Air quality perception of pedestrians in an urban outdoor Mediterranean environment: A field survey approach

The perception of air pollution and its health risk: a scoping review of measures and methods

BACKGROUND

Although there is increasing awareness of the health risks of air pollution as a global issue, few studies have focused on the methods for assessing individuals' perceptions of these risks. This scoping review aimed to identify previous research evaluating individuals' perceptions of air pollution and its health effects, and to explore the measurement of perceptions, as a key resource for health behaviour.

METHODS

The review followed the methodological framework proposed by Arksey and O'Malley. PubMed and Web of Science were searched. After initial and full-text screening, we further selected studies with standardised scales that had previously been tested for reliability and validity in assessing awareness and perceptions.

RESULTS

After full-text screening, 95 studies were identified. 'Perception/awareness of air quality' was often measured, as well as 'Perception of health risk.' Only nine studies (9.5%) used validated scaled questionnaires. There was considerable variation in the scales used to measure the multiple dimensions of risk perception for air pollution.

CONCLUSION

Few studies used structured scales to quantify individuals' perceptions, limiting comparisons among studies. Standardised methods for measuring health risk perception are needed.

Assessment of air pollution and air quality perception mismatch using mobility-based real-time exposure

Air pollution poses a threat to human health. Public perceptions of air pollution are important for individual self-protection and policy-making. Given the uncertainty faced by residence-based exposure (RB) measurements, this study measures individuals' real-time mobility-based (MB) exposures and perceptions of air pollution by considering people's daily movement. It explores how contextual uncertainties may influence the disparities in perceived air quality by taking into account RB and MB environmental factors. In addition, we explore factors that are related to the mismatch between people's perceived air quality and actual air pollution exposure. Using K-means clustering to divide the PM2.5 values into two groups, a mismatch happens when the perceived air quality is poor but the air pollution level is lower than 15.536μg/m3 and when the perceived air quality is good but the air pollution level is higher than 15.608μg/m3. The results show that there is a mismatch between air pollution exposure and perception of air pollution. People with low income are exposed to higher air pollution. Unemployed people and people with more serious mental health symptoms (e.g., depression) have a higher chance of accurately assessing air pollution (e.g., perceiving air quality as poor when air pollution levels are high). Older people and those with a higher MB open space density tend to underestimate air pollution. Students tend to perceive air quality as good. People who are surrounded by higher MB transportation land-use density and green space density tend to perceive air quality as poor. The results can help policymakers to increase public awareness of high air pollution areas, and consider the health effects of landscapes during planning.

Does the air pollution level information matter in public perception? Insights from China

Evidence from the past has previously established that the air information disclosure program has an impact on people's air pollution perception. However, the influence of the concrete information communicated has always been overlooked. In this study, we examine the impact of the announced air pollution level information on public pollution perception. We collect air-related Weibo posts from June 1, 2019, to May 31, 2021, in China, and apply a regression discontinuity (RD) design to quantify the impact. According to our research, when a higher pollution level is announced, people's pollution perception expressed online rises by 3.5%-3.7%, which is approximately equivalent to the response to a more than 100 Air Quality Index (AQI) increase. The episode-based analyses reveal that the impact of pollution level information would fade away along with the persistence or the frequency of the announced pollution episode, which shows a phenomenon of information fatigue. The heterogeneity analyses reveal that the impact of pollution level is significant only when the original pollution level is "Good" or "Lightly Polluted", leading to an increase of pollution perception by 2.8% and 4.8%, respectively. We also find that men, highly-educated, and urban residents are more responsive to the pollution level information. Our study illustrates a detailed picture of how people's perception responds to the announced pollution level information under the AQI standards, and can provide guidance for policymakers when developing the AQI standards to maximize the welfare of the air information.

