Air Quality Guidelines Research Articles

Health benefits to the pediatric population from reduction of ambient particulate matter in Krakow, Poland

There have been few assessments of the health benefits to children of policies aimed at curbing fossil fuel-related air pollution. This has resulted in a lack of awareness regarding their positive impact on the health of this vulnerable population. We estimated the pediatric health benefits of policies targeting coal burning in one of Europe’s most polluted cities, Kraków, Poland. We combined available data on child health outcomes, related concentration-response functions, childhood population counts, and concentrations of PM2.5 and PM10 based on city-wide air monitoring in Kraków. Two exposure reduction scenarios were examined. First, we used the observed decrease in air pollutant concentrations between 2010 and 2019. Second, we hypothesized a reduction to the annual World Health Organization (WHO) air quality guideline values issued in 2005. Between 2010 and 2019, the mean annual air pollution levels in Kraków decreased for both PM2.5 and PM10. Annual average PM2.5 concentrations declined by 39.1%, reaching 23.3 μg m−3; PM10 dropped by 39.2% to 34.6 μg m−3. These reductions in air pollution can be linked to numerous actions undertaken at local and national levels. We estimate that the forgone benefits in 2010 from not having achieved the PM levels observed in 2019 (on an annual basis) included: 505 (35.7%) fewer incident cases of asthma in the 1–14 age group, 81 fewer preterm births (16.8% decrease), 52 fewer cases of low birth weight (12.3% decrease), and 59 avoided asthma hospitalizations in 0–18 year olds. Compliance with the 2005 WHO PM2.5 guidelines in 2010 would have avoided 780 incident asthma cases in the 1–14 age group (54.5% decrease), 138 preterm births (28.3% decrease), and 90 cases of low birth weight (21.2% reduction) and 219 (54.2%) fewer asthma hospitalizations in 0–18 year olds. Large health benefits were also estimated for PM10 in both scenarios. This study estimated substantial health benefits for children in Kraków, which were largely attributable to clean air policies that restrict the use of coal and other solid fuels. Kraków provides a model for other cities in Europe and beyond that are affected by coal pollution and have high rates of preterm birth, low birth weight, and respiratory illness.

Gravimetric, morphological, and chemical characterization of fine and ultrafine particulate matter inside fire stations

Poor air quality inside buildings has direct implications for human health. The activity of firefighters causes cancer and promotes the development/aggravation of cardio-respiratory diseases. The indoor air quality inside fire stations remains poorly characterized. This work assesses firefighters’ daily exposure to fine (PM2.5, PM156nm) and ultrafine (PM50.4nm, PM30.8nm) particulate matter (PM) inside three microenvironments of fire stations, and, for the first time, characterizes the morphology and elemental content of collected PM. Fine PM fractions were predominant in all microenvironments. Fine and ultrafine PM concentrations were increased in the personal protective equipment (PPE) storage room than in the common area and garage [11.84–103.5 μg/m3versus 18.67–51.89 μg/m3 and 22.57–70.69 μg/m3; p > 0.05 and 4.78–46.02 μg/m3versus 3.03–40.99 μg/m3 and 5.55–23.30 μg/m3; p > 0.05]; values were below the guideline proposed for occupational exposure to respirable dust (5.0 mg/m3). The morphological analysis revealed the presence of organic matter, microorganisms, crystals, minerals, metals, and other unidentified substances in fine/ultrafine PM. Exposure to total PM-bound metals was increased in the garage comparatively to the common area and the PPE storage room (2765.0–46586.0 pg/m3versus 2414.2–4568.6 pg/m3; p > 0.5). Cu, Zn, and Cr were the predominant PM-bound metals while Sb, Cd, and Tl were the less abundant. Exposure to PM-bound possible/probable carcinogenic metals (Ni, Cd, Sb, and Pb) accounted for 7.81–10.72% and 0.342–13.07% of fine and ultrafine PM, respectively. The data generated can support regulatory agencies in proposing air quality guidelines that promote occupational safety and health.

