Outdoor Air Quality Research Articles

An overview of outdoor low-cost gas-phase air quality sensor deployments: current efforts, trends, and limitations

Abstract. We reviewed 60 sensor networks and 17 related efforts (sensor review papers and data accessibility projects) to better understand the landscape of stationary low-cost gas-phase sensor networks deployed in outdoor environments worldwide. This study is not exhaustive of every gas-phase sensor network on the globe but rather exists to categorize types of sensor networks by their key characteristics and explore general trends. This also exposes gaps in monitoring efforts to date, especially regarding the availability of gas-phase measurements compared to particulate matter (PM) and geographic coverage gaps (the Global South, rural areas). We categorize ground-based networks that measure gas-phase air pollutants into two main subsets based on their deployment type – quasi-permanent (long term) and campaign (short to medium term) – and explore commonplace practices, strengths, and weaknesses of stationary monitoring networks. We conclude with a summary of cross-network unification and quality control efforts. This work aims to help scientists looking to build a sensor network explore best practices and common pathways and aid end users in finding low-cost sensor datasets that meet their needs.

Characteristics of PM2.5-bound water-soluble inorganic ions generated during cooking

Commercial cooking is an important source of PM2.5, which adversely affects air quality, posing threats to human health. However, few studies have examined the effects of commercial cooking on outdoor air quality. We aimed to analyze characteristics of outdoor PM2.5 and ions from commercial cooking during cooking and non-cooking times in a popular restaurant area at Nankai University. The acidity and alkalinity of atmospheric PM2.5 based on the equivalent values of anions and cations and the formed compounds based on the ion concentrations and correlations between them were determined. The results showed that the mean PM2.5 concentration at the snack street during cooking times was 120.39 ± 58.52 μg/m3, approximately 1.4 times higher than at the comparison point. The total concentration of water-soluble inorganic ions accounted for approximately half of the PM2.5 emissions at both sampling points. High concentrations of Na+, NO3−, and SO42− were found at both sampling points. We found that NH4NO3, CaSO4, and CaCl2 formed at the snack street, whereas Ca(NO3)2, NH4NO3, and (NH4)2SO4 formed at the comparison point. Based on our analysis of the acid-base balance slopes, the atmospheric PM2.5 was alkaline. These results elucidate the characteristics of PM2.5-bound water-soluble inorganic ions formed during cooking.

Comprehensive analysis of particulate matter, gaseous pollutants, and microbiological contamination in an international chain supermarket

Indoor environmental quality is of utmost importance since urban populations spend a large proportion of their life in confined spaces. Supermarkets offer a wide range of products and services that are prone to emitting several air pollutants. This study aimed to perform a comprehensive characterisation of the indoor and outdoor air quality in a multinational supermarket, encompassing not only criteria parameters but also unregulated pollutants of concern. Monitoring included measurements of comfort parameters, CO2, multiple gaseous pollutants, particulate matter (PM10) and bioburden. PM10, volatile organic compounds (VOCs) and carbonyls were subject to chemical speciation. Globally, the supermarket presented CO2, VOCs, and PM10 values below the limits imposed by international regulations. The PM10 concentration in the supermarket was 33.5±23.2 μg/m3, and the indoor-to-outdoor PM10 ratio was 1.76. Carbonaceous constituents represented PM10 mass fractions of 21.6% indoors and 15.3% outdoors. Due to the use of stainless-steel utensils, flour and fermentation processes, the bakery proved to be a pollution hotspot, presenting the highest concentrations of PM10 (73.1±9.16 μg/m3), PM10-bound elements (S, Cl, K, Ca, Ti, and Cr) and acetaldehyde (42.7 μg/m3). The maximum tetrachloroethylene level (130 μg/m3) was obtained in the cleaning products section. The highest values of colony-forming units of bacteria and fungi were recorded in the bakery, and fruit and vegetable section. The most prevalent fungal species was Penicillium sp., corresponding to 56.9% of the total colonies. In addition, other fungal species/sections with toxicological or pathogenic potential were detected (Aspergillus sections Aspergilli, Circumdati, Flavi, Mucor and Fusarium sp.).

