According to Maslow’s hierarchy of human needs, air is at the very foundation of our needs. If you doubt that, feel free to hold the breath for a couple of minutes, and soon you will be convinced in this popular theory.
By 2050, it is projected that nearly 70 percent of the world’s population (around 6,7 billion people) will live in urban areas1. Greater concentration of people in one place carries many advantages, but also many drawbacks and challenges, especially those related to the environment.
Some studies show that people are breathing unsafe air in over 80% of cities globally, rising to 97% of cities in low and middle-income countries2. Globally, indoor and outdoor air pollution accounts for around 7 million deaths per year2, depending on the sources. Financial cost of air pollution is also substantial - roughly $900 billion per year in the USA only, or around 4,5% of US GDP3. Having that in mind, it is no wonder that public awareness about air quality has been growing lately, especially in those areas where air is categorized as unhealthy4.
One of the key contributors to the greater public awareness is the development of air quality sensors which can measure multiple parameters like air temperature, relative humidity, atmospheric pressure and concentrations of different gases and particles in the air. Having a good network of strategically positioned indicative air quality sensors is a prerequisite to modern air quality management. Such a network enables scientists and experts to assess the levels of air pollution in a much higher resolution which is a great addition to reference fixed measurement stations positioned in only a number of locations in the city. This highly localized data enables them to be better and more data-driven in identifying the sources of pollution and local hot-spots. This can (and should) lead to greater public awareness and development of regulatory framework. Once policies have been enforced, the network of air quality sensors serves as the tool to objectively measure the progress and effectiveness of those policies and to adjust them according to the gathered air quality data.
There is a number of examples in which cities can use this data in innovative ways to improve air quality. It is possible to combine air quality measurement data and geofencing to automatically switch the city’s fleet of hybrid vehicles to electric-only mode when entering areas with poor air. Another interesting example is using air quality data and Variable Message Signs (VMS) to display messages that encourage drivers and pedestrians entering areas with poor air, to consider alternative routes. It is not hard to imagine a next step in combining air quality data and VMS - traffic flow management system which will not just suggest, but also automatically alter possible traffic routes in the city based on air quality data.
Looking at the demographic, economic and environmental trends together with the development of the sensing technology, it becomes obvious that the real question is not “Should we measure the air quality data or not?”, but “How should we interpret and use air quality data gathered in cities?”.
 – Urbanization, Our World in Data - https://ourworldindata.org/urbanization#what-share-of-people-will-live-in-urban-areas-in-the-future
 – Why clean air is vital for your city’s health and prosperity, C40 Knowledge Hub - https://www.c40knowledgehub.org/s/article/Why-clean-air-is-vital-for-your-city-s-health-and-prosperity?language=en_US
 – 100,000 Americans Die from Air Pollution, Study Finds, U.S. News - https://www.usnews.com/news/national-news/articles/2019-04-08/100-000-americans-die-from-air-pollution-study-finds
 – AQI and AQ awareness among adults in the United States - https://stacks.cdc.gov/view/cdc/87167/cdc_87167_DS1.pdf