The growth of urban air pollution is one of the most serious indicators of the impact of global urbanization on the environment and human health. Rapid urbanization, along with associated economic and population growth, has led to increases in vehicle use, industrial activity and energy consumption that have raised urban air pollution to critical levels. According to the World Health Organization (WHO), in 2012 about 3 million premature deaths were attributed to outdoor air pollution exposure. While much of this is happening in the developing world, it is a global phenomenon. As of 2014, about 92% of the world’s population was living in places where air quality levels exceed WHO limits.
If city officials are to fully understand and improve air quality monitoring and management conditions, pollutants must be accurately measured, monitored and managed. Air pollution data is becoming increasingly accessible and localized through the arrival of low-cost sensor networks and crowdsourced projects. Additionally, a wide variety of technologies and policies are being deployed to help manage air quality in cities.
The rise of low cost sensor networks
Currently, most cities measure air pollution using a collection of large environmental monitoring stations. While these stations are very accurate in measuring air quality data, their high costs (anywhere from $10,000 to $25,000 per station) can limit the number of deployments and their static nature can result in the omission of local air pollution problems. Recent advances in sensor and communications technology has led to air quality monitoring solutions that are far smaller in size, less expensive and more localized. Due to these advantages, the use of lower cost sensor nodes ($200 to $3,000 per sensor) with wireless communication systems is one the rise, filling in the gaps left by legacy environmental monitoring stations.
Sensor networks are currently taking the form of a supplement to traditional measurement stations. For example, the air quality Internet of Things network being deployed in Helsinki, Finland is being installed alongside existing air pollution monitoring stations. The sensor network will enable more comprehensive air quality coverage at much lower costs compared to adding more stations. New air quality maps, predictive air quality models and open data will be generated from the network and available to inform residents of at-risk areas.
Sensor networks are also becoming increasingly mobile, with several high-profile projects attaching sensors to moving objects such as cars and vans to provide insight on how air quality differs from street to street within cities. In Oakland, CA for example, the Environmental Defense Fund, Google Earth Outreach and researchers from the University of Texas at Austin partnered with Aclima to equip Google Street View cars with environmental monitoring sensors. The cars measured air pollution in three Oakland neighborhoods over a 1 year period. The resulting data showed that air pollution was far more variable than previously thought, often with significant changes occurring block to block.