Meta-analysis on short-term exposure to ambient ultrafine particles and respiratory morbidity

Predicting within-city spatiotemporal variations in daily median outdoor ultrafine particle number concentrations and size in Montreal and Toronto, Canada

Background

Epidemiological evidence suggests that long-term exposure to outdoor ultrafine particles (UFPs, <0.1 μm) may have important human health impacts. However, less is known about the acute health impacts of these pollutants as few models are available to estimate daily within-city spatiotemporal variations in outdoor UFPs.

Methods

Several machine learning approaches (i.e., generalized additive models, random forest models, and extreme gradient boosting) were used to predict daily spatiotemporal variations in outdoor UFPs (number concentration and size) across Montreal and Toronto, Canada using a large database of mobile monitoring measurements. Separate models were developed for each city and all models were evaluated using a 10-fold cross-validation procedure.

Results

In total, our models were based on measurements from 12,705 road segments in Montreal and 10,929 road segments in Toronto. Daily median outdoor UFP number concentrations varied substantially across both cities with 1st-99th percentiles ranging from 1389 to 181,672 in Montreal and 2472 to 118,544 in Toronto. Outdoor UFP size tended to be smaller in Montreal (mean [SD]: 34 nm [15]) than in Toronto (mean [SD]: 44 nm [25]). Extreme gradient boosting models performed best and explained the majority of spatiotemporal variations in outdoor UFP number concentrations (Montreal, R 2: 0.727; Toronto, R 2: 0.723) and UFP size (Montreal, R 2: 0.823; Toronto, R 2: 0.898) with slopes close to one and intercepts close to zero for relationships between measured and predicted values.

Conclusion

These new models will be applied in future epidemiological studies examining the acute health impacts of outdoor UFPs in Canada's two largest cities.

The Impact of the Reduction in Environmental Pollution during COVID-19 Lockdown on Healthy Individuals

The lockdown imposed to combat the COVID-19 pandemic produced a historic fall in air pollution in cities like Barcelona. This exceptional situation offered a unique context in which to examine the effects of air pollutants on human health. The present study aims to determine and compare the oxidative stress biomarkers Th1/Th2 and inflammatory-related cytokines in healthy individuals first during lockdown and then six months after the easing of the restrictions on mobility. A prospective study of a representative sample of 58 healthy, non-smoking adults was carried out. During lockdown and six months post-easing of restrictions, blood samples were drawn to measure the percentage of eosinophils, levels of Th1/Th2 and inflammatory-related cytokines assessed by a multiplex assay (BioRad Laboratories S.A., Marnes-la-Coquette, France), and levels of 8-isoprostane, glutathione peroxidase activity, and myeloperoxidase (Cayman Chemical Co., Ann Arbor, MI, USA), to assess their value as biomarkers of oxidative stress. Six months after easing mobility restrictions, increases in the levels of 8-isoprostane (p < 0.0001), IL-1β (p = 0.0013), IL-1ra (p = 0.0110), IL-4 (p < 0.0001), IL-13 (p < 0.0001), G-CSF (p = 0.0007), and CCL3 (p < 0.0001) were recorded, along with reductions in glutathione peroxidase (p < 0.0001), IFN-γ (p = 0.0145), TNFα (p < 0.0001), IP-10 (p < 0.0001), IL-2 (p < 0.0001), IL-7 (p < 0.0001), basic FGF (p < 0.0001), CCL4 (p < 0.0001), and CCL5 (p < 0.0001). No significant differences were observed in the rest of the biomarkers analyzed. The reduction in environmental pollution during the COVID-19 lockdown significantly lowered the levels of oxidative stress, systemic inflammation, and Th2-related cytokines in healthy people.