Schools and Indoor Air Quality: seasonal variation

Abstract Background Indoor Air Quality (IAQ) in schools is a public health concern, given the vulnerability of children as a demographic group and substantial amount of time that they spend in (highly occupied) classrooms. Conditions specific for school buildings, as well as location and outdoor air quality (OAQ), can adversely affect IAQ and children’s health. The aim of this study was to examine the seasonal variation in IAQ and the influence of OAQ herein in primary schools. Methods Sampling was carried out in summer and winter in 5 schools in central Poland. A culture-dependent method using impactors was applied to examine the total number of bacteria and fungi. Gas chromatography with flame ionization detector (quartz filters for sampling) was applied to determine concentrations of 16 polycyclic aromatic hydrocarbons (PAHs), crucial for their health impact. Results In poorly ventilated classrooms bacteria levels exceeded that of fungi. Bacterial contamination decreased in efficiently ventilated rooms, and before/after the lessons. In summer fungi concentration in indoor air was higher than in winter and reached the level of fungi outdoors. PAHs concentrations (especially those with 4 and more rings, which are biologically active) and the mutagenicity and carcinogenicity equivalents were elevated in winter and related to changes in concentrations in outdoor air. Conclusions IAQ in schools depends on a season. Occupants in classrooms are the main source of bacteria, but the type and number of microorganisms also depend on ventilation conditions. PAHs characteristic of coal/wood combustion indicates that in the absence of internal emission sources, external sources most likely affect IAQ in schools in winter.

Health Effects of Climate Change in the UK report 2023

Abstract The fourth Health Effects of Climate Change in the UK report (HECC) was published by the UK Health Security Agency in 2023. The report brings together 15 independent chapters written by 90 experts from UK and international academic and research institutions and UKHSA. It provides an authoritative summary of the scientific evidence on the health effects of climate change in the UK, potential implications for public health and gaps in evidence. Chapters include a combination of new empirical analyses (using the most updated climate data - UKCP18 projections) and synthesis of new evidence. Topics covered include future UK climate, temperature effects on mortality, flooding, outdoor and indoor air quality, aeroallergens, infectious diseases, vector-borne diseases, food supply, wildfires, drought, human exposure to chemicals, solar radiation, health impacts of net zero and indicators for climate change and public health tracking.

Public perceptions of the health impacts of climate change: a survey study in Greece

Abstract Background Climate change is the biggest global health threat of the 21st century. Despite the tremendous challenges, many people remain unaware of the human health implications of climate change. People perceptions about the health harms of climate change can increase public support for the action needed to reduce climate change. The aim of this study was to examine the public perception of climate change as a human health issue in Greece. Methods A population survey study was conducted from October to December 2023 in the municipalities of Messini and Alexandroupoli, Greece, following proportional quota sampling. A questionnaire was developed and included measures about the socio-demographic background of participants, their understanding of key facts about climate change and their views about climate change thread to human health. Results 406 individuals with a mean age 37.7 (sd = 14.8) participated in the study. Participants understood that climate change is happening (93.6%) and 54% of them think climate change is mostly or entirely caused by human activities, whereas 38% think it is caused equally by human activities and natural causes, and about 8% think climate change is mostly or entirely caused by natural causes. A majority of participants reported that climate change has adversely affected the health of people in various way, either a moderate amount or a great deal, including physical or mental harm from forest fires (90%), physical or mental harm from storms and floods (87%), heat-related illnesses (82%), illness due to reduced outdoor air quality (70%) and loss of housing for residents displaced by extreme weather events (70%). Conclusions Participants viewed climate change as an important cause of health harm, however they partially understood that climate change is caused by humans. Public health authorities should educate the public and policymakers about the climate change and advocate for policies to address the human health challenges of climate change. Key messages • Public health authorities should educate the public and policymakers about the climate change problem and its impact to human health. • Providing people with information about the health harms of climate change can increase public support for the actions needed to reduce emissions.

Impacts of Indoor Air Quality on Working‐Age Populations' Subjective Well‐Being: Evidence From China Labor Dynamics Survey

ABSTRACTOutdoor air pollution can affect physical labor productivity and mental health, but it remains to be studied how indoor air quality (IAQ) exposure affects working‐age populations' subjective well‐being and physical health. Here, the first evidence of a link between IAQ and the subjective well‐being of working‐age populations has been provided using the dataset from a longitudinal survey in China. Using household ventilation as an instrument variable (IV) of IAQ revealed that IAQ improvements increased working‐age populations' subjective well‐being and life satisfaction by significantly affecting their physical health. Our analysis shows that an increase in IAQ by one standard deviation improves working‐age populations' subjective well‐being by 0.041 standard deviations. The marginal willingness to pay for IAQ is approximately 98.09 CNY. Compared with outdoor air quality, the impact of IAQ on well‐being and life satisfaction is more conspicuous. The results are robust to a variety of alternative specifications. For developing countries, improving IAQ is a new channel toward enhancing life quality, with lower economic and social costs.

