Development of low-cost indoor air quality monitoring devices: Recent advancements

The use of low-cost sensor technology to monitor air pollution has made remarkable strides in the last decade. The development of low-cost devices to monitor air quality in indoor environments can be used to understand the behaviour of indoor air pollutants and potentially impact on the reduction of related health impacts. These user-friendly devices are portable, require low-maintenance, and can enable near real-time, continuous monitoring. They can also contribute to citizen science projects and community-driven science. However, low-cost sensors have often been associated with design compromises that hamper data reliability. Moreover, with the rapidly increasing number of studies, projects, and grey literature based on low-cost sensors, information got scattered. Intending to identify and review scientifically validated literature on this topic, this study critically summarizes the recent research pertinent to the development of indoor air quality monitoring devices using low-cost sensors. The method employed for this review was a thorough search of three scientific databases, namely: ScienceDirect, IEEE, and Scopus. A total of 891 titles published since 2012 were found and scanned for relevance. Finally, 41 research articles consisting of 35 unique device development projects were reviewed with a particular emphasis on device development: calibration and performance of sensors, the processor used, data storage and communication, and the availability of real-time remote access of sensor data. The most prominent finding of the study showed a lack of studies consisting of sensor performance as only 16 out of 35 projects performed calibration/validation of sensors. An even fewer number of studies conducted these tests with a reference instrument. Hence, a need for more studies with calibration, credible validation, and standardization of sensor performance and assessment is recommended for subsequent research

Application of the low-cost sensing technology for indoor air quality monitoring: A review

In recent years, low-cost air pollution technologies have gained increasing interest and, have been studied widely by the scientific community. Thus, these new sensing technologies must provide reliable data with good precision and accuracy. Accordingly, this review aimed to evaluate and compare the low-cost sensing technology against other instruments used for comparison by various studies from the scientific literature to monitor indoor air quality in different indoor environments. After exclusions, a total of 42 studies divided into two subsections (11 laboratory studies and 31 field studies) were analysed considering their aim, location, study duration, sampling area, pollutant(s) evaluated, sensor/device and instrument used for comparison, performance indexes and main outcomes.& nbsp;The reviewed studies aimed to assess different low-cost sensors/devices to monitor indoor air quality against other instruments used for comparison. The vast majority of the studies took place in USA. The laboratory studies were mainly conducted in a controlled chamber, and field studies were performed in homes, offices, educational buildings, among others. In both cases, particulate matter was the most assessed pollutant, either with commercial devices (e.g.: Speck, Dylos, Foobot) or sensors (e.g. Sharp GP2Y1010AU0F). In general, based on statistical parameters, the air quality low-cost sensors/devices tested presented moderate correlations with the instruments used for comparison, revealing sufficient precision for monitoring air quality in indoor microenvironments, especially for qualitative analysis. Thus, low-cost sensing technology to monitor indoor air quality is encouraged, but not waiving the relevance of high quality instruments (mainly reference instruments).& nbsp;(c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Water Quality Measurement and Filtering Tools Using Arduino Uno, PH Sensor and TDS Meter Sensor

Rusunawa Rejosari is a flats owned by the Pekanbaru city government which is inhabited by underprivileged residents, water in the Rusunawa Rejosari borehole emits an unpleasant and murky odor, making it unfit for consumption and use for daily needs by residents who live there. Indonesia issued the TDS Standard by the Ministry of Health and the Indonesian National Standard (SNI), which is a maximum value of 500 ppm TDS and for the standard Hydrogen Potential (PH) of clean water 6.6 - 9.0 PH. Based on the above problems, a Water Quality Measurement and Filtration Tool was made using Arduino, a Hydrogen Potential Sensor (PH) and a Total Dissolved Solids (TDS) Sensor. Based on the research that has been carried out, it can be concluded that the tool runs smoothly, as evidenced by the measurement results of the accuracy of the sensor and successfully filters the water when the measurement is not normal, so that the water is suitable for consumption and use

Effects of operating a solar air heater on the indoor air quality in classrooms during the winter : a case study of Palmerston North primary schools : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy (PhD) in Building Technology at Massey University, Auckland, New Zealand

Schools are densely populated places, where children spend a large amount of their time. The indoor air quality (IAQ) in classrooms impacts students’ health, academic outcomes and school absences (Borras-Santos et al., 2013; Mi et al., 2006; Shendell, Prill, et al., 2004; Smedje and Norbäck, 2000; Taskinen et al., 2007). Three New Zealand (NZ) studies have found low ventilation rates, low temperature levels, high relative humidity (RH) levels and high carbon dioxide (CO2) levels during the winter months in NZ primary schools (Bassett and Gibson, 1999; Cutler-Welsh, 2006; McIntosh, 2011). These results show a need to improve the indoor environment in NZ schools during the winter. NZ school hours, from 9 am to 3 pm, are well aligned with the optimum solar radiation and classrooms lend themselves to heat from solar energy. A project was undertaken to investigate if operating a roof-mounted solar air heater (SAH) could improve the classroom IAQ during the winter. This two-year crossover project was undertaken in four Palmerston North (PN), NZ primary schools in 2013 and six PN, NZ primary schools in 2014. These consisted of the four schools participated in 2013 plus two additional schools. In each school, two adjacent classrooms with similar construction characteristics and population characteristics participated in this project. The two adjacent classrooms were randomly assigned either to a treatment group (SAH installed and operated) or to a control group (SAH installed but not operated). The main objective of this project was to investigate the change in levels of the classroom temperature, RH, CO2, and ventilation rate from when a roof-mounted SAH was operating (treatment) and was not operating (control). Resulting from operating the roof-mounted SAH, the temperature in treatment classrooms was on average 0.5 °C higher than in the control classrooms, when both the control and treatment classrooms had the same heater use. When the control and treatment classrooms achieved the same temperature, the heater use in the treatment classrooms was 27% less than the heater use in the control classrooms. Across all schools, CO2 levels in the treatment classrooms were on average 96 ppm lower than in the control classrooms. In five out of 10 schools (50%), the levels of CO2 in the treatment classrooms were lower than in the control classrooms. Only in one treatment classroom did the ventilation rate meet the NZ Ministry of Education recommended level of 4 air changes per hour. Overall, operating a roof-mounted SAH played a positive role in increasing the temperature and ventilation rate in classrooms during the winter. However, there was not sufficient airflow to satisfy the ventilation requirements. Future research should investigate the impact of operating a SAH on the school ventilation and temperature considering increasing the SAH outlet air volumetric flow rate and keeping the outlet air temperature around 18 °C to bring more heated air into classrooms

Deployment issues for integrated open-source-Based indoor air quality school Monitoring Box (SKOMOBO)

A low-cost, low power consumption indoor environment monitoring device, called SKOMOBO (SKOol Monitoring Box), was developed. SKOMOBO includes the sensors to monitor temperature/relative humidity, carbon dioxide, particulate matter (PM) and motion (PIR). SKOMOBO was developed using the open source software on Arduino Pro Mini. 165 units of SKOMOBO were manufactured at Massey University (New Zealand) in September 2017. These units were then deployed across New Zealand to monitor the indoor air quality in primary school classrooms. This paper describes the practical deployment issues we faced and lessons learnt prior/during the field study aimed at understanding the connection between the air quality and student performance. We believe that the discussion in this paper is of importance and could potentially save a lot of money and effort for other similar sensor products