Association between air pollution and emergency room admission for eye diseases in Rome, Italy: A time-series analysis

Eye diseases impose a significant burden on health services due to high case numbers. However, exposure to outdoor air pollution is seldom mentioned as potential harmful factor. We conducted a time-series analysis in Rome, Italy, to estimate the association between daily mean concentration of NO2, PM10 and PM2.5 and daily number of emergency room (ER) admissions for a selected cluster of eye diseases from 2006 to 2016. We used Poisson regression adjusted for time trend, population decrease during summer vacations and holidays, day of week, apparent temperature (hot and cold) and daily concentration of nine pollen species. We observed 581,868 ER admissions during the study period. 44.74% of cases were observed in subjects with less than 20 years, 19.50% in 51-65 age category and 13.4% among children (0-14 years). No differences between sexes were recorded. Mean values of pollutant concentrations were 54.75, 31.01 and 18.14 μg/m3 for NO2, PM10 and PM2.5 respectively. The air temperature ranged from -1 °C to 32.5 °C, with a mean value of 16 °C (SD = 6.88). The apparent temperature spaced from -3.58 °C to 34.08 °C (mean = 15.61 °C, SD = 8.5). The highest percent risk increases for 10 μg/m3 increases of the three pollutants were observed at lag0-1 day (1.3%, 0.63-1.98 for PM2.5; 1.03%, 0.56-1.51 for PM10 and 0.6%, 0.13-1.07 for NO2). Risk increased significantly also at lag0 and lag0-5 day for each pollutant. Secondary analyses showed higher effects in the elderly compared to younger subjects. No differences emerged between sexes. The dose response analysis suggested of possible effects on ER admission risk also at low-level concentrations of PM2.5. A strong confounding effect of pollen was not detected. RESULTS: of this study are coherent with previous analyses. Speculation can be done about the biological mechanisms that link air pollution to eye damage.

Indoor exposure to ultrafine particles related to domestic activities: A systematic review and meta-analysis

Ultrafine particles (< 100 nm) are of increasing concern because of their toxicological potential. Emission processes suggest their presence in all environments, including at home, where particularly at-risk populations may be exposed. However, knowledge of their impact on health is still limited, due to difficulties in properly assessing exposure in epidemiological studies. In this context, the objective of this study was to provide a complete summary of indoor exposure to ultrafine particles in highly industrialised countries by examining the domestic activities that influence such exposure. We conducted a systematic review, according to PRISMA guidelines using PubMed, Web of Science and Scopus up to and including 2021. We carried out a qualitative and quantitative analysis of the selected studies with a standardised template. Exposure circumstances, measurement methods, and results were analysed. Finally, a meta-analysis of the measured concentrations was performed to study exposure levels during domestic activities. The review included 69 studies resulting in the analysis of 346 exposure situations. Nine main groups of activities were identified: cooking, which was the most studied, smoking, the use of air-fresheners, cleaning, heating, personal care, printing, do-it-yourself activities, and others. Over 50 different processes were involved in these activities. Based on available particle number concentrations, the highest average of mean concentrations was associated with grilling (14,400 × 103 cm-3), and the lowest with wood stove (18 × 103 cm-3). The highest average of peak concentrations was that for the use of hair dryers (695 × 103 cm-3), and the lowest for the use of air cleaners (11 × 103 cm-3). A hierarchy of domestic activities and related processes leading to ultrafine particle exposure is provided, along with average exposure concentrations at home. However, more extensive measurement campaigns are needed under real-life conditions to improve assessments of indoor exposure to ultrafine particles.

The Berlin-Brandenburg Air Study-A Methodological Study Paper of a Natural Experiment Investigating Health Effects Related to Changes in Airport-Related Exposures

Objectives: This paper presents the study design of the Berlin-Brandenburg Air study (BEAR-study). We measure air quality in Berlin and Brandenburg before and after the relocation of aircraft (AC) traffic from Tegel (TXL) airport to the new Berlin-Brandenburg airport (BER) and investigate the association of AC-related ultrafine particles (UFP) with health outcomes in schoolchildren. Methods: The BEAR-study is a natural experiment examining schoolchildren attending schools near TXL and BER airports, and in control areas (CA) away from both airports and associated air corridors. Each child undergoes repeated school-based health-examinations. Total particle number concentration (PNC) and meteorological parameters are continuously monitored. Submicrometer particle number size distribution, equivalent black carbon, and gas-phase pollutants are collected from long-term air quality monitoring stations. Daily source-specific UFP concentrations are modeled. We will analyze short-term effects of UFP on respiratory, cardiovascular, and neurocognitive outcomes, as well as medium and long-term effects on lung growth and cognitive development. Results: We examined 1,070 children (as of 30 November 2022) from 16 schools in Berlin and Brandenburg. Conclusion: The BEAR study increases the understanding of how AC-related UFP affect children's health.

