Articles | Volume 16, issue 19
https://doi.org/10.5194/amt-16-4357-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/amt-16-4357-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
05 Oct 2023
Research article |
| 05 Oct 2023
| 05 Oct 2023
Seasonally optimized calibrations improve low-cost sensor performance: long-term field evaluation of PurpleAir sensors in urban and rural India
Mark Joseph Campmier
Department of Civil and Environmental Engineering, University of California, Berkeley, Berkeley, CA 94720, USA
Jonathan Gingrich
Department of Engineering, Dordt University, Sioux Center, IA 51250, USA
Saumya Singh
Department of Civil and Environmental Engineering, University of California, Berkeley, Berkeley, CA 94720, USA
Nisar Baig
Department of Civil Engineering, Indian Institute of Technology Delhi, New Delhi, Delhi 110016, India
Shahzad Gani
Centre for Atmospheric Sciences, Indian Institute of Technology Delhi, New Delhi, Delhi 110016, India
Institute for Atmospheric and Earth System Research/Physics, University of Helsinki, Helsinki 00100, Finland
Adithi Upadhya
ILK Labs, Benson Town, Bengaluru 560046, India
Pratyush Agrawal
Center for Study of Science, Technology and Policy, Bengaluru 560094, India
Meenakshi Kushwaha
ILK Labs, Benson Town, Bengaluru 560046, India
Harsh Raj Mishra
Indo-Gangetic Plains Centre for Air Research and Education (IGP-CARE), Hamirpur 210301, India
Ajay Pillarisetti
School of Public Health, University of California, Berkeley, Berkeley, CA 94720, USA
Sreekanth Vakacherla
Center for Study of Science, Technology and Policy, Bengaluru 560094, India
Ravi Kant Pathak
Indo-Gangetic Plains Centre for Air Research and Education (IGP-CARE), Hamirpur 210301, India
Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
Joshua S. Apte
CORRESPONDING AUTHOR
Department of Civil and Environmental Engineering, University of California, Berkeley, Berkeley, CA 94720, USA
School of Public Health, University of California, Berkeley, Berkeley, CA 94720, USA
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EGUsphere, https://doi.org/10.5194/egusphere-2026-1189, https://doi.org/10.5194/egusphere-2026-1189, 2026
This preprint is open for discussion and under review for Atmospheric Measurement Techniques (AMT).
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Air pollution concentrations have high spatial variability that is not captured by regulatory monitoring. We developed and evaluated a mobile laboratory to map hundreds of gas and particle phase pollutants at meter-level resolution with open hardware and software designs. This blueprint will help researchers deploy similar tools to evaluate community concerns and local air quality issues from a huge variety of sources.
Yijing Chen, Cheng Wu, Epameinondas Tsiligiannis, Ravi Kant Pathak, Jan B. C. Pettersson, Harsh Raj Mishra, Gazala Habib, Geetam Tiwari, Kebin He, Jingkun Jiang, and Mattias Hallquist
EGUsphere, https://doi.org/10.5194/egusphere-2026-73, https://doi.org/10.5194/egusphere-2026-73, 2026
This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
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This work extends current understanding of atmospheric chemistry across different NO regimes in Delhi. Field measurements during the early springtime of 2023 show enhanced nighttime production of N2O5 and ClNO2, driven by decreased NO and high particulate chloride concentrations. The inert particulate chloride can be efficiently activated to photolabile gases with the reduction of NO, and contribute to secondary pollution by enhancing atmospheric organics oxidation in Delhi.
Aino Ovaska, Elio Rauth, Daniel Holmberg, Paulo Artaxo, John Backman, Benjamin Bergmans, Don Collins, Marco Aurélio Franco, Shahzad Gani, Roy M. Harrison, Rakesh K. Hooda, Tareq Hussein, Antti-Pekka Hyvärinen, Kerneels Jaars, Adam Kristensson, Markku Kulmala, Lauri Laakso, Ari Laaksonen, Nikolaos Mihalopoulos, Colin O'Dowd, Jakub Ondracek, Tuukka Petäjä, Kristina Plauškaitė, Mira Pöhlker, Ximeng Qi, Peter Tunved, Ville Vakkari, Alfred Wiedensohler, Kai Puolamäki, Tuomo Nieminen, Veli-Matti Kerminen, Victoria A. Sinclair, and Pauli Paasonen
Aerosol Research, 3, 589–618, https://doi.org/10.5194/ar-3-589-2025, https://doi.org/10.5194/ar-3-589-2025, 2025
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We trained machine learning models to estimate the number of aerosol particles large enough to form clouds and generated daily estimates for the entire globe. The models performed well in many continental regions but struggled in remote and marine areas. Still, this approach offers a way to quantify these particles in areas that lack direct measurements, helping us understand their influence on clouds and climate on a global scale.
