Air quality monitoring | Tunnels | Parking Lots | Air particulate monitoring | Dust monitoring
Channel: Oizom
Date: 2020-09-18

https://oizom.com/roadside-pollution-monitoring/

The environment inside any enclosed underground infrastructure be it a tunnel or underground parking lot, is very different from an ambient environment. In an enclosed space, the free flow of fresh air is absent. As a result, the air inside them is almost stagnant. Air pollutants emitted due to vehicular activities are not diluted by fresh ambient air. As they have nowhere to escape, they accumulate in the tunnel or underground facilities over the period of time. Such accumulation of harmful air pollutants causes many problems, including health complications and increased road-accident hazards. 

An environment where inside polluted air is not exchanged with fresh air causes serious health issues. Exposure to pollution is unusually high in such a condition. Even if we are in our vehicles while passing through a tunnel, our exposure to pollutants is significantly high if tunnels are poorly ventilated. Such hazards are especially serious for parking lots, because unlike tunnels, people spend a considerable amount of time outside their vehicles. However, exposure risk is disproportionately high to workers employed to work in parking lots and tunnels. 

Another very serious issue of poor ventilation of polluted air is road-traffic accidents. Sometimes during high vehicular traffic, pollutants trapped inside tunnels may also cause visibility issues. That increases accident hazards. Serious accidents might lead to hours of traffic jams and temporary tunnel closures. As a result, lots of time, fuel and other resources get wasted. 

The fundamental reason for all these problems mentioned above is the lack of ventilation in enclosed and underground infrastructure. If adequate and efficient ventilation is provided, these problems can be easily solved. There are many ways of providing ventilation in tunnels and parking lots. Some techniques and designs facilitate natural ventilation, while many mechanical options are also available to aid natural ventilation. Majority of modern ventilation systems work on a mix of both of them (hybrid systems), which is partially natural ventilation and on top of that mechanically aided ventilation. Such systems save operation costs when they operate efficiently.

But for these systems to work efficiently, we must have a clear idea about the concentration of air pollutants present in the tunnel or parking lot. This is where air pollution monitoring of tunnels and parking lots comes into picture. A clear understanding of the presence of air pollutants, its extent, concentration and trend helps in fine tuning and optimizing our ventilation systems. 

Air pollution monitoring data provides us with information such as, what is the extent of pollution, what is the pollutant concentration, which pollutant is predominantly high, etc. With the help of this dataset, the ventilation system can be fine-tuned so that adequate ventilation can be maintained all the time. By integrating real-time air quality monitoring data with ventilation systems, high ventilation efficiency can be achieved. This ensures that enclosed spaces such as tunnels and parking lots are adequately ventilated all the time, even during high vehicular traffic.  

Measuring representative air quality in enclosed underground spaces is also a difficult task. As vehicular emission is the only source of pollution, the usual pollutants of interest in tunnels and parking lots are, NO, NO2, CO, particulate matter (PM) and visibility. Various factors that affect air quality monitoring are turbulence, generation of piston effect due to vehicular movement, type of ventilation system, road design etc. Also, air pollutant concentration in the tunnel and parking lots vary significantly along with length and depth. In order to get representative concentration, air quality monitoring is carried out in the ventilation stacks, as well as at the ground locations. Sites with minimum interference from turbulence are selected for monitoring. Read Oizom’s Whitepaper on monitoring location selection for detailed monitoring guidelines and to understand how to carry out monitoring in tunnels and parking lots to ensure that highest quality data is recorded. 

AIR POLLUTION MONITORING IN A TUNNEL
Oizom’s Polludrone was stationed at a crucial tunnel connecting Jeddah with the holy city Mecca in Saudi Arabia. Due to high vehicular activity during the holy month of Ramadan, the tunnel faces excessive air pollution. A network of Polludrone was deployed throughout the length of the tunnel to identify peak pollution hours and provide data-driven solutions. The real-time air pollution monitoring data provided with actionable insights and helped in optimizing the tunnel ventilation systems. Significant pollution reduction was made possible by integrating real-time monitoring data from Polludrone to ventilation fans. This ensured safe air quality throughout the tunnel length all the time.