Short-term exposure to ultrafine particles and mortality and hospital admissions due to respiratory and cardiovascular diseases in Copenhagen, Denmark

Ultrafine particles (UFP; particulate matter <0.1 μm in diameter) may be more harmful to human health than larger particles, but epidemiological evidence on their health effects is still limited. In this study, we examined the association between short-term exposure to UFP and mortality and hospital admissions in Copenhagen, Denmark. Daily concentrations of UFP (measured as particle number concentration in a size range 11-700 nm) and meteorological variables were monitored at an urban background station in central Copenhagen during 2002-2018. Daily counts of deaths from all non-accidental causes, as well as deaths and hospital admissions from cardiovascular and respiratory diseases were obtained from Danish registers. Mortality and hospital admissions associated with an interquartile range (IQR) increase in UFP exposure on a concurrent day and up to six preceding days prior to the death or admission were examined in a case-crossover study design. Odds ratios (OR) with 95% confidence intervals (CI) per one IQR increase in UFP were estimated after adjusting for temperature and relative humidity. We observed 140,079 deaths in total, 236,003 respiratory and 342,074 cardiovascular hospital admissions between 2002 and 2018. Hospital admissions due to respiratory and cardiovascular diseases were significantly positively associated with one IQR increase in UFP (OR: 1.04 [95% CI: 1.01, 1.07], lag 0-4, and 1.02 [1.00, 1.04], lag 0-1, respectively). Among the specific causes, the strongest associations were found for chronic obstructive pulmonary disease (COPD) mortality and asthma hospital admissions and two-day means (lag 0-1) of UFP (OR: 1.13 [1.01, 1.26] and 1.08 [1.00, 1.16], respectively, per one IQR increase in UFP). Based on 17 years of UFP monitoring data, we present novel findings showing that short-term exposure to UFP can trigger respiratory and cardiovascular diseases mortality and morbidity in Copenhagen, Denmark. The strongest associations with UFP were observed with COPD mortality and asthma hospital admissions.

The impact of COVID-19 lockdown restrictions on the short-term association between in-vehicle particulate pollutants and the respiratory health of Parisian taxi drivers

OBJECTIVES

This study assessed the short-term associations between in-vehicle ultrafine particles (UFP) and black carbon (BC) concentrations and irritation symptoms and lung parameters of taxi drivers, pre- and post-lockdown.

METHODS

As part of PUF-TAXI project, 33 taxi drivers were followed up during two typical working days. In-vehicle UFP and BC were continuously measured by monitoring instruments. Irritation symptoms during the working day were reported via an auto-questionnaire and lung function was assessed by a portable spirometer, pre- and post- work shift. Generalized estimating equations, adjusted for potential confounders, were used to study the association between air pollutants and health outcomes. Effect modification by measurement period (pre- and post-lockdown) was investigated.

RESULTS

UFP and BC concentrations inside taxi vehicles decreased significantly post- compared to pre-lockdown. Incidence of nose irritation was positively associated with in-vehicle UFP and BC levels pre-lockdown, when pollutant levels were higher, whereas no significant association was found post-lockdown. The decrease in the FEF25-75% (forced expiratory flow at 25-75% of the forced vital capacity) during the working day was significantly associated with in-taxi UFP levels before but not after lockdown. No association was found with BC. By contrast, incidence of eye irritation was significantly inversely associated with in-vehicle humidity, regardless of pollutant concentrations and the measurement period.

CONCLUSIONS

Our findings indicate that an upgrade in in-vehicle air quality could improve respiratory health. This study showed that the magnitude of the incidence of nasal irritation and decrease in lung function depends on UFP concentrations the commuters are exposed to.