Characterizing multifaceted environmental risks of oil and gas well leakage through soil and well methane and hydrogen sulfide emissions

Oil and gas wells (OGWs) can lead to soil and well emissions of methane (CH4), a potent greenhouse gas, and hydrogen sulfide (H2S), a highly toxic gas, both of which reduce air quality and can cause explosions when emitted into confined spaces. Developments have been occurring over OGWs, posing larger health and safety risks. However, to our knowledge, previous studies have not conjunctively analyzed well and soil emissions while considering development on or near OGWs. In this paper, we characterize 343 CH4 and H2S emission rate measurements from 67 non-producing (abandoned) and 35 producing (active) OGWs, including 205 measurements from soils surrounding 81 OGWs in Ontario and Quebec. We also provide the first emission rate estimates from an abandoned water and OGW-linked explosion and map OGWs in urban and built-up areas in Ontario and Quebec. We estimate the explosion-linked emissions to be 3,000 g CH4/hour and 7 g H2S/hour. Moreover, we find that 7,264 and 161 OGWs in Ontario and Quebec, respectively, are in urban and built-up areas, with 94% of these wells being abandoned. For the 102 wells we measured, we find OGW emission rate ranges of -16 to 47,000 mg CH4/hour and 0.001 to 3,300 mg H2S/hour, with 9% of the wells having positive detections of H2S. Although soil CH4 emissions at a 1-meter distance from the wells are most correlated with well emissions, the highest soil emission rate was observed at a 3-meter distance, indicating the potential for OGW-related emissions into buildings to occur away from the well. Overall, our multi-faceted measurement dataset provides a basis for conjunctive analysis of the broad range of environmental risks of OGWs to climate, indoor and outdoor air quality, and explosions.

Democratizing air: A co-created citizen science approach to indoor air quality monitoring

Indoor air quality (IAQ) is crucial for public health, yet many remain unaware of indoor pollutants. Although Citizen Science has enhanced outdoor air quality understanding, its application to IAQ remains underexplored. This study introduces a new co-creation methodology that addresses key limitations in existing IAQ monitoring practices by integrating value-sensitive design principles and a ‘facilitated emergence’ paradigm. Through three co-creation workshops, we engaged multiple stakeholders in every stage, from problem definition to data interpretation. We employed adaptive facilitation strategies to effectively balance power dynamics among stakeholders, ensuring inclusive decision-making and mitigating potential biases. Our 30-day data collection campaign provided real-time measurements of Particulate Matter (PM) concentrations. Analysis revealed several locations with Indoor/Outdoor (I/O) PM2.5 ratios close to or above 1, uncovering hidden IAQ complexities and emphasizing the need for localized monitoring. We showed how citizen-generated data can improve spatial resolution, detecting local variations missed by official networks. Feedback from the co-creation workshops demonstrated shifts in participants’ perceptions regarding IAQ, accountability, and their role in environmental decision-making, moving from passive awareness to active engagement. Our findings demonstrate how this value-sensitive and community-driven bottom-up approach can enhance air quality assessment, inform targeted IAQ management strategies, and empower citizens in environmental health decisions.

Air Cleaning Plants

Air quality, both outdoor and indoor, is the most critical element that we must protect for the entire environment. While the deterioration of air quality primarily causes respiratory diseases in living things, it also causes corrosive effects on nonliving things, such as corrosion caused by acid rain, which results from air pollution. Therefore, it is necessary to monitor and prevent air pollution by various methods. WHO plays an active role in protecting air quality through its mission. Plants are indispensable beings for the environment and life. They balance the CO2 concentration, temperature, and humidity in the air. Plants use CO2, light, and water during photosynthesis, which is necessary for their growth and development. They reduce the CO2 concentration in the environment. In addition, plants, depending on their leaf characteristics, can trap particulate matter in the atmosphere. Many studies have proven that plants positively affect indoor and outdoor air quality. In this review, we aim to summarize the results of some selected studies, provide information about the air purification capacities of the researched plants, and emphasize the topic's importance.

