an outdoor air intake to the HVAC system. In a rental, this would require having a very cooperative landlord!
Of course, these are only a few examples of situations we can see related to secondhand smoke. In fact, these issues can be some of the most complex issues we work on as indoor environmental professionals. Each year fewer and fewer people in the US smoke, so hopefully in the future, we will see less conflict over this issue.