Air Quality, Pollution Perception, and Residents' Health: Evidence from China

Environmental and resident health issues associated with air pollution are an area of growing concern for both policy officials and the general public. In recent years, China has been accelerating the construction of a Beautiful China and a Healthy China, with the aim of protecting and improving the environment and ensuring public health. In this study, we aimed to explore the impact of air quality and air pollution perception on residents' health. This study used the 2017 Chinese General Social Survey data to measure self-rated health, mental health, and air pollution perception. Using matched socioeconomic indicators and air pollution data, we analyzed the relationship between subjective perception of air pollution, objective air pollution data, and residents' health. The results showed the following: (1) Air pollution perception has a significant negative impact on self-rated health and mental health. Thus, it needs more consideration to reduce environmental health risks. (2) Objective air pollution has a significant negative impact on mental health. At the same time, its effect on self-rated health was insignificant. These results provide empirical evidence supporting the Chinese government's decision to invest more in combating air pollution and ensuring the health of Chinese residents.

Computer Vision Technology for Monitoring of Indoor and Outdoor Environments and HVAC Equipment: A Review

Artificial intelligence technologies such as computer vision (CV), machine learning, Internet of Things (IoT), and robotics have advanced rapidly in recent years. The new technologies provide non-contact measurements in three areas: indoor environmental monitoring, outdoor environ-mental monitoring, and equipment monitoring. This paper summarizes the specific applications of non-contact measurement based on infrared images and visible images in the areas of personnel skin temperature, position posture, the urban physical environment, building construction safety, and equipment operation status. At the same time, the challenges and opportunities associated with the application of CV technology are anticipated.

Inconsistent Association between Perceived Air Quality and Self-Reported Respiratory Symptoms: A Pilot Study and Implications for Environmental Health Studies

As public awareness of air quality issues becomes heightened, people's perception of air quality is drawing increasing academic interest. However, data about people's perceived environment need scrutiny before being used in environmental health studies. In this research, we examine the associations between people's perceptions of air quality and their self-reported respiratory health symptoms. Spearman rank correlation coefficients were estimated and the associations were tested at the 95% confidence level. Using data collected from participants in two representative communities in Hong Kong, the results indicate a weak but significant association between people's perceived air quality and their self-reported frequency of respiratory symptoms. However, there are disparities in such an association between different genders, age groups, household income levels, education levels, marital statuses, and geographic contexts. The most striking disparities are between genders and geographic contexts. Multiple significant associations were observed for male participants (correlation coefficients: 0.169~0.205, p-values: 0.021~0.049), while none was observed for female participants. Besides, multiple significant associations were observed in the old town (correlation coefficients: 0.164~0.270, p-values: 0.003~0.048), while none was observed in the new town. The results have significant implications for environmental health research using social media data, whose reliability depends on the association between people's perceived or actual environments and their health outcomes. Since inconsistent associations exist between different groups of people, researchers need to scrutinize social media data before using them in health studies.

Concentration-dependent increase in symptoms due to diesel exhaust in a controlled human exposure study

Background

Traffic-related air pollution (TRAP) exposure causes adverse effects on wellbeing and quality of life, which can be studied non-invasively using self-reported symptoms. However, little is known about the effects of different TRAP concentrations on symptoms following controlled exposures, where acute responses can be studied with limited confounding. We investigated the concentration–response relationship between diesel exhaust (DE) exposure, as a model TRAP, and self-reported symptoms.

Methods

We recruited 17 healthy non-smokers into a double-blind crossover study where they were exposed to filtered air (FA) and DE standardized to 20, 50, 150 µg/m3 PM2.5 for 4 h, with a ≥ 4-week washout between exposures. Immediately before, and at 4 h and 24 h from the beginning of the exposure, we administered visual analog scale (VAS) questionnaires and grouped responses into chest, constitutional, eye, neurological, and nasal categories. Additionally, we assessed how the symptom response was related to exposure perception and airway function.

Results

An increase in DE concentration raised total (β ± standard error = 0.05 ± 0.03, P = 0.04), constitutional (0.01 ± 0.01, P = 0.03) and eye (0.02 ± 0.01, P = 0.05) symptoms at 4 h, modified by perception of temperature, noise, and anxiety. These symptoms were also correlated with airway inflammation. Compared to FA, symptoms were significantly increased at 150 µg/m3 for the total (8.45 ± 3.92, P = 0.04) and eye (3.18 ± 1.55, P = 0.05) categories, with trends towards higher values in the constitutional (1.49 ± 0.86, P = 0.09) and nasal (1.71 ± 0.96, P = 0.08) categories.