Multi-Junction Solar Module and Supercapacitor Self-Powering Miniaturized Environmental Wireless Sensor Nodes

A novel prototype based on the combination of a multi-junction, high-efficiency photovoltaic (PV) module and a supercapacitor (SC) able to self-power a wireless sensor node (WSN) for outdoor air quality monitoring has been developed and tested. A PV module with about an 8 cm2 active area made of eight GaAs-based triple-junction solar cells with a nominal 29% efficiency was assembled and characterized under terrestrial clear-sky conditions. Energy is stored in a 4000 F/4.2 V supercapacitor with high energy capacity and a virtually infinite lifetime (104 cycles). The node power consumption was tailored to the typical power consumption of miniaturized, low-consumption NDIR CO2 sensors relying on an LED as the IR source. The charge/discharge cycles of the supercapacitor connected to the triple-junction PV module were measured under illumination with a Sun Simulator device at selected radiation intensities and different node duty cycles. Tests of the miniaturized prototype in different illumination conditions outdoors were carried out. A model was developed from the test outcomes to predict the maximum number of sensor samplings and data transmissions tolerated by the node, thus optimizing the WSN operating conditions to ensure its self-powering for years of outdoor deployment. The results show the self-powering ability of the WSN node over different insolation periods throughout the year, demonstrating its operation for a virtually unlimited lifetime without the need for battery substitution.

Impact of Kitchen Natural Gas Use on Indoor NO2 Levels and Human Health: A Case Study in Two European Cities

Natural gas (NG) is commonly used in kitchens, powering stoves, ovens, and other appliances. While it is known for its efficiency and convenience, NG contributes to the release of nitrogen dioxide (NO2) and can have significant implications for human health. In this study, the importance of the use of NG in kitchens on human exposure to NO2 was analyzed. An extensive literature review in the field was conducted, and the NO2 levels were assessed in kitchens with NG cookers in Aveiro and electric cookers in Porto, both in Portugal. Higher levels of NO2 were found in kitchens in Aveiro, where NO2 levels outdoors are lower than in Porto. This pollutant can spread to other rooms, especially when ventilation is lacking, which is particularly concerning during colder seasons and at night. As around 70% of the time is spent at home, this can have a significant impact on human exposure to NO2. Therefore, although Aveiro has low levels of NO2 outdoors, its population may be exposed to much higher levels of this pollutant than the Porto population, a city with air quality issues, but predominantly using electric cookers. This finding emphasizes the need for the stricter regulation of NG use indoors to protect human health and also suggests a shift in human health protection policies from mere monitoring/control of outdoor air quality to a comprehensive assessment of human exposure, including exposure to indoor air quality.

AI-driven ventilation control policy proximal optimization coupled with dynamic-informed real-time model calibration for healthy and sustainable indoor PM2.5 management

Indoor air quality (IAQ) is an important factor for determining quality of life and urban sustainability. In underground subway stations, improving IAQ through ventilation systems remains challenging due to the complexity and nonstationary nature of IAQ resulting from diverse influential factors such as subway schedules, passenger volume, and outdoor air quality (OAQ). Therefore, this study aimed to develop a novel artificial intelligence (AI)-driven ventilation system for healthy and sustainable IAQ management in subway stations. First, an IAQ mechanistic model coupled with genetic algorithm (GA)-driven rolling-horizon calibration was developed from the collected IAQ big dataset, and global sensitivity analysis was then employed to identify the dominant variables in IAQ dynamics. Subsequently, proximal policy optimization (PPO), one of the reinforcement learning (RL) algorithms, was employed to control the ventilation system in both the lobby and platform areas of a subway station. The results demonstrated that the IAQ mechanistic model can capture IAQ dynamics with acceptable modeling performance, achieving around 19 % of mean absolute percentage error (MAPE). Furthermore, the PPO-driven ventilation control system can reduce energy consumption by around 22 % while maintaining IAQ at an acceptable level.

Risk perceptions of Italian paediatricians for the impact of climate change on children’s health

BackgroundsThis study delves into the risk perceptions of Italian pediatricians concerning climate change's impact on children's health. Given children's heightened vulnerability to climate-related health risks, comprehending these perceptions is crucial. A review of pertinent literature establishes the framework, emphasizing six key factors influencing children's susceptibility to climate-related health hazards.MethodsMethodologically, the study utilized a survey tool developed collaboratively with the Italian Society of Pediatrics (SIP), garnering responses from a representative sample of Italian pediatricians.ResultsFindings indicate a high level of awareness among respondents regarding climate change and its health implications, with a majority attributing it primarily to human activity. Pediatricians recognize various current and anticipated health impacts of climate change, notably concerning illnesses linked to outdoor air quality. Despite acknowledging their role in addressing climate-related health concerns, respondents also cite barriers to engagement, including time constraints and knowledge gaps. However, they express interest in resources like professional training and policy statements to bolster their capacity for effective communication and advocacy.ConclusionsComparisons with prior studies highlight the consistency of findings across diverse contexts and underscore the significance of integrating climate and environmental health education into medical training. Overall, this study sheds light on pediatricians' perspectives in tackling the convergence of climate change and children's health, pinpointing avenues for enhancing their involvement in climate advocacy and mitigation efforts.