Impact of indoor air pollution exposure from traditional stoves on lung functions in adult women of a rural Indian district

Introduction: Biomass Fuels (BMF) used for daily cooking in developing countries inside home is the highest exposures to air pollutants. Inhalation of these pollutants causes harmful health effects. This study aims to assess the health effects with the indoor air pollutants generated BMF.
 Materials and methods: A cross-sectional study, conducted in a rural village of India. 450 households were divided into two groups based on the cooking fuel, the BMF group and the Liquefied Petroleum Gas (LPG) clean fuel group. Socioeconomic and respiratory symptoms information was obtained using a standard questionnaire. Indoor air concentration for PM10 and PM2.5 was measured during cooking hours. Pulmonary Function Tests (PFTs) were conducted for the women inhabitants using spirometer.
 Results: Respiratory symptoms like chest pain, breathlessness, eye irritation, and blackout found to be significantly higher in biomass users (P<0.05). Moreover, an increasing trend in the prevalence of symptoms/ morbid conditions observed with an increase in exposure.
 Conclusion: Findings of the study confirms that the traditional use of biomass fuels exposes all family members daily to air pollution levels that well exceed available health guidelines for indoor air quality and highlights the critical gender and age dimensions of the Household Air Pollution (HAP) problem. Women exposed to BMF smoke suffer more from health problems and are at higher risk of respiratory illnesses than other fuel users.

Low-level ambient ozone exposure associated with neutrophil extracellular traps and pro-atherothrombotic biomarkers in healthy adults

Background and aimsUncertainty of the causality determinations for ambient ozone (O3) on cardiovascular events is heightened by the limited understanding of the mechanisms involved in humans. We aimed to examine the pro-atherothrombotic impacts of O3 exposure and to explore the potential mediating roles of dysfunctional neutrophils, focusing on neutrophil extracellular traps (NETs). MethodsA longitudinal panel study of 152 healthy adults was conducted in the cool to cold months with relatively low levels of O3 between September 2019 and January 2020 in Beijing, China. Four repeated measurements of indicators reflecting atherothrombotic balance and NETs were performed for each participant. ResultsDaily average exposure levels of ambient O3 were 16.6 μg/m3 throughout the study period. Per interquartile range increase in average concentrations of O3 exposure at prior up to 7 days, we observed elevations of 200.1–276.3% in D-dimer, 27.2–36.8% in thrombin-antithrombin complex, 10.8–60.3% in plasminogen activator inhibitor 1, 13.9–21.8% in soluble P-selectin, 16.5–45.1% in matrix metalloproteinase-8, and 2.4–12.4% in lipoprotein-associated phospholipase A2. These pro-atherothrombotic changes were accompanied by endothelial activation, lung injury, and immune inflammation. O3 exposure was also positively associated with circulating NETs indicators, including citrullinated histone H3, neutrophil elastase, myeloperoxidase, and double-stranded DNA. Mediation analyses indicated that NETs could mediate O3-associated pro-atherothrombotic responses. The observational associations remained significant and robust after controlling for other pollutants, and were generally greater in participants with low levels of physical activity. ConclusionsAmbient O3 exposure was associated with significant increases in NETs and pro-atherothrombotic potential, even at exposure levels well below current air quality guidelines of the World Health Organization.

The updated WHO air quality guidelines are a big step forward but not a complete solution

The updated WHO air quality guidelines are a big step forward but not a complete solution

Corporate Green Washing and its Deleterious Impact on Environmental Society and Ethical Business Decision – in India

Current research finds that, inthe context of the Sustainable Development Goals (SDGs), consumers, governments, and other commercial organizations are embracing CSR to enhance their corporate image with environmental components that are not trulyimplemented through greenwashing. India is confronted with environmental challenges such escalating air pollution, declining food security and pollution from e-waste disposal. The WHO's 24-Hour Air Quality Guidelines' suggested limit for PM2.5 concentration I snow being exceeded by 2.8 times in India. This report discusses the findings of an empirical investigation on the relationship between environmental sustain ability and the degree of business relationships, the impact of green washing on climate change and the connection between CSR and ethical decision-making. Based on the data gathered from 200 respondents to a used questionnaire a quantitative, causal, cross-sectional study was carried out, using SPSS24.0. This paper enriches the study with further scope of analyses overemployee’sperceptionoverthe SDG.

