It's almost impossible to talk about acceptable indoor air quality (IAQ) in spaces where smoking is allowed, said Larry Schoen, P.E., of Schoen Engineering, Columbia, Md. "Acceptable IAQ means the absence of a negative health effect," he said.

It is something an HVAC professional shouldn't promise to deliver when it comes to smoking establishments, he said. Even second-hand tobacco smoke is considered a Class 1 carcinogen.

Schoen said he limits himself to talking about comfort, not health, in relation to these spaces - bars, restaurants, casinos, any facility or room where smoking is allowed. Moreover, his concept of comfort is expanded from the definition people tend to think about, which includes temperature and humidity. His idea of comfort includes odor. That's the aspect of tobacco smoke he will address.

"Focus on the comfort," he advised.

Schoen listed his top criteria for helping improve the comfort of a smoking space.

Critical Performance

  • When it comes to HVAC system performance and odor control for tobacco smoke, the most critical point of operation, he said, is to run the system continuously. "Don't let it cycle off when the thermal load is satisfied. Run it with lots of outside air.

    "If the system was designed well, it has that built into it." It could also be operated manually during periods of low-smoking activity.

    This continual fan operation "helps everybody's comfort, or people who are not inside the smoking space." Again, this concept of comfort is "not just temperature and humidity, but also odor, irritation, and even visual haze."

    "There is a transference among the senses," he pointed out. A haze of tobacco smoke could make occupants feel worse about the environment than its conditions actually merit.

  • Use high-efficiency filters and change them often. "Use the highest-MERV filter possible.

    "I would be aggressive on the filtration and about sealing up leakage around the surface edges." He advised applying weatherstripping around edges to reduce leakage in cases where a tight seal cannot be achieved with just the filter.

    What about the system's pressure drop? "Manufacturers are making a lot of filters that can fit a large surface area in a small package, with a reasonable pressure drop," Schoen said. "With most air handlers, there are also a few tenths of an inch to install higher-efficiency filtration."

  • Check overall cleanliness, not only of the system but also of the space. Using fewer porous surfaces (such as carpet and duct lining) and more stainless steel, tile, and metal board surfaces that can be cleaned, can go a long way toward maintaining a facility's comfort.

    Mixed-Use Buildings

    Most of us have been in buildings that do not allow smoking except in the restaurant, or in a smoking lounge. Service-maintenance work for mixed-use buildings should be performed to ensure that air is flowing from the nonsmoking area to the smoking area, not the other way around.

    "You have to understand the pressure and flow relationships that are supposed to be maintained," Schoen said. "The flow must go from the clean to the dirty. If it's a cooking facility, look at how it's laid out in relationship to the kitchen."

    Some newer buildings may have separate ventilation for the smoking space, but even then there are generally doors, Schoen pointed out. "It is necessary to maintain pressure and flow relationships in most typical relationships. Understand the design intent and verify that it was done properly."

    Fans and dampers need to be inspected periodically to ensure they are working as designed. Periodic air balancing, or system recommissioning ought to be looked at to ensure that the system is operating as it needs to. "If an ordinary system needs recommissioning every five years, these mixed facilities might need it every year or two. A skilled operator might also pick up on potential problems more often."

    Working Together

    How can system designers and service contractors work together to promote acceptable comfort in smoking establishments?

    "I think everybody can work together by providing lots of ventilation air and nonporous, cleanable surfaces," Schoen said.

    "Make sure the system concept is clear from the designer, make sure its operation is clear for the relationship between smoking and nonsmoking areas, and think about where supply and exhaust diffusers are. The supply could be in a place where less smoking is likely to take place, such as behind the bar if the bartenders don't smoke."

    Contractors can use their knowledge of diffuser placement if the owner proposes a redesign of the spaces interior. Designers can also include cleaning and filtration recommendations in their documentation. It may be up to the contractor to make sure these criteria are carried out.

    "Cleaning of the space can be really good," Schoen re-emphasized; "frequent cleaning using damp, not wet, methods. You can also get the smokers to stay in certain areas, where the exhaust is, and not to stray into other areas."

    Odor comfort is critical for the health and well-being of employees in these establishments, he stated. "Why should employees in a bar have less protection than employees in an office building, or in an airplane? There have been instances of casino workers taking legal action. For my clients, when I go in I make it clear, I'm not touching the health effects. I'm working on odor and irritation. That's what I call comfort."

    Larry Schoen is the chairman of "IAQ 2007 Healthy and Sustainable Buildings," to be held Oct. 15-17, 2007, at Baltimore's Inner Harbor, Baltimore. For more information, visit

    Publication date: 10/03/2005