Conclusion

DE exposure induced a concentration-dependent increase in symptoms, primarily in the eyes and body, that was modified by environmental perception. These observations emphasize the inflammatory and sensory effects of TRAP, with a potential threshold below 150 µg/m3 PM2.5. We demonstrate VAS questionnaires as a useful tool for health monitoring and provide insight into the TRAP concentration–response at exposure levels relevant to public health policy.

Citizens' Perception on Air Quality in Portugal-How Concern Motivates Awareness

This study aimed to understand the knowledge of Portuguese citizens about air quality and the extent to which the concerns about specific environmental problems can motivate their acquaintance of information. Moreover, this study also allowed to understand which information about air quality needs further dissemination to provide the citizens with all the available tools and the correct knowledge. For this, a national online survey about air quality perception was conducted, where 1131 answers were obtained and two different populations were compared: the general population and a sub-population from an urban-industrial area of Lisbon metropolitan area that had experienced frequent air pollution events in the past. Air pollution was considered the environmental topic of higher concern among this sub-population (61.4%), while in the general population it ranked thirdly (27.4%). Generally, the sub-population showed higher knowledge about air quality than the general population, with 61% being able to identify at least one air pollutant. The perception of the local air quality was also very different between populations, with 61% of the sub-population considering it poor or very poor, while only 14% of the general population had the same perception, which highlights the different levels of concern between populations. A weak knowledge about air pollutants (50% of the general population could not identify any air pollutant) and an erroneous perception of the contribution of the different pollution sources to air quality levels were found. More than 50% of the respondents of both populations were considered to not have enough information regarding the air quality in their area of residence, with the national air quality database being unknown to almost everyone. Overall, strong efforts should be made to increase the awareness about the importance of air quality, which may promote a higher acceptance of the implementation of future actions to improve air quality.

Multi-domain human-oriented approach to evaluate human comfort in outdoor environments

Human comfort outdoors is widely investigated, but most studies explore the comfort domains singularly. This paper aimed to evaluate human comfort in parks, verifying the importance of using a multi-domain (simultaneously evaluating thermal, visual, acoustic, and air quality) and multi-disciplinary (combining environmental and social fields) approach. A walk through a pre-defined path from one park to another was repeated twice per day on four consecutive days in June, with three participants per walk. The two investigated parks are in central Italy and were chosen because they differ in their design and spatial characteristics. Environmental data were recorded with an innovative wearable device during the whole walk, and surveys were used to assess people's perceptions of the parks. Despite observed differences in collected physical parameters, the survey's responses were similar, and different comfort domains showed dependence on each other in the two parks. Logistic regression models were developed for each park, and they revealed that the qualitative information predicted the overall comfort level more accurately than the environmental data. In detail, the models based on environmental data resulted in R² equal to 0.126 and 0.111 in Parks 1 and 2, respectively, whereas using the survey answers increased it up to 0.820 (Park 1) and 0.806 (Park 2). This study contributes to addressing the gap in multi-domain comfort studies outdoors and confirms the importance of using multi-disciplinary and multi-domain approaches for a complete comfort analysis, supporting holistic human-biometeorology-oriented models and forecasting opportunities that can promote improvements in urban environmental quality and liveability.

