Indoor Pollution Research Articles

Indoor pollution control based on surrogate model for residential buildings

Individuals typically spend most of their lives indoors, predominantly in spaces like offices and residences. Consequently, prolonged indoor exposure underscores the critical significance of maintaining optimal indoor air quality (IAQ) to safeguard one's health. The primary impediment to attaining efficient regulation of Indoor Air Quality (IAQ) is the challenge of monitoring the IAQ parameters, particularly within the immediate vicinity of an individual's breathing space. Current heating, ventilation, and air conditioning systems lack the ability to rapidly predict and optimize the quality of indoor air. The objective of this study is to acquire the distribution features of indoor pollutants and precise indoor environment data in order to efficiently forecast and enhance the IAQ. To achieve this objective, a proposed surrogate model was developed using computational fluid dynamics (CFD). Notably, the Kriging surrogate model can rapidly predict IAQ while using a limited number of CFD runs. CFD are widely used as numerical simulation methods to obtain the accurate information. Surrogate models can rapidly forecast indoor environmental conditions using CFD simulation data simultaneously. Optimization algorithms can efficiently achieve desirable indoor ambient conditions, offering highly effective and intelligent control techniques for indoor atmospheric ventilation.

Ventilation regulations and occupant practices: undetectable pollution and invisible extraction

This sociotechnical investigation examines the use of ventilation systems in homes in London, UK. These homes were built with ventilation systems as described by guidance in the UK Building Regulations Approved Document F. These systems are assumed to provide adequate ventilation rates. However, previous measurements in these homes show that ventilation rates are inadequate. Using social practice theory as a framework to analyse the qualitative data, the intended use of the ventilation systems is compared to participants’ actual practices of manipulating the indoor air, revealing discrepancies between the two. Occupants had limited knowledge of indoor pollutants but were highly motivated to control and interact with the smells and air in their homes. They primarily used technologies that were not part of the planned system, because the latter’s functioning was opaque to occupants and not well connected to their other practices. The highlighted discrepancies in four case study homes between planned and actual ventilation system operation help to identify how future systems could be improved to ensure adequate ventilation rates and good indoor air quality in airtight homes. Policy relevance This research investigates the extent to which the intended operation of domestic ventilation systems set out in Approved Document F to the UK Building Regulations is accomplished in practice. The findings show that ventilation equipment is not used as intended. The research suggests a need for future guidance to more actively consider routes by which occupants can learn how to use and maintain their ventilation systems, and how to identify and remove indoor air pollution. There is a risk of continuing underventilation in homes unless efforts are made to ensure the systems are easily interpretable and robust to a reasonable range of internal conditions and social contexts.

Overview of the Alaskan Layered Pollution and Chemical Analysis (ALPACA) Field Experiment.

The Alaskan Layered Pollution And Chemical Analysis (ALPACA) field experiment was a collaborative study designed to improve understanding of pollution sources and chemical processes during winter (cold climate and low-photochemical activity), to investigate indoor pollution, and to study dispersion of pollution as affected by frequent temperature inversions. A number of the research goals were motivated by questions raised by residents of Fairbanks, Alaska, where the study was held. This paper describes the measurement strategies and the conditions encountered during the January and February 2022 field experiment, and reports early examples of how the measurements addressed research goals, particularly those of interest to the residents. Outdoor air measurements showed high concentrations of particulate matter and pollutant gases including volatile organic carbon species. During pollution events, low winds and extremely stable atmospheric conditions trapped pollution below 73 m, an extremely shallow vertical scale. Tethered-balloon-based measurements intercepted plumes aloft, which were associated with power plant point sources through transport modeling. Because cold climate residents spend much of their time indoors, the study included an indoor air quality component, where measurements were made inside and outside a house to study infiltration and indoor sources. In the absence of indoor activities such as cooking and/or heating with a pellet stove, indoor particulate matter concentrations were lower than outdoors; however, cooking and pellet stove burns often caused higher indoor particulate matter concentrations than outdoors. The mass-normalized particulate matter oxidative potential, a health-relevant property measured here by the reactivity with dithiothreiol, of indoor particles varied by source, with cooking particles having less oxidative potential per mass than pellet stove particles.