Erin F. Katz, Caleb M. Arata, Eva Y. Pfannerstill, Robert J. Weber, Darian Ng, Michael J. Milazzo, Haley Byrne, Hui Wang, Alex B. Guenther, Camilo Rey-Sanchez, Joshua Apte, Dennis D. Baldocchi, and Allen H. Goldstein
Atmos. Chem. Phys., 25, 15281–15299, https://doi.org/10.5194/acp-25-15281-2025, https://doi.org/10.5194/acp-25-15281-2025, 2025
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Terpenoids are organic gases that can originate from natural and human-caused sources, and their reactions in the atmosphere can cause air pollution. In this study, emissions of organic gases in an urban environment were measured. For some terpenoids, human-caused sources were responsible for about a quarter of the emissions, while others were predominantly from vegetation. This study contributes to a better understanding of urban emission sources and causes of air pollution.
Shahzad Gani, Louise Arnal, Lucy Beattie, John Hillier, Sam Illingworth, Tiziana Lanza, Solmaz Mohadjer, Karoliina Pulkkinen, Heidi Roop, Iain Stewart, Kirsten von Elverfeldt, and Stephanie Zihms
Geosci. Commun., 7, 251–266, https://doi.org/10.5194/gc-7-251-2024, https://doi.org/10.5194/gc-7-251-2024, 2024
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Science communication in geosciences has societal and scientific value but often operates in “shadowlands”. This editorial highlights these issues and proposes potential solutions. Our objective is to create a transparent and responsible geoscience communication landscape, fostering scientific progress, the well-being of scientists, and societal benefits.
Bjorn Stevens, Stefan Adami, Tariq Ali, Hartwig Anzt, Zafer Aslan, Sabine Attinger, Jaana Bäck, Johanna Baehr, Peter Bauer, Natacha Bernier, Bob Bishop, Hendryk Bockelmann, Sandrine Bony, Guy Brasseur, David N. Bresch, Sean Breyer, Gilbert Brunet, Pier Luigi Buttigieg, Junji Cao, Christelle Castet, Yafang Cheng, Ayantika Dey Choudhury, Deborah Coen, Susanne Crewell, Atish Dabholkar, Qing Dai, Francisco Doblas-Reyes, Dale Durran, Ayoub El Gaidi, Charlie Ewen, Eleftheria Exarchou, Veronika Eyring, Florencia Falkinhoff, David Farrell, Piers M. Forster, Ariane Frassoni, Claudia Frauen, Oliver Fuhrer, Shahzad Gani, Edwin Gerber, Debra Goldfarb, Jens Grieger, Nicolas Gruber, Wilco Hazeleger, Rolf Herken, Chris Hewitt, Torsten Hoefler, Huang-Hsiung Hsu, Daniela Jacob, Alexandra Jahn, Christian Jakob, Thomas Jung, Christopher Kadow, In-Sik Kang, Sarah Kang, Karthik Kashinath, Katharina Kleinen-von Königslöw, Daniel Klocke, Uta Kloenne, Milan Klöwer, Chihiro Kodama, Stefan Kollet, Tobias Kölling, Jenni Kontkanen, Steve Kopp, Michal Koran, Markku Kulmala, Hanna Lappalainen, Fakhria Latifi, Bryan Lawrence, June Yi Lee, Quentin Lejeun, Christian Lessig, Chao Li, Thomas Lippert, Jürg Luterbacher, Pekka Manninen, Jochem Marotzke, Satoshi Matsouoka, Charlotte Merchant, Peter Messmer, Gero Michel, Kristel Michielsen, Tomoki Miyakawa, Jens Müller, Ramsha Munir, Sandeep Narayanasetti, Ousmane Ndiaye, Carlos Nobre, Achim Oberg, Riko Oki, Tuba Özkan-Haller, Tim Palmer, Stan Posey, Andreas Prein, Odessa Primus, Mike Pritchard, Julie Pullen, Dian Putrasahan, Johannes Quaas, Krishnan Raghavan, Venkatachalam Ramaswamy, Markus Rapp, Florian Rauser, Markus Reichstein, Aromar Revi, Sonakshi Saluja, Masaki Satoh, Vera Schemann, Sebastian Schemm, Christina Schnadt Poberaj, Thomas Schulthess, Cath Senior, Jagadish Shukla, Manmeet Singh, Julia Slingo, Adam Sobel, Silvina Solman, Jenna Spitzer, Philip Stier, Thomas Stocker, Sarah Strock, Hang Su, Petteri Taalas, John Taylor, Susann Tegtmeier, Georg Teutsch, Adrian Tompkins, Uwe Ulbrich, Pier-Luigi Vidale, Chien-Ming Wu, Hao Xu, Najibullah Zaki, Laure Zanna, Tianjun Zhou, and Florian Ziemen
Earth Syst. Sci. Data, 16, 2113–2122, https://doi.org/10.5194/essd-16-2113-2024, https://doi.org/10.5194/essd-16-2113-2024, 2024
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To manage Earth in the Anthropocene, new tools, new institutions, and new forms of international cooperation will be required. Earth Virtualization Engines is proposed as an international federation of centers of excellence to empower all people to respond to the immense and urgent challenges posed by climate change.