High-resolution dispersion modelling of PM2.5, PM10, NOx and NO2 exposure in metropolitan areas in Sweden 2000‒2018 – large health gains due to decreased population exposure

Ambient air pollution remains the major environmental cause of disease. Accurate assessment of population exposure and small-scale spatial exposure variations over long time periods is essential for epidemiological studies. We estimated annual exposure to fine and coarse particulate matter (PM2.5, PM10), and nitrogen oxides (NOx, NO2) with high spatial resolution to examine time trends 2000‒2018, compliance with the WHO Air Quality Guidelines, and assess the health impact. The modelling area covered six metropolitan areas in Sweden with a combined population of 5.5 million. Long-range transported air pollutants were modelled using a chemical transport model with bias correction, and locally emitted air pollutants using source-specific Gaussian-type dispersion models at resolutions up to 50 × 50 m. The modelled concentrations were validated using quality-controlled monitoring data. Lastly, we estimated the reduction in mortality associated with the decrease in population exposure. The validity of modelled air pollutant concentrations was good (R2 for PM2.5 0.84, PM10 0.61, and NOx 0.87). Air pollution exposure decreased substantially, from a population weighted mean exposure to PM2.5 of 12.2 µg m−3 in 2000 to 5.4 µg m−3 in 2018. We estimated that the decreased exposure was associated with a reduction of 2719 (95% CI 2046–3055) premature deaths annually. However, in 2018, 65%, 8%, and 42% of residents in the modelled areas were still exposed to PM2.5, PM10, or NO2 levels, respectively, that exceeded the current WHO Air Quality Guidelines for annual average exposure. This emphasises the potential public health benefits of reductions in air pollution emissions.

Short term exposure to low level ambient fine particulate matter and natural cause, cardiovascular, and respiratory morbidity among US adults with health insurance: case time series study

ObjectiveTo estimate the excess relative and absolute risks of hospital admissions and emergency department visits for natural causes, cardiovascular disease, and respiratory disease associated with daily exposure to fine particulate...

Exposure-response associations between chronic exposure to fine particulate matter and risks of hospital admission for major cardiovascular diseases: population based cohort study

ObjectiveTo estimate exposure-response associations between chronic exposure to fine particulate matter (PM2.5) and risks of the first hospital admission for major cardiovascular disease (CVD) subtypes.DesignPopulation based cohort study.SettingContiguous US.Participants59 761...

Modeling SO2 dispersion from future eruptions in the Auckland Volcanic Field, New Zealand

Auckland city (pop. 1.7 M) is Aotearoa New Zealand’s largest city and an important economic hub. The city is built upon the active intraplate basaltic Auckland Volcanic Field (AVF). An AVF eruption would cause considerable impacts. An important component of volcanic risk management is assessing the likely volcanic hazards to help inform emergency planning and other preparedness activities. Previous volcanic hazard assessments for the AVF, particularly those for emergency planning scenarios, have modeled multiple volcanic hazards including lava flows, pyroclastic density currents, ballistic projectiles and tephra fall. Despite volcanic gas being an important and impactful hazard from intraplate basaltic field eruptions, there has been limited consideration of volcanic gas in AVF hazard assessment to date. This project is one of the first to quantitatively assess potential volcanic gas hazards for an explosive eruption scenario. For basaltic volcanism, sulfur dioxide (SO2) gas is typically the most consequential volcanic gas emitted. The aim of this exploratory study was to model SO2 dispersion from a high impact eruption during weather conditions conducive to high ground level pollutant concentrations. Since ground level SO2 concentrations are influenced by complex wind patterns resulting from interactions of locally driven flow circulations and topographically influenced weather, we modeled SO2 dispersion using the HYSPLIT model, a state-of-the art hybrid Eulerian and Lagrangian dispersion model widely used for volcanic gases, using high-resolution meteorological forcing fields given by the Weather Research and Forecasting (WRF) model.Modeled air parcel trajectories and ground level SO2 concentrations illustrate the effect of the converging sea breeze winds on SO2 dispersion. Under worst-case dispersion conditions, extensive areas of up to hundreds of square kilometers to the north and northwest of the eruption location would exceed New Zealand short-term (24 h) air quality standards and guidelines for SO2, indicating heightened health risks to downwind communities. Using this numerical modeling approach, this work presents a methodology for future applications to other AVF eruption scenarios, with a wider range of meteorological conditions that can help in exploring consequences for health services such as anticipated emergency department respiratory admissions.