Enhancement of Indoor Air Quality with a Displacement Ventilation System Comprising a 4-Way Fan Coil Unit and Multiple Air Purifiers

In indoor spaces without mechanical ventilation systems, a common approach involves using a ceiling-mounted 4-way fan coil unit (4WFCU) to regulate indoor temperature and placing floor-level air purifiers (APs) to remove indoor pollutants. This study introduces a differentiated displacement ventilation system (DVS) that connects multiple APs to the 4WFCU using ductwork. The age of air was compared between the case where the newly designed DVS was implemented and the reference case where 4WFCU and APs operated independently. When there were no obstacles in the office central area, the reference system exhibited a lower age of air. Conversely, when obstacles such as desks and partitions were present in the central area, the proposed DVS was found to improve indoor air quality. The DVS resulted in minimal interference among pathlines of the air discharged from multiple floor-level APs and their efficient suction through the ceiling-mounted 4WFCU and diffusers, significantly reducing stagnant air zones, while pathlines of the air discharged from the 4WFCU and APs interfered significantly when they operated independently, leading to larger stagnant areas in the air distribution. Therefore, modifying office spaces with ceiling-mounted 4WFCUs using the proposed DVS is anticipated to substantially enhance indoor air quality through a straightforward installation process.

Endocrine disrupting potential of total and bioaccessible extracts of dust from seven different types of indoor environment

Information on the indoor environment as a source of exposure with potential adverse health effects is mostly limited to a few pollutant groups and indoor types. This study provides a comprehensive toxicological profile of chemical mixtures associated with dust from various types of indoor environments, namely cars, houses, prefabricated apartments, kindergartens, offices, public spaces, and schools. Organic extracts of two different polarities and bioaccessible extracts mimicking the gastrointestinal conditions were prepared from two different particle size fractions of dust. These extracts were tested on a battery of human cell-based bioassays to assess endocrine disrupting potentials. Furthermore, 155 chemicals from different pollutant groups were measured and their relevance for the bioactivity was determined using concentration addition modelling. The exhaustive and bioaccessible extracts of dust from the different microenvironments interfered with aryl hydrocarbon receptor, estrogen, androgen, glucocorticoid, and thyroid hormone (TH) receptor signalling, and with TH transport. Noteably, bioaccessible extracts from offices and public spaces showed higher estrogenic effects than the organic solvent extracts. 114 of the 155 targeted chemicals were detectable, but the observed bioactivity could be only marginally explained by the detected chemicals. Diverse toxicity patterns across different microenvironments that people inhabit throughout their lifetime indicate potential health and developmental risks, especially for children. Limited data on the endocrine disrupting potency of relevant chemical classes, especially those deployed as replacements for legacy contaminants, requires further study.

Customizing Wettability of Defect-Rich CeO2/TiO2 Nanotube Arrays for Humidity-Resistant, Ultrafast, and Sensitive Ammonia Response.

In all their applications, gas sensors should satisfy several requirements, including low cost, reduced energy consumption, fast response/recovery, high sensitivity, and reliability in a broad humidity range. Unfortunately, the fast response/recovery and sensing reliability under high humidity conditions are often still missing, especially those working at room temperature. In this study, a humidity-resistant gas sensor with an ultrafast response/recovery rate was designed by integrating a defect-rich semiconducting sensing interface and a self-assembled monolayer (SAM) with controllable wettability. As a proof-of-concept application, ammonia (NH3), one of the atmospheric and indoor pollutants, was selected as the target gas. The decoration of interconnected defective CeO2 nanowires on spaced TiO2 nanotube arrays (NTAs) provided superior NH3 sensing performances. Moreover, we showed that manipulating the functional end group of SAMs is an efficient and simple method to adjust the wettability, by which 86% sensitivity retention with an ultrafast response (within 5 s) and a low limit of detection (45 ppb) were achieved even at 75% relative humidity and room temperature. This work provides a new route toward the comprehensive design and application of metal oxide semiconductors for trace gas monitoring under harsh conditions, such as those of agricultural, environmental, and industrial fields.

Indoor air pollution: an Italian Knowledge, Attitude and Practice (KAP) study among the general population.