Spatialized Analysis of Air Pollution Complaints in Beijing Using the BERT+CRF Model

(1) Background: To better carry out air pollution control and to assist in accurate investigations of air pollution, in this study, we fully explore the spatial distribution characteristics of air pollution complaint results and provide guidance for air pollution control by combining regional air monitoring data. (2) Methods: By selecting the air pollution complaint information in Beijing from 2019 to 2020, in this study, we extract the names and addresses of complaint points, as well as the complaint times and types by adopting the BERT (bidirectional encoder representations from transformers) + CRF (conditional random field) model deep learning method. Moreover, through further filtering and processing of the complaint points’ address information, we achieve address matching and spatial positioning of the complaint points, and realize the regional spatial representation of air pollution complaints in Beijing in the form of a heat map. (3) Results: The experimental results are compared and analyzed with the ranking data of total suspended particulate (TSP) concentration of townships (streets) in Beijing during the same period, indicating that the key areas of air pollution complaints have a high correlation with the key polluted township (street) areas. The distribution of complaints and the types of complaints in each township (street) differ according to the population density in each township (street), the level of education, and economic activity. (4) Conclusions: The results of this study show that the public, as the intuitive perceiver of air pollution, is sensitive to the air pollution situation at a smaller spatial scale; furthermore, complaints can provide guidance and reference for the direction of air pollution control and law enforcement investigations when coupled with geographical features and economic status.

Study on the Influence of Globe Thermometer Method on the Accuracy of Calculating Outdoor Mean Radiant Temperature and Thermal Comfort

With global warming and the rapid development of urbanization, the outdoor thermal environment is deteriorating. More and more research focuses on the outdoor thermal environment and thermal comfort. The globe thermometer method is widely used in more than half of the outdoor thermal environment research studies, but there is a large error compared with the six-direction method. In order to explore the accuracy of the results of the globe thermometer method and its impact on the subsequent thermal comfort indicators, this study carried out a year-round comparative experiment under multiple working conditions outdoors in cold areas to explore the impact of meteorological parameters such as shortwave radiation, wind speed, and wind direction on the results of the globe thermometer method. The results show that the continuous increase of shortwave radiation reduces the accuracy of the black bulb thermometer to less than 60%, and the instantaneous change of wind speed will make the deviation of the mean radiation temperature obtained by the globe thermometer method exceed 5 °C. The influence of the mean radiation temperature obtained by the globe thermometer method on the thermal comfort index is mainly reflected in the working condition of a high temperature and strong radiation in summer. Taking the six-direction method as the standard, this study gives the scope of application of the globe thermometer method; and taking the human body calculation model of PET as an example, a universal optimization method for detailed division of radiation heat transfer calculation is proposed, so that it can get more accurate and rigorous conclusions in the evaluation of outdoor complex radiation environment.

A New Wearable System for Sensing Outdoor Environmental Conditions for Monitoring Hyper-Microclimate

The rapid urbanization process brings consequences to urban environments, such poor air quality and the urban heat island issues. Due to these effects, environmental monitoring is gaining attention with the aim of identifying local risks and improving cities’ liveability and resilience. However, these environments are very heterogeneous, and high-spatial-resolution data are needed to identify the intra-urban variations of physical parameters. Recently, wearable sensing techniques have been used to perform microscale monitoring, but they usually focus on one environmental physics domain. This paper presents a new wearable system developed to monitor key multidomain parameters related to the air quality, thermal, and visual domains, on a hyperlocal scale from a pedestrian’s perspective. The system consisted of a set of sensors connected to a control unit settled on a backpack and could be connected via Wi-Fi to any portable equipment. The device was prototyped to guarantee the easy sensors maintenance, and a user-friendly dashboard facilitated a real-time monitoring overview. Several tests were conducted to confirm the reliability of the sensors. The new device will allow comprehensive environmental monitoring and multidomain comfort investigations to be carried out, which can support urban planners to face the negative effects of urbanization and to crowd data sourcing in smart cities.