Enhancing risk communication and environmental crisis management through satellite imagery and AI for air quality index estimation

Due to climate change, the air pollution problem has become more and more prominent [23]. Air pollution has impacts on people globally, and is considered one of the leading risk factors for premature death worldwide; it was ranked as number 4 according to the website [24]. A study, ‘The Global Burden of Disease,’ reported 4,506,193 deaths were caused by outdoor air pollution in 2019 [22,25]. The air pollution problem is become even more apparent when it comes to developing countries [22], including Thailand, which is considered one of the developing countries [26]. In this research, we focus and analyze the air pollution in Thailand, which has the annual average PM2.5 (particulate matter 2.5) concentration falls in between 15 and 25, classified as the interim target 2 by 2021′s WHO AQG (World Health Organization's Air Quality Guidelines) [27]. (The interim targets refer to areas where the air pollutants concentration is high, with 1 being the highest concentration and decreasing down to 4 [27,28]). However, the methodology proposed here can also be adopted in other areas as well.During the winter in Thailand, Bangkok and its surrounding metroplex have been facing the issue of air pollution (e.g., PM2.5) every year. Currently, air quality measurement is done by simply implementing physical air quality measurement devices at designated—but limited number of locations. In this work, we propose a method that allows us to estimate the Air Quality Index (AQI) on a larger scale by utilizing Landsat 8 images with machine learning techniques. We propose and compare hybrid models with pure regression models to enhance AQI predictionbased on satellite images. Our hybrid model consists of two parts as follows:•The classification part and the estimation part, whereas the pure regressor model consists of only one part, which is a pure regression model for AQI estimation.•The two parts of the hybrid model work hand in hand such that the classification part classifies data points into each class of air quality standard, which is then passed to the estimation part to estimate the final AQI.From our experiments, after considering all factors and comparing their performances, we conclude that the hybrid model has a slightly better performance than the pure regressor model, although both models can achieve a generally minimum R2 (R2 > 0.7). We also introduced and tested an additional factor, DOY (day of year), and incorporated it into our model. Additional experiments with similar approaches are also performed and compared. And, the results also show that our hybrid model outperform them.Keywords: climate change, air pollution, air quality assessment, air quality index, AQI, machine learning, AI, Landsat 8, satellite imagery analysis, environmental data analysis, natural disaster monitoring and management, crisis and disaster management and communication.

Source differences in the components and cytotoxicity of PM2.5 from automobile exhaust, coal combustion, and biomass burning contributing to urban aerosol toxicity