Indoor air pollution negatively affects population health and the national health services in terms of socio-economic costs. The presence of indoor pollutants depends a lot on lifestyles. The aim of this work is to evaluate knowledge, daily habits and the preventive behaviors in order to contrast the effects on health caused by indoor pollutants. The study was conducted through the administration of questionnaires to the population resident in the metropolitan city of Messina (Italy), asking about sociodemographic characteristics, knowledge, daily habits and preventive behaviors. The questionnaire was filled by 894 subjects (46.8% M; 53.2% F). Regarding knowledge, 66.8% had heard of indoor air pollution and 94.9% knew what the most common indoor pollutants are; regarding daily habits they often aired out the house (91.9% in the morning and 71.4% after cleaning), 24.8% were smokers and 36.7 of them smoked indoors; regarding preventive behaviors, 41.6% chose the cleaning products based on habit and only 32.9% bought plants able to purify environments. Although the analyzed population had adequate knowledge of indoor air pollution, this did not strongly impact on the adoption of healthy lifestyles. Therefore, it becomes necessary to intervene on a social level with environmental education activities, starting from school age.

Wildfires exacerbate inequalities in indoor pollution exposure

Wildfires lead to dramatic increases in fine particulate matter pollution concentrations. Based on the premise that higher-income households purchase more defensive investments to reduce the degree to which outdoor pollution infiltrates indoors, in this study, we investigate how income contributes to outdoor–indoor pollution infiltration rates during wildfire events. Using crowd-sourced data from the PurpleAir Real-Time Air Quality Monitoring Network and econometric models that explore variations in monitor readings over time, we find increases in outdoor pollution lead to significant increases in indoor pollution, but disproportionately so in lower-income areas. The results highlight a new inequality in pollution exposure: not only are outdoor pollution levels higher for lower-income individuals, but indoor pollution levels are higher even for similar outdoor pollution levels.

The application analysis of the eco-interior concept to My Dormy Hostel UMM as an effort to achieve environmental sustainability

Public awareness about environmental sustainability is increasing. Various approaches are being taken to address environmental issues, including in the field of interior design. One of the approaches that highlight environmental awareness and sustainability is known as eco-interior. My Dormy Hostel UMM is a pioneering hostel in Malang that utilizes repurposed containers as its primary building material. This study aims to observe the application of the eco-interior concept at My Dormy Hostel UMM, with diagnostic evaluation analysis based on the concept of eco-interior. The eco-interior concept is divided into four levels of classification: ideal situation, substantial and mild effort, and general application. The finding shows that falls under the third level of the eco-interior concept, “substantial effort”. The application of the concept is commendable but not yet considered ideal or optimal. Specifically, the ventilation system meets the standards for an ideal situation, while the space organization, material selection, and lighting systems meet the criteria for a substantial effort. Electromagnetic emissions only reach the level of mild effort, whereas water sanitation, indoor pollution, and indoor waste management are categorized as general applications. This research is expected to be a reference for evaluating the application of the eco-interior concept in the hospitality industry.

Potential Pollutants and Indoor Air Quality Variables Association towards Implementation of the Breathing Architecture Concept: A Review

Indoor air quality is essential in improving indoor well-being since most people spend their time there. The breathing Architecture concept promotes a strategy for designing indoor space to maintain the indoor air quality. This concept has various challenges, such as indoor pollutants determining the indoor environment to be healthy and decent. This study aims to identify the relationship between IAQ variables related to Breathing Architecture and air pollutants based on secondary sources of past and existing research ten years ago. The review identified 16 articles collected by selecting several relevant keywords in ScienceDirect and screening the title and abstract. Content analysis was conducted to analyze the relationship between IAQ variables and pollutants and their potential association with the breathing architecture concept. The results show that air exchange rate, volume of spaces, relative humidity, and indoor-outdoor temperature are the most potential variables and have a possible relationship while implementing the BA concept. Using these variables, the optimal condition might be perceived since the possibility of lower pollutant contamination might be lower, and the purpose of breathing architecture might be obtained. However, the relationship between other variables and pollutants requires future studies since it is undescribed or may impact other variables.

Nicotiana alkaloids-intervened phospholipid ozonolysis at the air-water interface

