Recently, there have been significant advances in low-cost sensors (LCS) in air pollution monitoring. Our group is interested in understanding how these tools can help inform more rapid technology assessments or more quickly understand the impact of policy interventions. We have been working with multiple LCS and conducting experiments in locations like New Delhi and Jodhpur. A step beyond that, our team has been working on developing indegenous sensors as well.
Particulate matter (PM) is made of solid particles and liquid droplets in the air. Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye.Others are so small they can only be detected using an electron microscope. These particles come in many sizes and shapes and can be made up of hundreds of different chemicals. Most particles form in the atmosphere as a result of complex reactions of chemicals such as sulfur dioxide and nitrogen oxides, which are pollutants emitted from power plants, industries and automobiles.
Ground-level ozone is a colorless and highly irritating gas that forms just above the earth's surface. It is called a "secondary" pollutant because it is produced when two primary pollutants react in sunlight and stagnant air.
Low-cost particulate matter (PM) sensors have become in- creasingly popular due to their compact size, low power consumption, and cost-effective installation and maintenance. While several studies have explored the effects of meteorological conditions and pollution exposure on low-cost sensor (LCS) performance, few have addressed the combined impact of high PM concentration and high humidity levels. In contrast to most evaluation studies, which generally report PM2.5 levels below 150 μg/m3, our study observed hourly average PM2.5 concentra- tions ranging from 6 − 611 μg/m3 (mean value of 137 μg/m3), with relative humidity between 25 − 95% (mean value of 72%), and temperature varying from 6 − 29◦C (mean value of 16◦C). We evaluate three LCS models (SPS30, PMS7003, HPMA115C0-004) in outdoor conditions during the winter season in New Delhi, India, deployed alongside a reference-grade beta attenuation monitor (BAM).
This study involved a three-month collocated study of three sensor groups in Jodhpur, Rajasthan, which falls under a hot and dry climate. This study was an extension of our previous research conducted in Delhi, which was characterized by a composite climate. In this study, the raw sensor outputs were evaluated against the USEPA performance metrics, and the effectiveness of temperature and humidity corrections was also assessed. This research aimed to contribute to a better understanding of LCS performance in diverse Indian climates, ultimately helping to improve air quality monitoring and management in the country. Future experiments are planned to be conducted in other climatic zones across India.
This study involved a year-long collocated study of multiple sensor groups in Delhi, a region characterized by a composite climate with distinct seasonal variations, including hot, humid summers and cold winters. This extended study aimed to evaluate the long-term performance and stability (drift) of low-cost sensors (LCS) over varying weather conditions, such as temperature fluctuations and humidity changes. The raw sensor outputs were analyzed in alignment with USEPA performance metrics, with particular focus on the effects of seasonal drift and the reliability of temperature and humidity corrections over time. This research provides insights into the sustained performance of LCS for air quality monitoring across seasonal cycles, contributing to enhanced air quality management practices in urban Indian climates.
This study involved a one-month deployment of nine sensors from the same brand, grouped into three sets of three sensors each, to assess performance under varying conditions. The first set consisted of new sensors, the second set comprised sensors that had been in continuous use for one year, and the third set included sensors used intermittently in a previous study. To evaluate sensor functionality, the flow rates of each sensor were measured prior to deployment, and their stability and accuracy were monitored over the month-long period. This setup allowed for a comparative analysis of sensor drift across different usage durations, providing valuable insights into long-term performance and the impact of operational history on sensor reliability.
Our team is also focused on designing and developing a low-cost optical particle counter (OPC) capable of reliable operation in high particulate matter (PM) and high humidity conditions. This work addresses the challenges of sensor performance under extreme environmental stressors, aiming to improve measurement accuracy and durability in such demanding scenarios.
WS209, Central Workshop, IIT Delhi.
vyomaniitd@gmail.com