Anil Kumar Mandariya, Ajit Ahlawat, Mohammed Haneef, Nisar Ali Baig, Kanan Patel, Joshua Apte, Lea Hildebrandt Ruiz, Alfred Wiedensohler, and Gazala Habib
Atmos. Chem. Phys., 24, 3627–3647, https://doi.org/10.5194/acp-24-3627-2024, https://doi.org/10.5194/acp-24-3627-2024, 2024
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The current study explores the temporal variation of size-selected particle hygroscopicity in Delhi for the first time. Here, we report that the high volume fraction contribution of ammonium chloride to aerosol governs the high aerosol hygroscopicity and associated liquid water content based on the experimental data. The episodically high ammonium chloride present in Delhi's atmosphere could lead to haze and fog formation under high relative humidity in the region.
Sahil Bhandari, Zainab Arub, Gazala Habib, Joshua S. Apte, and Lea Hildebrandt Ruiz
Atmos. Chem. Phys., 22, 13631–13657, https://doi.org/10.5194/acp-22-13631-2022, https://doi.org/10.5194/acp-22-13631-2022, 2022
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Here we determine the sources of primary organic aerosol in Delhi, India, in two different seasons. In winter, the main sources are traffic and biomass burning; in the summer, the main sources are traffic and cooking. We obtain this result by conducting source apportionment resolved by time of day, using data from an aerosol chemical speciation monitor. Results from this work can be used to better design policies that target sources of organic aerosol.
Sahil Bhandari, Zainab Arub, Gazala Habib, Joshua S. Apte, and Lea Hildebrandt Ruiz
Atmos. Meas. Tech., 15, 6051–6074, https://doi.org/10.5194/amt-15-6051-2022, https://doi.org/10.5194/amt-15-6051-2022, 2022
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We present a new method to conduct source apportionment resolved by time of day using the underlying approach of positive matrix factorization. We report results for four example time periods in two seasons (winter and monsoon 2017) in Delhi, India. Compared to the traditional approach, we extract a larger number of factors that represent the expected sources of primary organic aerosol. This method can capture diurnal time series patterns of sources at low computational cost.
Benjamin Foreback, Lubna Dada, Kaspar R. Daellenbach, Chao Yan, Lili Wang, Biwu Chu, Ying Zhou, Tom V. Kokkonen, Mona Kurppa, Rosaria E. Pileci, Yonghong Wang, Tommy Chan, Juha Kangasluoma, Lin Zhuohui, Yishou Guo, Chang Li, Rima Baalbaki, Joni Kujansuu, Xiaolong Fan, Zemin Feng, Pekka Rantala, Shahzad Gani, Federico Bianchi, Veli-Matti Kerminen, Tuukka Petäjä, Markku Kulmala, Yongchun Liu, and Pauli Paasonen
Atmos. Chem. Phys., 22, 11089–11104, https://doi.org/10.5194/acp-22-11089-2022, https://doi.org/10.5194/acp-22-11089-2022, 2022
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This study analyzed air quality in Beijing during the Chinese New Year over 7 years, including data from a new in-depth measurement station. This is one of few studies to look at long-term impacts, including the outcome of firework restrictions starting in 2018. Results show that firework pollution has gone down since 2016, indicating a positive result from the restrictions. Results of this study may be useful in making future decisions about the use of fireworks to improve air quality.
Ying Zhou, Simo Hakala, Chao Yan, Yang Gao, Xiaohong Yao, Biwu Chu, Tommy Chan, Juha Kangasluoma, Shahzad Gani, Jenni Kontkanen, Pauli Paasonen, Yongchun Liu, Tuukka Petäjä, Markku Kulmala, and Lubna Dada
Atmos. Chem. Phys., 21, 17885–17906, https://doi.org/10.5194/acp-21-17885-2021, https://doi.org/10.5194/acp-21-17885-2021, 2021
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We characterized the connection between new particle formation (NPF) events in terms of frequency, intensity and growth at a near-highway location in central Beijing and at a background mountain site 80 km away. Due to the substantial contribution of NPF to the global aerosol budget, identifying the conditions that promote the occurrence of regional NPF events could help understand their contribution on a large scale and would improve their implementation in global models.
Shahzad Gani, Lukas Kohl, Rima Baalbaki, Federico Bianchi, Taina M. Ruuskanen, Olli-Pekka Siira, Pauli Paasonen, and Hanna Vehkamäki
Geosci. Commun., 4, 507–516, https://doi.org/10.5194/gc-4-507-2021, https://doi.org/10.5194/gc-4-507-2021, 2021
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In this article, we present authorship guidelines which also include a novel authorship form along with the documentation of the formulation process for a multidisciplinary and interdisciplinary center with more than 250 researchers. Our practical approach promotes fair authorship practices and, by focusing on clear, transparent, and timely communication, helps avoid late-stage authorship conflict.
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Short summary
We studied a low-cost air pollution sensor called PurpleAir PA-II in three different locations in India (Delhi, Hamirpur, and Bangalore) to characterize its performance. We compared its signal to more expensive reference sensors and found that the PurpleAir sensor was precise but inaccurate without calibration. We created a custom calibration equation for each location, which improved the accuracy of the PurpleAir sensor, and found that calibrations should be adjusted for different seasons.
We studied a low-cost air pollution sensor called PurpleAir PA-II in three different locations...