Feasibility Study on the Use of NO2 and PM2.5 Sensors for Exposure Assessment and Indoor Source Apportionment at Fixed Locations.

Recent advances in sensor technology for air pollution monitoring open new possibilities in the field of environmental epidemiology. The low spatial resolution of fixed outdoor measurement stations and modelling uncertainties currently limit the understanding of personal exposure. In this context, air quality sensor systems (AQSSs) offer significant potential to enhance personal exposure assessment. A pilot study was conducted to investigate the feasibility of the NO2 sensor model B43F and the particulate matter (PM) sensor model OPC-R1, both from Alphasense (UK), for use in epidemiological studies. Seven patients with chronic obstructive pulmonary disease (COPD) or asthma had built-for-purpose sensor systems placed inside and outside of their homes at fixed locations for one month. Participants documented their indoor activities, presence in the house, window status, and symptom severity and performed a peak expiratory flow test. The potential inhaled doses of PM2.5 and NO2 were calculated using different data sources such as outdoor data from air quality monitoring stations, indoor data from AQSSs, and generic inhalation rates (IR) or activity-specific IR. Moreover, the relation between indoor and outdoor air quality obtained with AQSSs, an indoor source apportionment study, and an evaluation of the suitability of the AQSS data for studying the relationship between air quality and health were investigated. The results highlight the value of the sensor data and the importance of monitoring indoor air quality and activity patterns to avoid exposure misclassification. The use of AQSSs at fixed locations shows promise for larger-scale and/or long-term epidemiological studies.

Atmospheric aldehydes in indoor and outdoor environments impacted by combustion emissions of diesel/biodiesel mixtures

The temporal evolution of air pollutants concentrations inside a semi-closed bus station has been investigated since 2002 until 2023 to understand the impact of direct combustion emissions from buses using diesel/biodiesel fuel blends (B3-B12). Carbonyl compounds concentrations were evaluated, which predominance of acetaldehyde and formaldehyde. It is known that acrolein emission increases with the addition of biodiesel to diesel. However, the determination of acrolein by the official method is compromised due to coelution with acetone on liquid chromatographic separation. In this work, with adaptation of the mobile phase, acrolein was separated adequately and could be determinate in samples obtained in the same bus station while the vehicles had been using B12 fuel blends. Concomitantly, samples were collected outside the station to compare indoor and outdoor air quality. Formaldehyde, acetaldehyde and acrolein were detected in both environments. Aldehydes concentration was higher indoor than outdoors. There are indications that acrolein levels may increase with higher proportions of biodiesel in diesel blends. This study valuable information for future studies on air quality and vehicular emissions.

Using Indoor and Outdoor Measurements to Understand Building Protectiveness against Wildfire, Atmospheric Inversion, and Firework PM2.5 Pollution Events

The world has seen an increase in the frequency and severity of elevated outdoor pollution events exacerbated by the rise in distant polluting events (i.e., wildfires). We examined the intersection between indoor and outdoor air quality in an urban area using research-grade sensors to explore PM2.5 infiltration across a variety of pollution events by testing two separate indoor environments within the same building. We confirmed prior work suggesting that indoor environments in buildings are most protective during wintertime inversion events and less so during fireworks and wildfire events. The building indoor environment protectiveness varies notably during different pollution episodes, especially those that have traveled longer distances (e.g., wildfires), and we found evidence of varied infiltration rates across PM2.5 types. Inversion events have the lowest infiltration rates (13–22%), followed by fireworks (53–58%), and wildfires have the highest infiltration rates (62–70%), with distant wildfire events persisting longer and, therefore, infiltrating for greater durations than local-wildfire-related particle matter. The differences in PM infiltration rates were likely due to the combined effects of several factors, including varying particle size, concentration, and chemistry. Subsequently, the local wildfires had different temporal air quality impacts than distant wildfire pollution in this case. Based on these findings, indoor air quality appears more conducive to protective action and policies than outdoor air quality because the built environment may serve to shield individuals from outdoor air.

Assessing the Impact of Spatial and Temporal Variability in Fine Particulate Matter Pollution on Respiratory Health Outcomes in Asthma and COPD Patients.

