This article explores four common IAQ “comfort” complaint scenarios that could be more than just comfort: Scenario 1: A Receiving Desk clerk working in a warehouse reception area complains, “I sometimes smell truck exhaust odors, and I hate that smell.” Is this only a comfort issue, or is it something potentially health related, like potential exposure to VOCs or carbon monoxide?  Scenario 2: An office worker complains about being “too warm” sitting at his desk in a small office, where conditions obviously don’t come close to exceeding the ACGIH wet-bulb globe temperature values provided for the control of heat stress.  Scenario 3: A university instructor complains she feels a strong air draft when she stands at a podium in front of the class because the air supply register on the wall is blowing air on her. But there are no specific limits set for the maximum average air velocity passing a teacher in a school.  Scenario 4: A slight majority (55 percent) of those in an office suite in Denver complain that it’s “too humid in here.” Before we jump into these scenarios, we should also consider what’s average or typical for the conditions we are going to investigate. For example, what range of concentrations of carbon monoxide would we normally expect in a warehouse reception area? That varies from place to place, but it wouldn’t be highly unusual to see average CO levels of 0.5 to 5 ppm in an indoor environment. Carbon monoxide in the exhaled breath of non-smokers can average as high as 5–10 ppm, so occupants themselves can sometimes be the source of low background levels of CO indoors in occupancies with poor ventilation. (This is another reason to be sure that we are supplying recommended amounts of outdoor air to occupied spaces.) SCENARIO 1 We follow up with our warehouse desk clerk and find that she is indeed exposed to truck exhaust containing carbon monoxide at indoor concentrations averaging about 10 to 15 ppm, which is well below the ACGIH time-weighted average TLV of 25 ppm. Searching the literature, we find IAQ guidelines that identify 5 to 10 ppm as suggested upper limits for indoor concentrations of CO. The desk clerk also says she sometimes feels a little “headachy,” which suggests there are times when the exposure levels may exceed our measurements. We discover that the fresh air intake for the receiving area ventilation system is located next to the warehouse loading dock.  What are our options? We would likely recommend that trucks not be allowed to run while at the loading dock and that the air intake should be moved farther away to reduce indoor CO to background levels. SCENARIO 2 For the office worker who complains of being too warm, we should first note the season. Let’s say it’s summer. A quick temperature measurement shows that the air in the occupied small office is about 78 degrees Fahrenheit and also a few degrees above the air temperature in offices located nearby. The worker says that he sometimes feels increased irritability, has problems fully concentrating on his work, and takes more time to get his work finished (all of which can be related to environments that are too warm). We note that the office worker is fully dressed, including a suit coat and tie. What could we do? ASHRAE studies suggest that 80 to 90 percent of non-physically active people prefer temperatures between 68F and 76F, the cooler temperatures in winter when they’re dressed for cold weather and the higher temperatures in summer when they’re dressed for warm weather. We explore several options. First, we could suggest the person dress more for the season (no suit coat, maybe a short-sleeve shirt). Second, we could supply a small, quiet fan that the person could direct toward himself to provide some cooling air over his body, help move away the body’s warmer air, and improve cooling evaporation on his skin. Third, we could check with the other occupants of the ventilation zone and see if they would tolerate a lower temperature and then lower the thermostat a degree or two. Fourth, we could try to determine why our complainer’s office is warmer than adjacent offices. Does the ventilation to his office need to be adjusted? Does the office get more sunlight than others? Is there a heat source in the office, like hot computer screens?  SCENARIO 3 How about the teacher who says her classroom is too drafty? ASHRAE and other studies have found that we feel air movement on our hands and arms at a velocity of about 100 feet per minute. Many can feel air movement at 50 fpm on their necks and ankles. (That’s one reason why we wear shirt collars and socks that cover our necks and ankles.) These studies also suggest that most people like to have air velocities of about 30 to 50 fpm around them, or they may feel it is “too stuffy.” People also tend to dislike velocities above the range of 100 to 150 fpm, which some describe as “drafty.”  Knowing this, we measure the air velocity at the teacher’s podium, finding it ranges from 160 to 200 fpm at the level of her head and 70 to 90 fpm near her ankles. She also complains of dry skin and rashes. This last finding suggests we should quickly provide some relief—for example, by adjusting the inlet air supply register so it blows up and over, or behind, the teacher. We could also provide a screen near the teacher. For a longer-term solution, we should have the vent system checked to be sure it is balanced appropriately. SCENARIO 4 Let’s finish with the humidity complaints from occupants of the Denver office suite. Since the complaints are coming from more than half of the occupants, the humidity in the space is likely over 60 percent. (ASHRAE and other studies have suggested that relative humidity of between 40 and 60 percent in air are well-tolerated by 80 to 90 percent of occupants.) A quick check using a clear glass filled with water and ice shows water condensation on the outside of the glass after about five minutes, suggesting that the humidity is likely too high. We next measure the humidity with our psychrometer or hygrometer, which shows the relative humidity level is 70 to 75 percent. This level of humidity, besides being uncomfortable, can enhance the potential for mold growth (a health issue), so something should be done to lower the humidity—for example, we could check the operation of the humidifier or dehumidifier in the ventilation system.  THE BEST APPROACH The best approach to any unusual IAQ condition that is causing comfort or health issues is to restore that condition to what is “typical” (or better) of problem-free spaces. Comfort complaints often help us identify real and potential health issues and improve employees’ well-being and productivity, so don’t ignore them. Think of them as opportunities to protect and enhance occupants’ well-being. That’s IH.