It's a car, it's a cyclist, it's a mobile wireless sensor

The next time you see a pedestrian or cyclist crossing the road, you might also be looking at a mobile wireless sensor monitoring urban air quality.

Scientists at Imperial College London this week launched a study that equipped pedestrians, cyclists, buses and cars with mobile wireless sensors as part of a demonstration of new ways of measuring air quality.

The study aims to show transport authority and industry representatives how small mobile sensors could improve how air quality in urban areas is monitored and managed.

“There is a lot that we do not know about air quality in our cities and towns because the current generation of large stationary sensors don’t provide enough information,” said project director John Polak, from the college’s Centre for Transport Studies. “We envisage a future where hundreds and thousands of mobile sensors are deployed across the country, to improve the way we monitor, measure and manage pollution in our urban areas.”

Scientists deployed three new types of sensors in this week’s demonstration, measuring multiple types of traffic emissions and noise pollution. The team received data from 100 sensors deployed in South Kensington, Leicester, Gateshead and Cambridge to test how they operate from different locations.

The new sensor technology means researchers can now measure and model air quality in unprecedented detail to improve their understanding about pollution hot spots and analyse the factors such as bad urban design that contribute to poor air quality. The scientists will also model pollution clouds in 3-D, by attaching sensors to traffic lights and street lamps. They aim to understand how pollution forms, lingers and dissipates in high emission zones.

The researchers hope this will lead to insights about whether, for example, poor signalling is causing traffic congestion which contributes to reduced air quality in the area.

The scientists will deploy sensors that will measure up to five traffic pollutants simultaneously including nitrogen oxides and sulphur dioxides. Researchers have equipped the sensors with ultraviolet absorption spectroscopy technology, which uses ultraviolet light to detect pollutants in the atmosphere. This means researchers can take air quality measurements at five-second intervals, which is fast enough to allow deployment on moving cars and buses. These sensors were attached to vehicles driving around South Kensington.

Another type of sensor was attached to pedestrians and cyclists to measure the pollution they were exposed to as they moved around. These sensors are small enough to fit into a pocket and can detect car pollutants and other contaminants including carbon monoxide from cigarette smoke. The sensors utilise the wearer’s mobile phone to transmit data which enables the wearer to monitor pollution levels around them.

In addition, the team installed sensors to analyse the link between traffic congestion and levels of pollution in targeted locations such as pedestrian crossings, traffic intersections, industrial areas and motorways. These sensors measure noise and air pollutants and use ultrasound technology, where high frequency sound is bounced off cars, to count traffic driving past. They are located at South Kensington, Gateshead and Leicester.

The air quality measurements and the location of each mobile sensor will be tracked on Google maps.

The Mobile Environmental Sensing System Across Grid Environments (MESSAGE) initiative is led by Imperial College London and brings together international specialist research groups in the fields of e-science, transport, sensors and communications technologies from the Universities of Cambridge, Leeds, Newcastle and Southampton.

The three-year project is jointly funded by the Engineering and Physical Sciences Research Council and the Department for Transport.