Ambient air pollution's health impacts are well documented, yet the domestic environment remains underexplored. We aimed to compare indoor versus outdoor (I/O) air quality and estimate the association between indoor/ambient fine particulate matter (PM2.5) exposure and lung function in asthma and chronic obstructive pulmonary disease (COPD) patients. The study involved 24 h monitoring of PM2.5 levels indoors and outdoors, daily peak expiratory flow (PEF), and biweekly symptoms collection from five patients with asthma and COPD (average age of 50 years, 40% male) over a whole year. Data analysis was performed with linear mixed effect models for PEF and generalized estimating equations (GEE) for exacerbations. More than 5 million PM2.5 exposure and meteorological data were collected, demonstrating significant I/O PM2.5 ratio variability with an average ratio of 2.20 (±2.10). Identified indoor PM2.5 sources included tobacco use, open fireplaces, and cooking, resulting in average indoor PM2.5 concentrations of 63.89 μg/m3 (±68.41), significantly exceeding revised World Health Organization (WHO) guidelines. Analysis indicated a correlation between ambient PM2.5 levels and decreased PEF over 0-to-3-day lag, with autumn indoor exposure significantly impacting PEF and wheezing. The study underscores the need to incorporate domestic air quality into public health research and policy-making. A personalized approach is required depending on the living conditions, taking into account the exposure to particulate pollution.

NOx Abatement by a TiO2-Based Coating under Real-Life Conditions and Laboratory-Scale Durability Assessment

In urban environments, various pollutants generated by road traffic, human, and industrial activities degrade outdoor and indoor air quality. Among these pollutants, nitrogen oxides (NOx) are subject to air quality regulations designed to protect human health and the environment. It is therefore crucial to keep their concentration as low as possible. Advanced oxidation processes are a practical choice for the degradation of NOx; among them, heterogeneous photocatalysis has proven to be a viable route. However, while the efficiency of this process has been widely demonstrated on a laboratory scale, it is still the subject of debate for real-life applications. The purpose of this study was to present a new field experiment on the application of a photocatalytic coating to outdoor walls. Air quality monitoring stations were used to evaluate the NOx concentration reduction instead of the chemiluminescent analyzer, in order to increase the number of sampling points. Statistical analysis was carried out to interpret the results. Density probability functions were plotted and showed a positive impact of the coating, leading to lower NOx concentrations. This work was completed by a laboratory-scale assessment of the coating’s durability using abrasion, QUV, and immersion/drying tests. The air depollution capacity of the chosen coating was significantly reduced after QUV testing.

Assessing bias in personal exposure estimates when indoor air quality is ignored: A comparison between GPS-enabled mobile air sensor data and stationary outdoor sensor data

Neglecting indoor air quality in exposure assessments may lead to biased exposure estimates and erroneous conclusions about the health impacts of exposure and environmental health disparities. This study assessed these biases by comparing two types of personal exposure estimates for 100 individuals: one derived from real-time particulate matter (PM2.5) measurements collected both indoors and outdoors using a low-cost portable air monitor (GeoAir2.0) and the other from PurpleAir sensor network data collected exclusively outdoors. The PurpleAir measurement data were used to create smooth air pollution surfaces using geostatistical methods. To obtain mobility-based exposure estimates, both sets of air pollution data were combined with the individuals' GPS tracking data. Paired-sample t-tests were then performed to examine the differences between these two estimates. This study also investigated whether GeoAir2.0- and PurpleAir-based estimates yielded consistent conclusions about gender and economic disparities in exposure by performing Welch's t-tests and ANOVAs and comparing their t-values and F-values. The study revealed significant discrepancies between GeoAir2.0- and PurpleAir-based estimates, with PurpleAir data consistently overestimating exposure (t = 5.94; p < 0.001). It also found that females displayed a higher average exposure than males (15.65 versus. 8.55 μg/m3) according to GeoAir2.0 data (t = 4.654; p = 0.055), potentially due to greater time spent indoors engaging in pollution-generating activities traditionally associated with females, such as cooking. This contrasted with the PurpleAir data, which indicated higher exposure for males (43.78 versus. 46.26 μg/m3) (t = 3.793; p = 0.821). Additionally, GeoAir2.0 data revealed significant economic disparities (F = 7.512; p < 0.002), with lower-income groups experiencing higher exposure—a disparity not captured by PurpleAir data (F = 0.756; p < 0.474). These findings highlight the importance of considering both indoor and outdoor air quality to reduce bias in exposure estimates and more accurately represent environmental disparities.