LocationsLeveraging Low-Cost Sensor Solutions for Hyperlocal Air Quality Monitoring
August 21, 2024
Air Pollution and Health
Air pollution is a critical developmental threat, posing a global environmental and health crisis. Leading to approximately one in nine deaths worldwide, it imposes considerable economic burdens, accounting for the loss of 6.1% of the global gross domestic product in 2019. High air pollutant levels can cause health effects such as respiratory infections, heart disease, stroke, and lung cancer and disproportionately affects vulnerable populations such as those with existing illnesses, the elderly, pregnant women, and children. Other studies have also linked air pollution to cognitive impairment such as an increased risk of dementia and Alzheimer’s. In 2019, 89% of 4.2 million premature deaths worldwide caused by ambient (outdoor) air pollution occurred in low- and middle-income countries, with the highest numbers in Southeast Asia and Western Pacific regions. In the Asia-Pacific region, an estimated 92% of the population is exposed to hazardous air quality levels.
Status of Current Air Quality Monitoring
Based on a report Strengthening Air Quality Management Guidance developed by the Clean Air Fund, UN Environment Programme (UNEP), and Global Health Visions (GHV), less than a third of countries that were surveyed have successfully implemented monitoring networks or have air quality management (AQM) strategies. This is despite the substantial information on air quality monitoring available online such as from WHO, and UN organisations. The main barriers to establishing an air quality monitoring network highlighted in the report are lack of technical capacity and funding. The report emphasised that finding the most relevant guidance was tedious and that the content is often too technical for a reader that might not have the necessary prior knowledge of air quality. In addition, the dynamic nature of air quality, which comes from a multitude of sources and fluctuates over time and space, means that air pollution issues are unique based on the context within a city.
Proportion of countries with national ambient air quality monitoring networks
Currently, traditional air quality monitoring involves stationary, physical, and often costly equipment, also known as ‘regulatory’ or ‘reference’ sensors. These sensors are typically placed far apart (ranging between hundreds of metres to kilometres) and are not suitable for hyperlocal air quality monitoring. Comprehensive quality assurance and quality control (QA/QC), calibration, and maintenance plans are also required to ensure that the sensors are working properly and that the air quality data from the sensors are robust and accurate. Continuous and reliable data is necessary to be able to track the general ambient air quality within a city or country over a long-term period and to be able to capture elevated air quality levels during exceptional air pollution events.
Setting up an air quality monitoring network can be challenging, especially without sufficient technical guidance and financial resources. In this context, although low-cost air quality sensors (LCS) cannot replace traditional reference sensors in terms of accuracy, sensitivity or robustness, they have the potential to provide a general indicator of air quality levels. In setting up an LCS network, beginner air quality practitioners can also start developing the necessary technical capability in air quality monitoring. Subsequently, the data can be further assessed for accuracy and representativeness and used for planning air quality programmes within the city. In addition, expanding the accessibility and utilisation of LCS networks can result in wide-ranging and unique use cases by stakeholders other than the governments and academia, such as by private, non-profit companies, communities, and citizens, for example, to monitor hyperlocal air quality levels around schools.
‘Reference’ sensors vs low-cost sensors
LCS networks have been set up in many capital cities such as London, Nairobi, Paris, and many states in the U.S. For example, a network of 6 LCS was set up over 6 months at various sites in Nairobi including at the UN Environment Programme (UNEP) headquarters in Gigiri and in several schools. The data was compared against the WHO Ambient Air Quality Guidelines and used to carry out an exposure and health assessment study. More details on this and other examples will be explored in the next blog article.
Challenges in Setting up a Low-Cost Sensor Network
LCS are often influenced by environmental conditions such as temperature and humidity and as such need to be calibrated against reference sensors to improve accuracy. An LCS would need to be co-located against a reference sensor, in which a correction factor is derived between the co-located sensors and subsequently applied to the other LCS within a network.
Although LCS are less costly as compared to reference sensors, the existing market rate for LCS (i.e. SGD300 to SGD3,000 per sensor) may still not be affordable for countries, cities, and other potential user groups facing financial resource constraints. Typically, an LCS network would require around 10 sets of LCS or more to carry out hyperlocal air quality monitoring over a specific area of interest e.g. within a traffic zone. In addition, some technical knowledge in air quality monitoring is still needed for cities to set up an LCS network. Significant vendor support is needed for the setup, operation, maintenance, and data analyses of the LCS network, which adds recurrent costs on top of hardware costs.
UNDP Open Innovation Challenge for a Low-Cost Air Quality Monitoring Toolkit
Considering the potential of LCS and to solve the challenges associated with setting up and operating an LCS network, the UNDP Global Centre, in collaboration with Singapore’s Ministry of Sustainability and the Environment (MSE), has launched an Open Innovation Challenge to seek the development of a comprehensive, Do-It-Yourself (DIY), all-in-one low-cost air quality sensor toolkit on IMDA’s Open Innovation Platform. The toolkit will also be supplemented by additional educational material to equip the user with the necessary information to set up an LCS network independently and with minimal guidance.
The data from the LCS network has the potential to inform urban planning and development, guide public health initiatives, evaluate the effectiveness of environmental policies, empower local community engagement, and optimise transport and mobility management. The next blog article will explore a few examples of applications of LCS for air quality management to empower communities to drive action.