Assessing local heat stress and air quality with the use of remote sensing and pedestrian perception in urban microclimate simulations

Cities are increasingly confronted with multiple environmental and climatic stressors. Especially during heatwaves, street canyons are both producers and sufferers of air pollution and urban heat island (UHI) effects, with severe risks on public health. To better design mitigation measures, it is important to consider both the microclimate behaviors as well as the perceptions of the local population. Therefore, this study examined pedestrian perceptions and microclimate modelings to understand outdoor thermal comfort conditions and air pollution dispersion in the case study neighborhood of Dortmund Marten, Germany. A field survey with measurement points at two street canyons for climatic variables and questionnaires on subjective thermal comfort and air pollution was conducted on a hot day during the heatwave period in August 2020. As a cost-effective method for modeling input generation, we extracted spatial and spectral data like albedo, roof materials and tree locations out of remote sensing imageries. Finally, we compared the modeling results of the physiological equivalent temperature (PET) index, particulate matter concentrations and air temperatures with empirical field measurement data and the questionnaire responses. Results indicate that during hot summer days with light winds from the east, the north-south orientated street canyon with tree arrangements tends to act as a tunnel for particulate matter accumulation. Coincidently, pedestrians show less thermal discomfort than calculated PET values in that particular area during morning and daytime, which underlines the dichotomy of such places. On the other hand, the low rise east-west orientated street canyon shows higher PET votes than predicted by the model. However, particulate matter concentrations were considerably underestimated by the model, while air temperature predictions provided meaningful results. The proposed workflow shows the potential to accelerate future preparations of input data for microclimate modelings, while the results can enhance wind-sensitive planning procedures and heat stress resilience in mid-latitude urban neighborhoods.

The Impact of an Authoritarian Personality on Pro-Environmental Behaviour for Air Pollution Mitigation through Interactions with Social Norms

This study examines how risk perception and authoritarian personality affect public engagement in mitigating air pollution. Data were collected (n = 2010) from 13 Chinese cities with varying air pollution gradients using questionnaires. The results demonstrated that air pollution was significantly correlated with people’s risk perception and concern about air pollution, which significantly affected their pro-environmental behaviour (PEB). However, high-risk perceptions undermine the public’s self-efficacy and reduce people’s PEB in the private sphere. People with high scores of the authoritarian personality type were reluctant to engage in PEB in the private sphere; interestingly, it can also be transformed into a stronger PEB in the public sphere via social norms. Thus, this study suggests that educational activities can break the negative link between authoritarianism and environmentalism, leading to behavioural change. Hence, it is essential for education programs to harvest positive outcomes via adaptive approaches for varying authoritarian personalities.

Indoor air quality investigation of a badminton hall in humid season through objective and subjective approaches

This study investigated the indoor air quality (IAQ) during humid season in an old badminton hall, to explore the IAQ characteristics of natural ventilated sports buildings for public use. The indoor air parameters (temperature, relative humidity and air velocity) and indoor air pollutants (CO₂, TVOC, PM_2.5 and PM₁₀) were measured. A subjective approach was carried out through questionnaire survey. 185 valid questionnaires were recovered, and 68.7% of the participants had exercised. Results show that the indoor air qualities obtained through objective and subjective approaches were obviously different. Indoor PM, TVOC and CO₂ concentrations were normal, but 37.3% of the participants complained about the building materials' smell and 73.5% of the participants reported obvious sweaty odor. Physical activity might reduce a person's sensitivity to the environment. The participants generally felt warm and hot because of the high relative humidity. Post-exercise participants felt significantly hotter than those who did not exercise, and were generally more receptive to IAQ. The method of Fanger was employed to narrow the gap between subjective and objective approaches with a modified parameter, and to furtherly estimate the ventilation. The present study demonstrates the necessity to combine two approaches together to assess the IAQ in sports buildings.

Risk Perception of Air Pollution: A Systematic Review Focused on Particulate Matter Exposure

The adverse health effects of exposure to air pollutants, notably to particulate matter (PM), are well-known, as well as the association with measured or estimated concentration levels. The role of perception can be relevant in exploring effects and pollution control actions. The purpose of this study was to explore studies that analyse people's perception, together with the measurement of air pollution, in order to elucidate the relationship between them. We conducted a systematic review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. In March 2020, PubMed, EMBASE, and Scopus databases were explored in an attempt to search for studies published from 2000 to 2020. The review included 38 studies, most of which were conducted in China (n = 13) and the United States (n = 11) and published over the last four years (n = 26). Three studies were multicenter investigations, while five articles were based on a national-level survey. The air quality (AQ) was assessed by monitoring stations (n = 24) or dispersion models (n = 7). Many studies were population questionnaire-based, air monitoring and time-series studies, and web-based investigations. A direct association between exposure and perception emerged in 20 studies. This systematic review has shown that most of the studies establish a relationship between risk perception measurement. A broad spectrum of concepts and notions related to perception also emerged, which is undoubtedly an indicator of the wealth of available knowledge and is promising for future research.