Toxicity and health effects of ultrafine particles: Towards an understanding of the relative impacts of different transport modes

Exposure to particulate matter (PM) has been associated with a wide range of adverse health effects, but it is still unclear how particles from various transport modes differ in terms of toxicity and associations with different human health outcomes. This literature review aims to summarize toxicological and epidemiological studies of the effect of ultrafine particles (UFPs), also called nanoparticles (NPs, <100 nm), from different transport modes with a focus on vehicle exhaust (particularly comparing diesel and biodiesel) and non-exhaust as well as particles from shipping (harbor), aviation (airport) and rail (mainly subway/underground). The review includes both particles collected in laboratory tests and the field (intense traffic environments or collected close to harbor, airport, and in subway). In addition, epidemiological studies on UFPs are reviewed with special attention to studies aimed at distinguishing the effects of different transport modes. Results from toxicological studies indicate that both fossil and biodiesel NPs show toxic effects. Several in vivo studies show that inhalation of NPs collected in traffic environments not only impacts the lung, but also triggers cardiovascular effects as well as negative impacts on the brain, although few studies compared NPs from different sources. Few studies were found on aviation (airport) NPs, but the available results suggest similar toxic effects as traffic-related particles. There is still little data related to the toxic effects linked to several sources (shipping, road and tire wear, subway NPs), but in vitro results highlighted the role of metals in the toxicity of subway and brake wear particles. Finally, the epidemiological studies emphasized the current limited knowledge of the health impacts of source-specific UFPs related to different transport modes. This review discusses the necessity of future research for a better understanding of the relative potencies of NPs from different transport modes and their use in health risk assessment.

Impact of ultrafine particles and total particle number concentration on five cause-specific hospital admission endpoints in three German cities

INTRODUCTION

Numerous studies have shown associations between daily concentrations of fine particles (e.g., particulate matter with an aerodynamic diameter ≤2.5 µm; PM2.5) and morbidity. However, evidence for ultrafine particles (UFP; particles with an aerodynamic diameter of 10-100 nm) remains conflicting. Therefore, we aimed to examine the short-term associations of UFP with five cause-specific hospital admission endpoints for Leipzig, Dresden, and Augsburg, Germany.

MATERIAL AND METHODS

We obtained daily counts of (cause-specific) cardiorespiratory hospital admissions between 2010 and 2017. Daily average concentrations of UFP, total particle number (PNC; 10-800 nm), and black carbon (BC) were measured at six sites; PM2.5 and nitrogen dioxide (NO2) were obtained from monitoring networks. We assessed immediate (lag 0-1), delayed (lag 2-4, lag 5-7), and cumulative (lag 0-7) effects by applying station-specific confounder-adjusted Poisson regression models. We then used a novel multi-level meta-analytical method to obtain pooled risk estimates. Finally, we performed two-pollutant models to investigate interdependencies between pollutants and examined possible effect modification by age, sex, and season.

RESULTS

UFP showed a delayed (lag 2-4) increase in respiratory hospital admissions of 0.69% [95% confidence interval (CI): -0.28%; 1.67%]. For other hospital admission endpoints, we found only suggestive results. Larger particle size fractions, such as accumulation mode particles (particles with an aerodynamic diameter of 100-800 nm), generally showed stronger effects (respiratory hospital admissions & lag 2-4: 1.55% [95% CI: 0.86%; 2.25%]). PM2.5 showed the most consistent associations for (cardio-)respiratory hospital admissions, whereas NO2 did not show any associations. Two-pollutant models showed independent effects of PM2.5 and BC. Moreover, higher risks have been observed for children.

CONCLUSIONS

We observed clear associations with PM2.5 but UFP or PNC did not show a clear association across different exposure windows and cause-specific hospital admissions. Further multi-center studies are needed using harmonized UFP measurements to draw definite conclusions on the health effects of UFP.

