Which practice is a recommended control to improve indoor air quality in offices and labs?

• A. Improve filtration
• B. Increase humidity to excessive levels
• C. Seal ventilation
• D. Use air fresheners

Answer: (A)

Improving filtration reduces the amount of airborne particles and many contaminants reaching people by trapping them in the HVAC filter as air circulates. In offices and labs, using filters with high efficiency (such as MERV 13 or higher, or HEPA in critical areas) and keeping them clean ensures better removal of dust, pollen, smoke, and finer particles, which lowers exposure for occupants. Proper installation matters too—gaskets seal properly and filters are replaced on schedule so the filter bed remains effective. Filtration works well as part of a broader control strategy that also includes adequate ventilation and source control, but it avoids introducing moisture problems or additional emissions. For example, increasing humidity to excessive levels can promote mold growth and dust mites; sealing ventilation reduces beneficial outdoor air exchange; and air fresheners release VOCs that can irritate airways. So improving filtration directly reduces contaminants without those trade-offs.