Cigarette nicotiana alkaloids associated with lung and cardiovascular diseases attack enormous attention. However, the mechanism at the molecular level between nicotiana alkaloids and phospholipid ozonolysis remains elusive. Herein, we investigated the interfacial ozonolysis of a hung droplet containing 1-palmitoyl-2-oleoyl-sn-phosphatidylglycerol (POPG) intervened by nicotiana alkaloids (4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, NNK; rac-N′-nitrosonornicotine, NNN; nicotine; and (R,S)-N-nitrosoanasabine, NAT) and followed by on-line mass spectrometry analysis. NNK and NNN showed an acceleration on the interfacial ozonolysis, while nicotine and NAT inhibited this chemistry. Such acceleration/inhibition on POPG ozonolysis was positively correlated with nicotiana alkaloid concentrations. The reaction rate constants suggested that the ozonolysis of lung phospholipids exposed to cigarette smoke at the air-water interface occurred rapidly. A possible mechanism of the hydrophilic/oleophilic nature of nicotiana alkaloids mediating the packing density of POPG was proposed. NNK and NNN with a hydrophilic nature inserted into the POPG monolayer loosed the packing, but nicotine and NAT with an oleophilic nature let the POPG closely pack and shield the CC double bonds exposed to ozone (O3). These results gain the knowledge of nicotiana alkaloids mediated phospholipid ozonolysis at the molecule level and provide a method for online interfacial reaction studies associated with elevated indoor pollutants on public health.

Indoor air pollution and cognitive function among older adults in India: a multiple mediation approach through depression and sleep disorders

BackgroundStudies across multiple countries reveal that depression and sleep disorders can lead to cognitive decline. This study aims to speculate on the effect of different sources of indoor air pollution on cognition and to explore the mediation effect of depression and sleep disorders on cognition when exposed to indoor air pollution. We hypothesize that an older adult experiences higher cognitive decline from indoor pollution when mediated by depression and sleep disorders.MethodsWe use data from Longitudinal Aging Study in India (LASI), 2017–2018, and employ a multiple mediation model to understand the relationship between indoor air pollution and cognition through sleep disorders and depression while adjusting for possible confounders. Sensitivity analysis was applied to see the effect of different sources of indoor pollution (cooking fuel, indoor smoke products, and secondhand smoke) on cognitive performance.ResultsThe effect of three sources of indoor pollutants on cognition increased when combined, indicating stronger cognitive decline. Unclean cooking practices, indoor smoke (from incense sticks and mosquito coils), and secondhand smoke were strongly associated with sleep disorders and depression among older adults. Indoor air pollution was negatively associated with cognitive health (β= -0.38) while positively associated with depression (β= 0.18) and sleep disorders (β= 0.038) acting as mediators. Sensitivity analysis explained 45% variability while adjusting for confounders.ConclusionThe study lays a foundation for future investigations into the nexus of indoor pollution and mental health. It is essential to formulate policies to reduce exposure to varying sources of indoor air pollutants and improve screening for mental health services as a public health priority.

Particle size, carbon composition and sources of indoor dust in Nanchang, China

Indoor dust is an enriched environmental media for lots of chemical pollutants, while indoor pollutants pose high exposure level and health risks to humans. In this work, indoor dust samples from four types of indoor environments (residence near steel plant, residence near road, student dormitory and rural kitchen) in Nanchang city were collected and their particle sizes and carbon components were analyzed. The sources of carbon components were traced based on the distribution of carbon components and the correlation between the components. The particle size distribution mainly presents a bimodal mode (0.1–3 and 10–40 μm size intervals, accounting for 8.9% and 7.4%). The average OC and EC in the as-collected indoor dust samples were 34.1 and 52.7 mg/g for residences around the steel plant, 43.9 and 41.4 mg/g for residences adjacent to the road, 119.3 and 66.4 mg/g for students' dormitories, 73.5 and 49.8 mg/g for rural kitchens, respectively. A strong correlation between OC and Char was observed, indicating strong homology between the sources of the two components. In addition, the correlation between two of EC1, OC2, and OC3 (OC2 and OC3 are fractions of OC and EC1 is a fraction of EC) were significant, indicating a large contribution of motor vehicle exhaust to indoor dust. The average ratios of OC/EC and Char/Soot suggest the contribution of automobile exhaust, indoor smoking and biomass combustion to indoor dust. The results of this work provide a scientific, convenient, and reliable approach to explore the source of particulate matter indoors based on the distribution of carbon components.