Associations between individual perceptions of PM2.5 pollution and pulmonary function in Chinese middle-aged and elderly residents

Background

PM_2.5 pollution has become a major public health concern in urban China. Understanding the residents’ individual perceptions toward haze pollution is critical for policymaking and risk communication. However, the perceptions of middle-aged and elderly residents, who particularly vulnerable to haze pollution, are poorly understood. In this study, we aimed to explore their risk perceptions of haze pollution and investigate its relationship with health status and pulmonary function parameters.

Methods

A cross-sectional study of 400 randomly sampled individuals (aged 40 to 90 years) was conducted in Wuxi, a typical PM_2.5-polluted city in Jiangsu Province, China (during 2015–2017, daily average concentration of PM_2.5 was 52.7 μg/m³). Each participant’s demographic and health information, individual perception and pulmonary function outcomes were collected to explore the relationships between perception factors and personal characteristics and pulmonary function parameters, using linear models.

Results

We found that the mean values for controllability (5 ± 2.8) and dread of risk to oneself (levels of fear for haze-related harm to oneself) (6.9 ± 2.5) were the lowest and the highest values, respectively, in our study. Education and average family income were positively related with all individual perception factors, while age was negatively associated. A history of respiratory disease was positively associated with all individual perception factors except controllability. Significant positive associations were observed between PEF (coefficients ranged from 0.18 to 0.22) and FEF75% (coefficients ranged from 0.18 to 0.29) with a variety of individual perception factors.

Conclusions

There were a lack of concern and knowledge, weak self-protection consciousness and a strong dread of PM_2.5 pollution among the middle-aged and elderly residents in Wuxi. Their individual perceptions were associated with age, education levels, average family income, history of respiratory disease, PEF and FEF75%. Our findings may help policymakers develop effective policies and communication strategies to mitigate the hazards of haze among older residents.

Internet use and individuals' environmental quality evaluation: Evidence from China

Identifying factors that influence the public's environmental quality perception is conducive to environmental protection and risk management. By employing data from the Chinese Social Survey (CGSS) and the ordinary least squares (OLS) method, the present study aims to explore the associations between Internet use and Chinese residents' environmental quality evaluation. The results show that, compared with non-netizens, netizens have a higher negative evaluation of environmental quality, which supports the negativity bias theory, namely, that netizens pay more attention to negative news related to environmental pollution on the Internet. Further study suggests that the impact of Internet use on environmental quality evaluation is heterogeneous across different categories of environmental issues and populations: Internet use has greater effects on risk perception of environmental issues that are closely related to residents' lives. In addition, Internet use has a greater negative impact on environmental quality evaluation for older people and rural residents. Finally, this paper utilizes a substitution variable method, propensity score matching (PSM) and quantile regression to conduct the robustness check.

Spatial distribution of the public's risk perception for air pollution: A nationwide study in China

