What does negative pressurization indicate about air movement in a building?

Negative pressurization indicates that more air is leaving a space than is entering it. This situation often occurs when exhaust systems, such as those used for ventilation or fume hoods, remove air at a greater rate than the equivalent amount of air is replaced from outside. As a result, the pressure inside the building becomes lower than the atmospheric pressure outside, which can lead to air being drawn into the building from surrounding areas, including potentially contaminated or unconditioned spaces.

This condition is significant in mold remediation and indoor air quality assessments because when air flows into a building from outside, it can carry moisture and pollutants, contributing to a suitable environment for mold growth. It is crucial for practitioners to understand the implications of negative pressure as it affects how air moves within the space and can influence remediation strategies and overall building health.