Assessment of coarse, fine, and ultrafine particulate matter at different microenvironments of fire stations

The concentrations of respirable particulate matter (PM) and the impact on indoor air quality in occupational settings remains poorly characterized. This study assesses, for the first time, the cumulative and non-cumulative concentrations of 14 fractions of coarse (3.65-9.88 μm), fine (0.156-2.47 μm), and ultrafine (0.015-0.095 μm) PM inside the garage of heavy vehicles, firefighting personal protective equipment' storage room, bar, and a common area of seven Portuguese fire stations. Sampling campaigns were performed during a regular work week at the fire stations. Levels of daily total cumulative PM ranged from 277.4 to 413.2 μg/m³ (maximum values of 811.4 μg/m³), with the bar (370.1 μg/m³) and the PPE' storage room (361.3 μg/m³) presenting slightly increased levels (p > 0.05) than the common area (324.8 μg/m³) and the garage (339.4 μg/m³). The location of the sampling site, the proximity to local industries and commercial activities, the layout of the building, the heating system used, and indoor sources influenced the PM concentrations. Fine (193.8-301.0 μg/m³) and ultrafine (41.3-78.2 μg/m³) particles were predominant in the microenvironments of all fire stations and accounted for 71.5% and 17.8% of daily total cumulative levels, respectively; coarse particles (23.3-47.1 μg/m³) represented 10.7% of total PM. The permissible exposure limit (5.0 mg/m³) defined by the Occupational Safety and Health Organization for respirable dust was not overcome in the evaluated fire stations. Results suggest firefighters' regular exposure to fine and ultrafine PM inside fire stations which will contribute to cardiorespiratory health burden. Further studies are needed to characterize firefighters' exposure to fine and ultrafine PM inside fire stations, identify main emission sources, and evaluate the contribution of exposures at fire stations to firefighters' occupational health risks.

Impact of Ambient Ultrafine Particles on Cause-Specific Mortality in Three German Cities

Rationale: Exposure to ambient air pollution has been associated with adverse effects on morbidity and mortality. However, the evidence for ultrafine particles (UFPs; 10-100 nm) based on epidemiological studies remains scarce and inconsistent. Objectives: We examined associations between short-term exposures to UFPs and total particle number concentrations (PNCs; 10-800 nm) and cause-specific mortality in three German cities: Dresden, Leipzig, and Augsburg. Methods: We obtained daily counts of natural, cardiovascular, and respiratory mortality between 2010 and 2017. UFPs and PNCs were measured at six sites, and measurements of fine particulate matter (PM2.5; ⩽2.5 μm in aerodynamic diameter) and nitrogen dioxide were collected from routine monitoring. We applied station-specific confounder-adjusted Poisson regression models. We investigated air pollutant effects at aggregated lags (0-1, 2-4, 5-7, and 0-7 d after UFP exposure) and used a novel multilevel meta-analytical method to pool the results. Additionally, we assessed interdependencies between pollutants using two-pollutant models. Measurements and Main Results: For respiratory mortality, we found a delayed increase in relative risk of 4.46% (95% confidence interval, 1.52 to 7.48%) per 3,223-particles/cm3 increment 5-7 days after UFP exposure. Effects for PNCs showed smaller but comparable estimates consistent with the observation that the smallest UFP fractions showed the largest effects. No clear associations were found for cardiovascular or natural mortality. UFP effects were independent of PM2.5 in two-pollutant models. Conclusions: We found delayed effects for respiratory mortality within 1 week after exposure to UFPs and PNCs but no associations for natural or cardiovascular mortality. This finding adds to the evidence on the independent health effects of UFPs.

Emergency Department Visits in Children Associated with Exposure to Ambient PM1 within Several Hours

BACKGROUND

Emerging evidence has integrated short-term exposure to PM₁ with children's morbidity and mortality. Nevertheless, most available studies have been conducted on a daily scale, ignoring the exposure variations over the span of a day.

OBJECTIVE

The main intention of this study was to examine the association between pediatric emergency department visits (PEDVs) and intra-day exposures to PM₁ and PM_2.5. We also aimed to investigate whether a high PM₁/PM_2.5 ratio elevated the risk of PEDVs independent from PM_2.5 exposure within several hours.

METHODS

We collected hourly data on aerial PM₁ and PM_2.5 concentrations, all-cause PEDVs, and meteorological factors from two megacities (i.e., Guangzhou and Shenzhen) in southern China during 2015-2016. Time-stratified case-crossover design and conditional logistic regression analysis were used to assess the associations of PEDVs with exposures to PM₁ and PM_2.5 at different lag hours. The contribution of PM₁ to PM_2.5-associated risk was quantified by introducing PM₁/PM_2.5 ratio as an additional exposure indicator in the analysis adjusting for PM_2.5. Subgroup analyses were performed stratified by sex, age, and season.