Abstract. Although air quality guidelines generally use the atmospheric concentration of fine particulate matter (PM2.5) as a metric for air pollution evaluation and management, the fact cannot be ignored that different particle toxicities are unequal and significantly related to their sources and chemical compositions. Therefore, judging the most harmful source and identifying the toxic component would be helpful for optimizing air quality standards and prioritizing targeted PM2.5 control strategies to protect public health more effectively. Since the combustions of fuels, including oil, coal, and biomass, are the main anthropogenic sources of environmental PM2.5, their discrepant contributions to health risks of mixed ambient aerosol pollution dominated by the respective emission intensity and unequal toxicity of chemical components need to be identified. In order to quantify the differences between these combustion primary emissions, 10 types of PM2.5 from each typical source group, i.e., vehicle exhaust, coal combustion, and plant biomass (domestic biofuel) burning, were collected for comparative study with toxicological mechanisms. In total, 30 types of individual combustion samples were intercompared with representative urban ambient air PM2.5 samples, whose chemical characteristics and biological effects were investigated by component analysis (carbon, metals, soluble ions) and in vitro toxicity assays (cell viability, oxidative stress, inflammatory response) of human lung adenocarcinoma epithelial cells (A549). Carbonaceous fractions were plenteous in automobile exhaust and biomass burning, while heavy metals were more plentiful in PM2.5 from coal combustion and automobile exhaust. The overall ranking of mass-normalized cytotoxicity for source-specific PM2.5 was automobile exhaust > coal combustion > domestic plant biomass burning > ambient urban air, possibly with differential toxicity triggers, and showed that the carbonaceous fractions (organic carbon, OC; elemental carbon, EC) and redox-active transition metals (V, Ni, Cr) assisted by water-soluble ions (Ca2+, Mg2+, F−, Cl−) might play important roles in inducing cellular reactive organic species (ROS) production, causing oxidative stress and inflammation, resulting in cell injury and apoptosis, and thus damaging human health. Coupled with the source apportionment results of typical urban ambient air PM2.5 in eastern China, reducing toxic PM2.5 from these anthropogenic combustions will be greatly beneficial to public health. In addition to the air pollution control measures that have been implemented, like strengthening the vehicle emission standards, switching energy from coal to gas and electricity, and controlling the open incineration of agricultural straws, further methods could be considered, especially by preferentially reducing the diesel exhaust, lessening the coal combustion by replacement with low-ash clean coals, and depressing the rural crop straw biomass burning emissions.

Environmental and social inequities in continental France: an analysis of exposure to heat, air pollution, and lack of vegetation.

Cumulative environmental exposures and social deprivation increase health vulnerability and limit the capacity of populations to adapt to climate change. Our study aimed at providing a fine-scale characterization of exposure to heat, air pollution, and lack of vegetation in continental France between 2000 and 2018, describing spatiotemporal trends and environmental hotspots (i.e., areas that cumulate the highest levels of overexposure), and exploring any associations with social deprivation. The European (EDI) and French (FDep) social deprivation indices, the normalized difference vegetation index, daily ambient temperatures, particulate matter (PM2.5 and PM10), nitrogen dioxide, and ozone (O3) concentrations were estimated for 48,185 French census districts. Reference values were chosen to characterize (over-)exposure. Hotspots were defined as the areas cumulating the highest overexposure to temperature, air pollution, and lack of vegetation. Associations between heat overexposure or hotspots and social deprivation were assessed using logistic regressions. Overexposure to heat was higher in 2015-2018 compared with 2000-2014. Exposure to all air pollutants except for O3 decreased during the study period. In 2018, more than 79% of the urban census districts exceeded the 2021 WHO air quality guidelines. The evolution of vegetation density between 2000 and 2018 was heterogeneous across continental France. In urban areas, the most deprived census districts were at a higher risk of being hotspots (odds ratio (OR): 10.86, 95% CI: 9.87-11.98 using EDI and OR: 1.07, 95% CI: 1.04-1.11 using FDep). We studied cumulative environmental exposures and social deprivation in French census districts. The 2015-2018 period showed the highest overexposure to heat between 2000 and 2018. In 2018, the air quality did not meet the 2021 WHO guidelines in most census districts and 8.6 million people lived in environmental hotspots. Highly socially deprived urban areas had a higher risk of being in a hotspot. This study proposes for the first time, a methodology to identify hotspots of exposure to heat, air pollution, and lack of vegetation and their associations with social deprivation at a national level.

