How to measure air quality

The importance of monitoring air quality is evident in the impact pollutants have on human health, the environment, and the economy. By assessing the extent of air pollution through timely, accurate data, policies and standards can be enacted, control strategies can be evaluated, and research and models can be supported to mitigate the negative effects of pollutants for a better future. But how is air quality measured, exactly? Read on to find out.

Fixed automated monitoring stations

Fixed automated air quality monitoring stations are large, government-sanctioned, and are situated in fixed locations, with higher concentrations in areas where exposure to harmful pollutants is more likely. While air quality regulations vary from country to country, these stations all measure for the major pollutants that have a negative impact on human health in accordance to World Health Organization (WHO) guidelines. Raw data on air pollutants from these stations is gathered and presented in a comprehensible form known as an air quality index (AQI), which can be found on one’s government website. 

Pros of fixed automated monitoring stations include high accuracy and reliability in real-time. Cons are that they are expensive, costing between tens to even hundreds of thousands of dollars per station to purchase and set up. The real cost comes in operating them, which can cost up to hundreds of thousands of dollars per year. In addition, these stations also require lots of regular maintenance, and thereby a strong system of support staff.

Mobile monitoring instrumentation

Air quality can also be measured on moving vehicles such as trucks and airplanes that are equipped with the appropriate instruments. This is a flexible and cost-effective way to monitor air quality in communities and rural areas that don’t have fixed automated monitoring stations.

Similar to automated monitoring stations, pros of mobile monitoring include high accuracy if handled and deployed properly. Cons are that they are expensive, high-maintenance, and require the emissions of their carrier vehicles to be taken into account whilst measuring pollutant values to avoid data miscalculations. Additional cons specific to using planes for air quality monitoring include low resolution and the near real-time data transmissions.

Passive collectors

Passive air quality samplers are inexpensive, portable, and compact air pollutant sampling devices. They are used as a survey tool to determine baseline air pollution concentrations over a set time period ranging from 8 hours to one month. 

Pros of passive collectors are that they don’t usually require a power supply, are cheap to deploy, and are effective for the one-time assessment of a designated area. Cons are that they only provide the mean value for the tested period of time, thus offering no temporal resolution.

Satellites

Satellites play an important role in forecasting poor air quality through imaging from space. NASA, the European Space Agency (ESA), and South Korea have all teamed up for this international effort. In particular, the currently in-orbit Sentinel-5P from the ESA is capable of measuring trace gases and aerosols in the troposphere that affect air quality and the climate.

Pros of satellite monitoring include global coverage and free access to the technical data. The Sentinel-5P, for example, is capable of mapping the globe daily and contributes to the Copernicus Atmosphere Monitoring Service (CAMS), which provides aggregated information on worldwide air pollution, health, solar energy, greenhouse gases, and climate forcing. Cons of satellite monitoring include low resolution and the near real-time data transmissions.

Air quality sensors

Sensors like the ones offered by Breeze Technologies are small, convenient, lower-cost, and can be installed both indoors and outdoors. Not only is air pollution an issue outside, it can actually rise to alarming levels in homes and buildings as well, with the concentrations of certain pollutants being 2 to 10 times higher. These days, sensors all have smart and cloud capacities, which make it easy to track pollutant levels on any wifi-enabled device. As such, air quality sensors fill the necessary gap in air pollution measurement left by traditional, large monitoring systems thanks to their ease in scaling and versatility: it is now easier than ever to build an air quality network at just about anywhere, from offices to factories to cities.

Pros of air quality sensors are that they tend to be relatively low-cost and much more compact than traditional automated monitoring stations. This allows for many of them to be deployed at once, thus greatly increasing the possible temporal and spatial resolution. Cons are their propensity for inaccuracy if not handled properly from issues such as drift and aging, though these can be mitigated through regular calibration and automated plausibility checks. Data quality from sensors can therefore greatly vary from manufacturer to manufacturer. Thus, it is important to look for sensors that measure key pollutants affecting human health and deliver accurate, real-time values outlined by proper international and national air quality guidelines. In order to trust the quality of the sensors, look for ones that are used in many governmental and official organizational initiatives, like the ones by Breeze. Our work has even been profiled and endorsed by the European Commission, which you can find here.