 Tunnels are crucial road infrastructure, especially in mountainous regions. They save a lot of time and fuel and provide reliable rail and road transportation in all seasons. More and more underground parking facilities are being constructed to accommodate ever-increasing vehicular congestion. However, the environment inside a tunnel or underground parking lot is very different from an ambient environment. In an enclosed space such as a tunnel or underground parking lot, free flow of fresh air is absent. Air pollutants emitted due to vehicular activities are not diluted by fresh ambient air. They accumulate in the tunnel or underground facilities over the period of time. In such an environment, exposure to pollution is unusually high. Sometimes during high vehicular traffic, pollutants trapped in inside tunnels may also cause visibility issues. That increases accident hazards. The solution to all these problems is an adequate and efficient ventilation system. But for these systems to work efficiently, we must have a clear idea about the concentration of air pollutant present in the tunnel or parking lot. As vehicular emission is the only source of pollution, the usual pollutants of interest in tunnels and parking lots are nitric oxide, nitrogen dioxide, carbon monoxide, particulate matter and visibility. Monitoring air quality in real time helps us in designing the most effective protocol for activation of ventilation systems. This saves significant operating costs. Also, such an optimized system ensures that adequate ventilation is available all the time. Air quality monitoring and efficient ventilation management significantly reduce exposure and also reduces accident hazards. To read in detail about how effective the solution is, click on the link in the description below.