Which of the following is a consequence of inadequate ventilation in a building?

Inadequate ventilation in a building directly leads to an increased concentration of indoor pollutants. When ventilation is insufficient, the air exchange between the inside and outside is limited, causing contaminants such as volatile organic compounds (VOCs), carbon dioxide, dust, and biological agents (like mold and bacteria) to accumulate. This accumulation can result in various health issues for occupants, including respiratory problems, headaches, and fatigue, as well as decreased overall air quality.

The other options highlight scenarios that do not result from poor ventilation. Improved occupant productivity usually requires a healthy indoor environment with adequate airflow and air quality, which is contrary to the effects of inadequate ventilation. Lower humidity levels are typically associated with good ventilation, as proper airflow helps manage moisture levels in a building. Effective control of outdoor allergens also depends on proper ventilation systems that filter and manage outdoor air, rather than inadequate ventilation that can allow allergens to accumulate indoors. Thus, the consequence of increased concentration of indoor pollutants accurately reflects the dangers associated with inadequate ventilation.