Eco-Friendly Innovation: Hydra-Enhanced Miniature Photobioreactor for Air Pollution Reduction

According to the WHO data in 2019, nearly all of the global population resides in areas that do not meet the WHO guidelines for air quality. This study is to address the issue of indoor air pollution through the use of Photobioreactor technology and Hydrilla Verticillata plants. The experimental findings demonstrate that the rate of photosynthesis and production of oxygen bubbles by the Hydrilla plants are significantly influenced by adequate light intensity and exposure to CO2. By employing this innovative Photobioreactor technology, it is anticipated that indoor air quality can be enhanced, thereby contributing to the resolution of air pollution problems. This research adopts a combination of descriptive and experimental methods, utilizing a prototype scale for conducting experiments. Secondary data, in the form of published scientific articles from both international and national journals, serve as the source of data. The collected data is then qualitatively analyzed through descriptive means. Based on the results of data analysis, it can be concluded that this research offers valuable insights into the use of Hydrilla plants in innovative technologies for the improvement of air quality and human health, particularly by implementing photosynthesis processes within Photobioreactor technology.

Ambient air pollution and consumer spending: Evidence from Spain.

Research on the economic burden of air pollution has focused primarily on its macroeconomic impact. However, as some studies have found that air pollution can lead to avoidance behavior-for example, reducing the time spent outdoors-we hypothesize that it can also influence consumer spending activity. We combine high frequency data on ozone and fine particulate pollution with daily consumer spending in brick-and-mortar retail in 129 postal codes in Spain during 2014 to estimate the association between the two. Using a linear fixed effects model, we find that a 1-standard deviation increase in ozone concentration (20.97 μg/m3) is associated with 3.9 percent decrease in consumer spending (95% CI: -0.066, -0.012; p<0.01). The association of fine particulate matter with consumer spending is, however, not statistically significant (β: 0.005; 95% CI: -0.009, 0.018; p>0.10). Further, we do not observe a sufficiently strong bounce-back in consumer spending in the day-or even the week-following higher ozone concentration. Also, we find that the relationship between ozone concentration and consumer spending is heterogeneous, with those aged below 25 and those aged 45 or above exhibiting stronger negative association. This research informs policymakers about a plausibly unaccounted cost of ambient air pollution, even at concentrations lower than the WHO air quality guideline for short-term exposure.

Roadside PM2.5 concentrations measured with low-cost sensors and student science in Arba Minch, Ethiopia

Exposure to PM2.5 poses one of the biggest health threats, with traffic and biomass burning as dominant sources in urban areas of low-income countries. In Ethiopia, the combination of these two sources suggests a high roadside exposure. Because of a lack of resources for data collection, only few studies were conducted on roadside exposure in Ethiopia. Using low-cost sensors and student science could partially remedy this lack of resources. Students collected PM2.5 data in Arba Minch at four stationary locations and inside two public transport tricycles during a period of six weeks with self-made low-cost sensors. Data was analyzed to gain insight into concentration levels, temporal variation, spatial variation, and difference between next to the road and on-road concentrations. Average concentrations ranged from 13-36 µg/m3. Concentrations were highest during morning hours (42 ± 12 for hours 6:00-10:00, versus 20 ± 1 and 32 ± 4 for 10:00-17:00 and 17:00-21:00, respectively), and concentrations were highest at the local bus station (36.2 µg/m3). On-road concentrations showed the highest variation and were on average higher than concentrations next to the road (33 ± 25 and 30 ± 22 µg/m3 versus 23.3 ± 18 and 22.6 ± 18 µg/m3). On a daily average level, concentrations at different locations showed a high correlation (R2 0.8-0.95) amongst each other. This suggests the possibility to interpolate concentrations from one location to other locations. Moreover, the PM2.5 concentrations exceeded air quality guidelines. In Ethiopia, more than ten cities have higher populations and traffic flows than Arba Minch. In those cities, similar or higher exceedances are expected. With this study as an example, other universities could likewise conduct research with low-cost sensors and student science in their cities. Cooperation across course instructors and universities in applying these methods will increase the insight in PM2.5 exposure in Ethiopian cities.&#x0D; Keywords: ambient air pollution; traffic; Sensirion SPS30; student measurements; Particulate Matter

Exposure limits for indoor volatile substances concerning the general population: The role of population-based differences in sensory irritation of the eyes and airways for assessment factors.