RESULTS

During this study period, 97,508 and 101,639 children were included from Guangzhou and Shenzhen, respectively. PM₁ and PM_2.5 exposures within several hours were both remarkably related to an increased risk of PEDVs. Risks for PEDVs increased by 3.9% (95% confidence interval [CI]: 2.7-5.0%) in Guangzhou and 3.2% (95% CI: 1.9-4.4%) in Shenzhen for each interquartile range (Guangzhou: 21.4 μg/m³, Shenzhen: 15.9 μg/m³) increase in PM₁ at lag 0-3 h, respectively. A high PM₁/PM_2.5 ratio was substantially correlated with increased PEDVs, with an excess risk of 2.6% (95% CI: 1.2-4.0%) at lag 73-96 h in Guangzhou and 1.2% (95% CI: 0.4-2.0%) at lag 0-3 h in Shenzhen. Stratified analysis showed a clear seasonal pattern in PM-PEDVs relationships, with notably stronger risks in cold months (October to March of the following year) than in warm months (April to September).

CONCLUSIONS

Exposures to ambient PM₁ and PM_2.5 within several hours were related to increased PEDVs. A high PM₁/PM_2.5 ratio may contribute an additional risk independent from the short-term impacts of PM_2.5. These findings highlighted the significance of reducing PM₁ in minimizing health risks due to PM_2.5 exposure in children.

[The role of the pulmonologist in an armed conflict]

INTRODUCTION

Recent news points to the eventuality of an armed conflict on the national territory.

STATE OF THE ART

In this situation, pulmonologists will in all likelihood have a major role to assume in caring for the injured, especially insofar as chest damage is a major cause of patient death.

PERSPECTIVES

The main injuries that pulmonologists may be called upon to treat stem not only from explosions, but also from chemical, biological and nuclear hazards. In this article, relevant organizational and pedagogical aspects are addressed. Since exhaustiveness on this subject is unattainable, we are proposing training on specific subjects for interested practitioners.

CONCLUSION

The resilience of the French health system in a situation of armed conflict depends on the active participation of all concerned parties. With this in mind, it is of prime importance that the pneumological community be sensitized to the potential predictable severity of war-related injuries.

Exposure to construction dust and health impacts - A review

Construction dust contributes a significant proportion of airborne particulate matter, affecting the health of its surrounding environment and population. Construction workers are normally exposed to dust at high levels and bear severe health risks. The existing articles concerning the exposure and health impacts of construction dust are limited, but this research field has received more and more attention. This work reviews literature in the field and tries to systematically assess the current research state. Here, we review (1) methods used to monitor or sample construction dust; (2) main characteristics of construction dust, including dust classification, exposed populations, and exposure concentrations; (3) potential health hazards and (4) health risk assessment of construction dust. From existing literature, the exposure concentrations of different types and sources of construction dust are usually the focus of attention, while its particle size distribution and chemical composition are rarely mentioned. The classification and characteristics of populations exposed to construction dust ought to be a key consideration but not clear enough so far. There still lacks in-depth study of health hazards and systematic assessment of risks associated with construction dust. In future, it is valuable to develop utility instruments to precisely monitor construction dust. Besides, control means to reduce the pollution of construction dust deserve more studies. Health hazards of construction dust should be verified by biological experiments. Moreover, emerging algorithm models should be utilized in the risk assessment. The findings will help gain a better understanding of construction dust exposure and associated health risks.

Ambient ultrafine particles and asthma onset until age 20: The PIAMA birth cohort

RATIONALE

Evidence regarding the role of long-term exposure to ultrafine particles (<0.1 μm, UFP) in asthma onset is scarce.

OBJECTIVES

We examined the association between exposure to UFP and asthma development in the Dutch PIAMA (Prevention and Incidence of Asthma and Mite Allergy) birth cohort and assessed whether there is an association with UFP, independent of other air pollutants.

