Air quality is a vital component in our lives. Yet it is very hard to feel or sense, since its changes are usually gradual. We are all familiar with that situation when one person enters the room we’ve spent the past couple of hours in and immediately says: “The air is really bad”. Usually, we don’t notice the air quality degrade while we are in the room. Therefore it seems logical to transfer this task to a technological device.

Indoor air quality has a significant impact on public health. Nowadays, an average person spends approximately 90% of their time indoors. The US-American Environmental Protection Agency identified poor indoor air quality as one of the five major public health risks.

At workplaces the air quality is sometimes measured, but this is usually a single measurement.

Continuous indoor air quality measuring provides immediate feedback relevant to that current situation.

Most IAQ systems that are commercially available are designed to warn users once the measured data passes a certain dangerous limits (for example smoke detectors). However, they don't deliver regular data.

Our goal is to create a wireless indoor air quality monitoring system that measures carbon monoxide (CO), carbon dioxide (CO2), VOC (volatile organic compounds) and temperature within our university buildings and communicate the data to the students and staff using those buildings.

This will raise the user's awareness of air quality and possibly trigger actions like opening windows or going outside to take a break and get some fresh air.

Volatile organic compounds (VOCs) are gases that get emitted by certain liquids or solids. Some VOCs can lead to adverse health effects. Monitoring VOCs is especially relevant indoors because the concentrations of VOCs are higher indoors than outdoors (up to 10 times). On top of that, VOC pollution persists long after the actual usage moment of the VOC-emitting product. Sources of VOCs are paints, cleaning products, air fresheners, wood preservatives, etc. Short term health effects are irritation of eye, nose and throat, headaches, nausea, and coordination problems. On the long term, exposure to VOCs can damage liver, kidney and the central nervous system and some VOCs are known to cause cancer.

Carbon monoxide is often referred to as the “silent killer” because it reduces oxygen delivery to the body’s organs and tissues and can cause death. The fact that it is odourless and invisible makes it especially necessary to monitor. Indoor monitoring is essential because CO levels can quickly become lethal in closed environments. Causes include malfunctioning fuel-burning devices such as water heaters or furnaces, fireplaces, generators or other engine-powered devices, etc.

The main source of indoor carbon dioxide emissions are humans. High levels may lead to drowsiness or headaches.

But why a wireless sensor network?

The divided spaces of large buildings exhibit vastly different microclimate conditions, which necessitate simultaneous distributed monitoring with many sensor nodes to accurately characterize the spatiotemporal dynamics and correlation properties of the air quality conditions throughout the building.