Formaldehyde degradation using Biofilter loaded with Compost, Vermiculite and Activated Carbon: Performance and Optimization

<p>Formaldehyde is one of the typical indoor pollutants causing theprevalence of acute health issues among those residing in indoor environments. Biofiltrationis a commonly adopted technique to treat indoor air pollutants. In this investigation, a biofilter was fabricated and compactly filled with compost, vermiculite and activated carbon (65:25:10) as a media composition for enhanced formaldehyde degradation. The influence of formaldehyde inlet concentration (0.01 – 1 gm-3g/m3) and EBRT (30 – 180 s) was studied to evaluate the biofilter performance. Their progression was assessed with dynamic operations in five phases with two stages each. The formaldehyde removal was achieved between the range of 32% to 98% with regular intervals of EBRT at 30, 60, 90, 120, 150 and 180 seconds, which depend upon varying their flow rate and inlet loading rate. The biofilter performance lasted for over 202 days with a 98% formaldehyde removal and 23 g/m3h-1biofilter capacity under the maximum EBRT (180 s) and inlet formaldehyde concentration (1 gm-3g/m3). The experimental findings demonstrated the efficacy of biofilter in withstanding substantial formaldehyde loading rate while maintaining an acceptable EBRT. The primary microbe responsible for formaldehyde degradation was identified to be as gram-negative bacteria.</p>

Air Pollution: A Challenge to Public Health and Healthcare Systems

Air Pollution: A Challenge to Public Health and Healthcare Systems

Organic toxicants and emerging contaminants in hospital interiors before and during the SARS-CoV2 pandemic: alkanes and PAHs.

Indoor pollution and deposition dust (DD), in particular, are acquiring concern, due to long exposure time and importance of intake by humans through contact and ingestion. Hospitals look a special category of sites, owing to peculiar contaminants affecting them and to presence of people prone to adverse effects induced by toxicants. Four in-field campaigns aimed at understanding the chemical composition of DD were performed in five Italian hospitals. Measurements were performed before (autumn 2019), during (spring 2021), and after (winter 2022) the peak of SARS-CoV2 and when restrictions caused by pandemic were revoked (winter 2023). Parallel measurements were made outdoors (2022), as well as in a university and a dwelling. Targeted contaminants were n-alkanes and polycyclic aromatic hydrocarbons (PAHs), while iso- and anteiso-alkanes were analyzed to assess the impact of tobacco smoking. Total n-alkanes ranged from 3.9 ± 2.3 to 20.5 ± 4.2mg/g, with higher percentages of short chain homologs in 2019. PAHs ranged from 0.24 ± 0.22 to 0.83 ± 0.50mg/g, with light congeners (≤ 228 a.m.u.) always exceeding the heavy ones (≥ 252 a.m.u.). According to carbon preference indexes, alkanes originated overall from anthropogenic sources. Microorganisms resulted to affect a hospital, and tobacco smoke accounted for ~ 4-20‰ of DD mass. As for PAH sources, the diagnostic concentration ratios suggested the concourse of biological matter burning and vehicle emission. Benzo[a]pyrene equivalent carcinogenic and mutagenic potencies of depositions at hospitals ranged ~ 9-39μg/g and ~ 15-76μg/g, respectively, which seems of concern for health. DD composition in hospitals was different from that outside the premises, as well as that found at university and at dwelling.

Modeling a Smart IoT Device for Monitoring Indoor and Outdoor Atmospheric Pollution

Air pollution is caused by chemical, physical, or biological components alters the fundamental properties of the atmosphere, and contaminates the interior or outdoor settings. With the rapid industrialization activity in recent years, there is an urgent need to monitor air quality. The proposed research provides a mechanism for monitoring air pollution in indoor and outdoor environments. The system consists of an IoT-based Arduino device. The Arduino IDE connects the Temperature and Humidity sensor, Grove light sensor, and air quality sensor to measure the air pollutants such as Carbon dioxide CO2, Nitrogen oxide (NOx), and Particulate Matter PM2.5. The sensors work efficiently and provide qualitative findings from the environment when they are exposed to CO2, gasoline, solvents, thinner, formaldehyde, and other harmful chemicals. The Wi-Fi module of the Blues Wireless Notehub is used for secure data routing to the IoT cloud. The Air Quality Index (AQI) measures provide information on whether there is something unsafe in indoor and outdoor environments. For collecting and analyzing the device data, the Notecard is intended to be used with a cloud storage service. Also, the indoor fire detector identifies the incident of fire intimates the users through the alarm, and measures the indoor pollutant at that time. The proposed smart IoT product model would be an excellent device for air quality monitoring because of its long-term consistency and low electricity consumption.