Assessment factors (AFs) are essential in the derivation of occupational exposure limits (OELs) and indoor air quality guidelines. The factors shall accommodate differences in sensitivity between subgroups, i.e., workers, healthy and sick people, and occupational exposure versus life-long exposure for the general population. Derivation of AFs itself is based on empirical knowledge from human and animal exposure studies with immanent uncertainty in the empirical evidence due to knowledge gaps and experimental reliability. Sensory irritation in the eyes and airways constitute about 30-40% of OELs and is an abundant symptom in non-industrial buildings characterizing the indoor air quality and general health. Intraspecies differences between subgroups of the general population should be quantified for the proposal of more 'empirical' based AFs. In this review, we focus on sensitivity differences in sensory irritation about gender, age, health status, and vulnerability in people, based solely on human exposure studies. Females are more sensitive to sensory irritation than males for few volatile substances. Older people appear less sensitive than younger ones. However, impaired defense mechanisms may increase vulnerability in the long term. Empirical evidence of sensory irritation in children is rare and limited to children down to the age of six years. Studies of the nervous system in children compared to adults suggest a higher sensitivity in children; however, some defense mechanisms are more efficient in children than in adults. Usually, exposure studies are performed with healthy subjects. Exposure studies with sick people are not representative due to the deselection of subjects with moderate or severe eye or airway diseases, which likely underestimates the sensitivity of the group of people with diseases. Psychological characterization like personality factors shows that concentrations of volatile substances far below their sensory irritation thresholds may influence the sensitivity, in part biased by odor perception. Thus, the protection of people with extreme personality traits is not feasible by an AF and other mitigation strategies are required. The available empirical evidence comprising age, lifestyle, and health supports an AF of not greater than up to 2 for sensory irritation. Further, general AFs are discouraged for derivation, rather substance-specific derivation of AFs is recommended based on the risk assessment of empirical data, deposition in the airways depending on the substance's water solubility and compensating for knowledge and experimental gaps. Modeling of sensory irritation would be a better 'empirical' starting point for derivation of AFs for children, older, and sick people, as human exposure studies are not possible (due to ethical reasons) or not generalizable (due to self-selection). Dedicated AFs may be derived for environments where dry air, high room temperature, and visually demanding tasks aggravate the eyes or airways than for places in which the workload is balanced, while indoor playgrounds might need other AFs due to physical workload and affected groups of the general population.

Intrauterine and early postnatal exposures to submicron particulate matter and childhood allergic rhinitis: A multicity cross-sectional study in China

BackgroundAirborne particulate matter pollution has been linked to occurrence of childhood allergic rhinitis (AR). However, the relationships between exposure to particulate matter with an aerodynamic diameter ≤1 μm (PM1) during early life (in utero and first year of life) and the onset of childhood AR remain largely unknown. This study aims to investigate potential associations of in utero and first-year exposures to size-segregated PMs, including PM1, PM1–2.5, PM2.5, PM2.5–10, and PM10, with childhood AR. MethodsWe investigated 29286 preschool children aged 3–6 years in 7 Chinese major cities during 2019–2020 as the Phase II of the China Children, Families, Health Study. Machine learning-based space-time models were utilized to estimate early-life residential exposure to PM1, PM2.5, and PM10 at 1 × 1-km resolutions. The concentrations of PM1–2.5 and PM2.5–10 were calculated by subtracting PM1 from PM2.5 and PM2.5 from PM10, respectively. Multiple mixed-effects logistic models were used to assess the odds ratios (ORs) and 95% confidence intervals (CIs) of childhood AR associated with per 10-μg/m3 increase in exposure to particulate air pollution during in utero period and the first year of life. ResultsAmong the 29286 children surveyed (mean ± standard deviation, 4.9 ± 0.9 years), 3652 (12.5%) were reported to be diagnosed with AR. Average PM1 concentrations during in utero period and the first year since birth were 36.3 ± 8.6 μg/m3 and 33.1 ± 6.9 μg/m3, respectively. Exposure to PM1 and PM2.5 during pregnancy and the first year of life was associated with an increased risk of AR in children, and the OR estimates were higher for each 10-μg/m3 increase in PM1 than for PM2.5 (e.g., 1.132 [95% CI: 1.022–1.254] vs. 1.079 [95% CI: 1.014–1.149] in pregnancy; 1.151 [95% CI: 1.014–1.306] vs. 1.095 [95% CI: 1.008–1.189] in the first year of life). No associations were observed between AR and both pre- and post-natal exposure to PM1–2.5, indicating that PM1 rather than PM1–2.5 contributed to the association between PM2.5 and childhood AR. In trimester-stratified analysis, childhood AR was only found to be associated with exposure to PM1 (OR = 1.077, 95% CI: 1.027–1.128), PM2.5 (OR = 1.048, 95% CI: 1.018–1.078), and PM10 (OR = 1.032, 95% CI: 1.007–1.058) during the third trimester of pregnancy. Subgroup analysis suggested stronger PM-AR associations among younger (<5 years old) and winter-born children. ConclusionsPrenatal and postnatal exposures to ambient PM1 and PM2.5 were associated with an increased risk of childhood AR, and PM2.5-related hazards could be predominantly attributed to PM1. These findings highlighted public health significance of formulating air quality guideline for ambient PM1 in mitigating children's AR burden caused by particulate air pollution.