Severe air pollution problems have led to a rise in the Chinese public's concern. Risk perception is one of the most important indicators of the public's concern about air pollution. However, there existed few studies exploring the spatial distribution of risk perception. To fill the gap, psychometric paradigm methods was adopted to assess the public's risk perception of air pollution. A nationwide empirical study was conducted from December 2016 to February 2017 and 10,653 completed questionnaires were collected. According to a series of screening strategies, 9744 qualified questionnaires were included as a sample, which covered 31 China provinces (Hong Kong, Macao and Taiwan were not included in this study). We found that 45% of the respondents were dissatisfied with the current air quality, many respondents concerned a lot about air pollution (76%) and worried about the harmful consequences of being exposed to air pollution (86%). There was significant difference in the public's risk perception and attitude toward air pollution among different regions: the respondents in the northeast region, northern coastal region, eastern coastal region and Middle Yellow river region perceived higher air pollution risk and lower satisfaction with air quality than other regions; and the public's trust in the government increased from coastal regions to inland regions. In addition, the hierarchical linear model (HLM) was used to explore the effects of demographic, environmental and economic factors on public risk perception and attitude toward air pollution. Based on this, the characteristics of sensitive populations regarding air pollution were identified. What's more, we found that PM_2.5 has a positive influence on perceived risk factor (PR) and can strengthen the positive correlation between PR and satisfaction with air quality (SAQ). Finally, policy implications behind these results were discussed, which can provide references and lay the foundation for policymakers and subsequent researchers.

Perceived air quality and particulate matter pollution based on field survey data during a winter period

Outdoor air pollution and especially particulate matter pollution is a major environmental health issue that raises concerns of scientists and policy makers. This study focuses on air quality perception in relation to particulate matter in order to find potential patterns. Field questionnaire-based surveys were conducted among pedestrians on two central sites in the city of Athens, Greece, during the winter period while particulate matter of 10 μm or less in diameter (PM₁₀) were concurrently measured on-site at 1-min resolution. The participants were asked to evaluate the dust and the overall pollution-related air quality based on 5-point bipolar scales. Air quality perception patterns were explored considering PM₁₀ concentration, meteorological and thermal conditions, and subjective variables including gender, age, smoking status, and health status. An effect of PM₁₀ on dust perception was identified, suggesting that dusty air quality conditions are reported more frequently when particulate concentration increases. Health status, exposure time, smoking status, and gender were found to affect air quality perception. Participants experiencing health symptoms, exposed to outdoor conditions for more than 30 min, smokers, and females were more likely to report unfavorable air quality conditions. The comparison with the results of a previous study obtained using air pollution station data confirmed the dependence of air quality perception on participants' characteristics and particularly on their health status. Ordinal logistic regression models showed that for pedestrians who were neither smokers nor experiencing health symptoms and were exposed to outdoor conditions for more than 30 min, a PM₁₀ concentration around 64 μg·m^-3 could be a threshold, to perceive dusty air quality conditions.

A review of factors surrounding the air pollution exposure to in-pram babies and mitigation strategies

Air pollution exposure to in-pram babies poses a serious threat to their early childhood development, necessitating a need for effective mitigation measures. We reviewed the scientific and grey literature on in-pram babies and their personal exposure to traffic generated air pollutants such as particulate matter ≤10 μm (PM₁₀), ≤2.5 μm (PM_2.5), ≤0.10 μm (ultrafine particles) in size, black carbon and nitrogen oxides and potential mitigation pathways. In-pram babies can be exposed up to ~60% higher average concentrations depending on the pollutant types compared with adults. The air within the first few meters above the road level is usually most polluted. Therefore, we classified various pram types based on criteria such as height, width and the seating capacity (single versus twin) and assessed the breathing heights of sitting babies in various pram types available in the market. This classification revealed the pram widths between 0.56 and 0.82 m and top handle heights up to ~1.25 m as opposed to breathing height between 0.55 and 0.85 m, suggesting that the concentration within the first meter above the road level is critical for exposure to in-pram babies. The assessment of flow features around the prams suggests that meteorological conditions (e.g., wind speed and direction) and traffic-produced turbulence affect the pollution dispersion around them. A survey of the physicochemical properties of particles from roadside environment demonstrated the dominance of toxic metals that have been shown to damage their frontal lobe as well as cognition and brain development when inhaled by in-pram babies. We then assessed a wide range of active and passive exposure mitigation strategies, including a passive control at the receptor such as the enhanced filtration around the breathing zone and protection of prams via covers. Technological solutions such as creating a clean air zone around the breathing area can provide instant solutions. However, a holistic approach involving a mix of innovative technological solutions, community empowerment and exposure-centric policies are needed to help limit personal exposure of in-pram babies.