METHODS

Data from birth up to age 20 years from 3687 participants were included. Annual average exposure to UFP at the residential addresses was estimated with a land-use regression model. Overall and age-specific associations of exposure at the birth address and current address at the time of follow-up with asthma incidence were assessed using discrete-time hazard models adjusting for potential confounders. We investigated both single- and two-pollutant models accounting for co-exposure to other air pollutants (PM_2.5 and PM₁₀ mass concentrations, nitrogen dioxide, and PM_2.5 absorbance).

MEASUREMENTS AND MAIN RESULTS

A total of 812 incident asthma cases were identified. Overall, we found that higher UFP exposure was associated with higher asthma incidence (adjusted odds ratio (95% confidence interval) 1.08 (1.02,1.14) and 1.06 (1.00, 1.12) per interquartile range increase in exposure at the birth address and current address at the time of follow-up, respectively). Age-specific associations were not consistent. The association was no longer significant after adjustment for other traffic-related pollutants (nitrogen dioxide and PM_2.5 absorbance).

CONCLUSIONS

Our findings support the importance of traffic-related air pollutants for asthma development through childhood and adolescence, but provide little support for an independent effect of UFP.

Outdoor particulate matter exposure and upper respiratory tract infections in children and adolescents: A systematic review and meta-analysis

BACKGROUND

While the relationship between outdoor particulate matter (PM) and lower respiratory tract infections in children and adolescents is accepted, we know little about the impacts of outdoor PM on the risk of developing or aggravating upper respiratory tract infections (URTIs).

METHODS

We aimed to review the literature examining the relationship between outdoor PM exposure and URTIs in children and adolescents. A systematic search of EMBASE, MEDLINE, PubMed, Scopus, CINAHL and Web of Science databases was undertaken on April 3, 2020 and October 27, 2021. Comparable short-term studies of time-series or case-crossover designs were pooled in meta-analyses using random-effects models, while the remainder of studies were combined in a narrative analysis. Quality, risk of bias and level of evidence for health effects were appraised using a combination of emerging frameworks in environmental health.

RESULTS

Out of 1366 articles identified, 34 were included in the systematic review and 16 of these were included in meta-analyses. Both PM_2.5 and PM₁₀ levels were associated with hospital presentations for URTIs (PM_2.5: RR = 1.010, 95%CI = 1.007-1.014; PM₁₀: RR = 1.016, 95%CI = 1.011-1.021) in the meta-analyses. Narrative analysis found unequivocally that total suspended particulates were associated with URTIs, but mixed results were found for PM_2.5 and PM₁₀ in both younger and older children.

CONCLUSION

This study found some evidence of associations between PM and URTIs in children and adolescents, the relationship strength increased with PM₁₀. However, the number of studies was limited and heterogeneity was considerable, thus there is a need for further studies, especially studies assessing long-term exposure and comparing sources.

Indoor air pollution effects on pediatric asthma are submicron aerosol particle-dependent

The school environment is crucial for the child's health and well-being. On the other hand, the data about the role of school's aerosol pollution on the etiology of chronic non-communicable diseases remain scarce. This study aims to evaluate the level of indoor aerosol pollution in primary schools and its relation to the incidence of doctor's diagnosed asthma among younger school-age children. The cross-sectional study was carried out in 11 primary schools of Vilnius during 1 year of education from autumn 2017 to spring 2018. Particle number (PNC) and mass (PMC) concentrations in the size range of 0.3-10 µm were measured using an Optical Particle Sizer (OPS, TSI model 3330). The annual incidence of doctor's diagnosed asthma in each school was calculated retrospectively from the data of medical records. The total number of 6-11 years old children who participated in the study was 3638. The incidence of asthma per school ranged from 1.8 to 6.0%. Mean indoor air pollution based on measurements in classrooms during the lessons was calculated for each school. Levels of PNC and PMC in schools ranged between 33.0 and 168.0 particles/cm³ and 1.7-6.8 µg/m³, respectively. There was a statistically significant correlation between the incidence of asthma and PNC as well as asthma and PMC in the particle size range of 0.3-1 µm (r = 0.66, p = 0.028) and (r = 0.71, p = 0.017) respectively. No significant correlation was found between asthma incidence and indoor air pollution in the particle size range of 0.3-2.5 and 0.3-10 µm.   Conclusion: We concluded that the number and mass concentrations of indoor air aerosol pollution in primary schools in the particle size range of 0.3-1 µm are primarily associated with the incidence of doctor's diagnosed asthma among younger school-age children. What is Known: • Both indoor and outdoor aerosol pollution is associated with bronchial asthma in children. What is New: • The incidence of bronchial asthma among younger school age children is related to indoor air quality in primary schools. • Aerosol pollutants in the size range of 0.3-1 µm in contrast to larger size range particles can play major role in the etiology of bronchial asthma in children.