Ambient PM2.5 temporal variation and source apportionment in Mbarara, Uganda.

Air pollution is the leading environmental cause of death globally, and most mortality occurs in resource-limited settings such as sub-Saharan Africa. The African continent experiences some of the worst ambient air pollution in the world, yet there are relatively little African data characterizing ambient pollutant levels and source admixtures. In Uganda, ambient PM2.5 levels exceed international health standards. However, most studies focus only on urban environments and do not characterize pollutant sources. We measured daily ambient PM2.5 concentrations and sources in Mbarara, Uganda from May 2018 through February 2019 using Harvard impactors fitted with size-selective inlets. We compared our estimates to publicly available levels in Kampala, and to World Health Organization (WHO) air quality guidelines. We characterized the leading PM2.5 sources in Mbarara using x-ray fluorescence and positive matrix factorization. Daily PM2.5 concentrations were 26.7 μg m-3 and 59.4 μg m-3 in Mbarara and Kampala, respectively (p<0.001). PM2.5 concentrations exceeded WHO guidelines on 58% of days in Mbarara and 99% of days in Kampala. In Mbarara, PM2.5 was higher in the dry as compared to the rainy season (30.8 vs 21.3, p<0.001), while seasonal variation was not observed in Kampala. PM2.5 concentrations did not vary on weekdays versus weekends in either city. In Mbarara, the six main ambient PM2.5 sources identified included (in order of abundance): traffic-related, biomass and secondary aerosols, industry and metallurgy, heavy oil and fuel combustion, fine soil, and salt aerosol. Our findings confirm that air quality in southwestern Uganda is unsafe and that mitigation efforts are urgently needed. Ongoing work focused on improving air quality in the region may have the greatest impact if focused on traffic and biomass-related sources.

Long-Term Exposure to Particulate Matter and Mortality: An Update of the WHO Global Air Quality Guidelines Systematic Review and Meta-Analysis.

For the development of the 2021 global air quality guidelines, the World Health Organization (WHO) commissioned a series of systematic reviews and meta-analyses to assess the association between exposure to air pollution and all-cause and cause-specific mortality. One of these reviews, which we aim to update, focused on the effects of long-term exposure to PM2.5 and PM10 on all-cause and cause-specific mortality. The protocol for this study was registered in PROSPERO (CRD42023425327). We searched the PubMed and Embase databases for studies published between September 2018 and May 2023. Study-specific effects were pooled using random-effects models. We included 106 studies in the meta-analysis, 46 studies from the previous review and 60 from this update. All exposure-outcome pairs analysed showed positive and significant associations, except for PM10 and cerebrovascular mortality. The certainty of the evidence was rated as high for the majority of exposure-outcome pairs. We included a large number of new cohorts, and provided new concentration-response functions that will inform WHO advice on the use of this information for air pollution health risk assessments.