Air change per hour improvement for positive and negative pressure mechanical ventilation facilities systems

Ventilation reduces indoor pollutants, and this issue has recently received attention. Most scholars adopt ventilation strategies to reduce energy consumption. While natural ventilation does not require ventilation facilities, it also brings many challenges, such as lack of external openings and insufficient air change per hour. Therefore, it is necessary to rely on mechanical ventilation to increase indoor air change per hour. However, mechanical ventilation comes with increased energy consumption, which poses a significant challenge to reducing energy usage at present.To improve energy usage, increase air changes per hour, and reduce the number of fans by half, we propose implementing positive and negative pressure ventilation indoors at the same airflow rate (3000 CMH). The research results showed that positive and negative pressure ventilation increased air changes per hour by 94 % and 62 %, respectively, while also reducing fan energy usage by 50 %. Through visualization, we also discovered the uneven distribution of indoor carbon dioxide levels. This breakthrough is of significant importance for current indoor mechanical ventilation systems and contributes greatly to future near-zero carbon emissions.

Indoor Air Pollution: A Review on the Challenges in Third World Countries

Background: The challenges of third-world countries toward curbing indoor air pollution seem insurmountable as its solution is closely linked to their economic incapacities, lifestyle, and existing outdoor air quality. The economic incapacities include types of the cookstove, fuel sources, types of insecticides and pesticides, building patterns, indoor fermentation activities (such as leaving dirty plates and biological waste in the house for a long time), and regulation on the use of deodorants. Aside from the common pollutants from these sources, the reactive chemistry of pollutants leads to other kinds of pollutants which have been reported to be short-lived but dangerous. Objectives: The objectives of the study are to: profile emerging indoor pollutants; examine the pollutant dynamics and their impact on unplanned regions of developing countries; offer solutions to curb indoor pollution in the identified region; elaborate on the cost analysis of existing solutions and how irrelevant they may be due to the rising poverty index; and project how government policies could help in reducing indoor pollution. Design: This paper is a review that wholistically examined indoor pollution. A total of fifty-six articles was reviewed in addition to the data obtained from MERRA-2. Results: The study observed that indoor air pollution dynamics are more complex—compared to outdoor air pollution. It was observed that the possibility to control indoor air pollution is based on the type of pollutants, the reactive chemistry of the pollutants, and ventilation in the building. This review shows that poverty is one of the many reasons why indoor air pollution would be a source of menace for a long time in third-world countries. Several solutions to curbing indoor air pollution were considered with a principal focus on cost and availability. Limitations: Most experimental results that were used to corroborate postulates were obtained from the literature. The accuracy of those experiments and the sensitivity of the equipment used cannot be verified. Conclusion: The plant-based technique was identified as a perfect solution to indoor air pollution control in third-world countries but the local architecture and lifestyle of most third-world countries constitute a threat to its adoption. It was observed that less than 8% of third-world countries have specific Air Quality Acts which have not been amended for decades. Most third-world countries have a general Environmental Act with air quality as a sub-section in the Act with very low fines for violators. The inclusion of indoor air quality as a vital public health issue in third-world countries is necessary for the preservation of lives and posterity.

Indoor cooking and cleaning as a source of outdoor air pollution in urban environments.

Indoor sources of air pollution, such as from cooking and cleaning, play a key role in indoor gas-phase chemistry. The focus of the impact of these activities on air quality tends to be indoors, with less attention given to the impact on air quality outside buildings. This study uses the INdoor CHEmical Model in Python (INCHEM-Py) and the Advanced Dispersion Modelling System (ADMS) to quantify the impact cooking and cleaning have on indoor and outdoor air quality for an idealised street of houses. INCHEM-Py has been developed to determine the concentrations of 106 indoor volatile organic compounds at the point they leave a building (defined as near-field concentrations). For a simulated 140 m long street with 10 equi-distant houses undertaking cooking and cleaning activities, the maximum downwind concentration of acetaldehyde increases from a background value of 0.1 ppb to 0.9 ppb post-cooking, whilst the maximum downwind chloroform concentrations increase from 1.2 to 6.2 ppt after cleaning. Although emissions to outdoors are higher when cooking and cleaning happen indoors, the contribution of these activities to total UK emissions of volatile organic compounds is low (less than 1%), and comprise about a quarter of those emitted from traffic across the UK. It is important to quantify these emissions, particularly as continued vehicle technology improvements lead to lower direct emissions outdoors, making indoor emissions relatively more important. Understanding how indoor pollution can affect outdoor environments, will allow better mitigation measures to be designed in the future that can take into account all sources of pollution that contribute to human exposure.