Poor indoor air quality is considered unhealthy because it causes tiredness, loss of ability to concentrate and even illness (e.g. Sick Building Syndrome). Indoor Air Quality (IAQ) monitoring, especially on CO2 levels and air ventilation, is becoming widely applied in public areas such as offices, classrooms, factories, hospitals and hotels. It is also suggested in regulations of industrial hygiene in some countries. This portable CO2 meter uses NDIR (Non-Dispersive InfraRed) technology to ensure reliability and long term stability. It has an onboard datalogger to store readings for later analysis. The Vent Check Pro detects carbon dioxide, carbon monoxide and temperature. The handheld unit also shows Time Weighted Average and Short-Term Exposure Limit.