Analysis of ways to reduce potential health risk from ultrafine and fine particles emitted from 3D printers in the makerspace

Due to the growing maker culture, maker spaces using multiple fused deposition modeling (FDM)-3D printers have spread around the world. However, the 3D printing process is known to cause the release of ultrafine and fine particles, which may have adverse health effects on occupants. Therefore, this experiment-based study was conducted on FDM-3D printers placed in an actual makerspace by the following three scenarios: the number of operating FDM-3D printers, ventilation, and measurement location to compare the concentrations of ultrafine and fine particles. In addition, the deposited dose in alveolar region for ultrafine and fine particles was predicted using a respiratory deposition model to analyze the potential health risk on occupants. As a result, the scenario-based comparison revealed that if the number of operating 3D printers is reduced by less than half, the potential health risk can be decreased by 34.1%, proper ventilation can reduce potential health risk by 55.5%, and working away from the 3D printer can also reduce potential health risk by up to 27.5%. This study analyzed the potential health risk of multiple FDM-3D printers on users in an actual makerspace, and proposed various improvement measures to reduce the potential health risk of ultrafine and fine particles.

Ageing Significantly Alters the Physicochemical Properties and Associated Cytotoxicity Profiles of Ultrafine Particulate Matters towards Macrophages

There are still significant concerns about the detrimental effects and health risks of particulate matters (PMs) on the respiratory system. Notably, a largely overlooked knowledge gap is whether the environmental ageing process would change the physicochemical properties of PMs as well as the toxic influences of PMs on macrophages. Here, we applied ambient treatment of model PMs to mimic the real O3-induced ageing process and investigated ageing-determined cytotoxicity profile changes of PMs towards macrophages. The consequent distinct bioreactivity and toxicity towards macrophages are largely attributed to the changes of species of surface O-functional groups. Importantly, we unveiled the specific interactions between aged PMs and macrophages due to the variant contents of the surface carboxyl group, resulting in the divergent inflammatory activations and immune balance in the lung. Collectively, this study unearths the significance of ageing in altering particle cytotoxicity, and also provides additional understandings for consecutive investigations on the adverse effects of air pollution on the respiratory system.

Relationship between Indoor High Frequency Size Distribution of Ultrafine Particles and Their Metrics in a University Site

Exposure to ultrafine particles (UFPs size < 100 nm) in life and work environments can contribute to adverse health effects also in terms of health burden of related diseases over time. The choice of parameters which better characterize UFPs is challenging, due to their physical-chemical properties and their variable size. It is also strictly related to the availability of different instrumental techniques. In the present study we focus on real time high frequency (1 Hz) UFPs particle size distribution (PSD) and their relationship with total particle number concentration (TPNC) and mean particle diameter (Davg) as a contribution characterizing by size the human exposure to UFPs in an indoor site of the University of Rome “Sapienza” (Italy). Further considerations about UFPs contribution to nucleation mode (NM) and accumulation mode (AM) have been highlighted, also in order to investigate the contribution of polycyclic aromatic hydrocarbons (PAHs) surface-adsorbed on indoor air particles (pPAHs). High indoor TPNC values were registered during the rush hours (early morning and mid/late afternoon) according to the outdoor influences originated from anthropogenic activities. AM mainly contribute to the indoor TPNC during working days showing high correlation with pPAHs. These findings may provide useful indications in terms of occupational exposure to UFPs since there are many evidences that indoor exposures to such pollutants may be associated with adverse health effects also in working environments.