Road proximity influences indoor exposures to ambient fine particle mass and components

The effects of urban green space and road proximity to indoor traffic-related PM2.5, NO2, and BC exposure in inner-city schools

BACKGROUND

Since there are known adverse health impacts of traffic-related air pollution, while at the same time there are potential health benefits from greenness, it is important to examine more closely the impacts of these factors on indoor air quality in urban schools.

OBJECTIVE

This study investigates the association of road proximity and urban greenness to indoor traffic-related fine particulate matter (PM2.5), nitrogen dioxide (NO2), and black carbon (BC) in inner-city schools.

METHODS

PM2.5, NO2, and BC were measured indoors at 74 schools and outdoors at a central urban over a 10-year period. Seasonal urban greenness was estimated using the Normalized Difference Vegetation Index (NDVI) with 270 and 1230 m buffers. The associations between indoor traffic-related air pollution and road proximity and greenness were investigated with mixed-effects models.

RESULTS

The analysis showed linear decays of indoor traffic-related PM2.5, NO2, and BC by 60%, 35%, and 22%, respectively for schools located at a greater distance from major roads. The results further showed that surrounding school greenness at 270 m buffer was significantly associated (p < 0.05) with lower indoor traffic-related PM2.5: -0.068 (95% CI: -0.124, -0.013), NO2: -0.139 (95% CI: -0.185, -0.092), and BC: -0.060 (95% CI: -0.115, -0.005). These associations were stronger for surrounding greenness at a greater distance from the schools (buffer 1230 m) PM2.5: -0.101 (95% CI: -0.156, -0.046) NO2: -0.122 (95% CI: -0.169, -0.075) BC: -0.080 (95% CI: -0.136, -0.026). These inverse associations were stronger after fully adjusting for regional pollution and meteorological conditions.

IMPACT STATEMENT

More than 90% of children under the age of 15 worldwide are exposed to elevated air pollution levels exceeding the WHO's guidelines. The study investigates the impact that urban infrastructure and greenness, in particular green areas and road proximity, have on indoor exposures to traffic-related PM2.5, NO2, and BC in inner-city schools. By examining a 10-year period the study provides insights for air quality management, into how road proximity and greenness at different buffers from the school locations can affect indoor exposure.

Residential radon decay products are associated with cough and phlegm in patients with COPD

Radon decay products attach to particulate matter (referred to as particle radioactivity, PR) has been shown to be potential to promote airway damage after inhalation. In this study, we investigated associations between PR with respiratory symptoms and health-related quality of life (HRQL) in patients with COPD. 141 male patients with COPD, former smokers, completed the St. George's Respiratory Questionnaire (SGRQ) after up to four 1-week seasonal assessments (N=474) of indoor (home) and ambient (central site) particulate matter ≤ 2.5 µm in diameter (PM2.5) and black carbon (BC). Indoor PR was measured as α-activity (radiation) on PM2.5 filter samples. The ratio of indoor/ambient sulfur in PM2.5 (a ventilation surrogate) was used to estimate α-PR from indoor radon decay. SGRQ responses assessed frequent cough, phlegm, shortness of breath, wheeze, and chest attacks in the past 3 months. Multivariable linear regression with generalized estimating equations accounting for repeated measures was used to explore associations, adjusting for potential confounders. Median (IQR) indoor α-PR was 1.22 (0.62) mBq/m3. We found that there were positive associations between α-PR with cough and phlegm. The strongest associations were with estimated α-PR of indoor origin for cough (31.1 % increase/IQR, 95 %CI: 8.8 %, 57.8 %), and was suggestive for phlegm (13.0 % increase/IQR, 95 %CI: -2.5 %, 31.0 %), similar adjusting for indoor BC or PM2.5. α-PR of indoor origin was positively associated with an increase in SGRQ Symptoms score [1.2 units/IQR; 95 %CI: -0.3, 2.6] that did not meet conventional levels of statistical significance. Our results suggested that exposure to indoor radon decay products measured as particle radioactivity, a common indoor exposure, is associated with cough, and suggestively associated with phlegm and worse HRQL symptoms score in patients with COPD.

The Impact of COVID-19 Health Measures on Adults With Multiple Chemical Sensitivity: Cross-Sectional Study

BACKGROUND

Multiple chemical sensitivity (MCS) develops in response to repeated small-level chemical exposures or a major exposure in a subset of people, who then experience symptoms that can range from mild to debilitating when exposed to chemicals. The arrival of the COVID-19 pandemic and the stringent health measures put in place may have increased the burden for those living with MCS, as it became more challenging to avoid chemicals that trigger their condition.

OBJECTIVE

This study aimed to better understand the lived experience of Canadians living with MCS during the first year of the COVID-19 pandemic.

METHODS

An online questionnaire was created to ask participants to compare daily living during the pandemic to before March 11, 2020. Data were collected in January and February 2021. Three areas were investigated: (1) environmental exposures to chemical triggers from ambient air (pollution from industry, farming, and traffic) and indoor air (the smell of cleaning products, cooking odors, and smoke); (2) access to, and satisfaction with, health care visits; and (3) how people experiencing MCS rated contact with their social network.

RESULTS

In all, 119 Canadians who had lived with MCS for more than a year completed the questionnaire. The participant sample was mostly female (86.6%, n=103) and highly educated, with 57.1% (n=68) having a university degree. Slightly more than half (57.1%, n=68) were older than 55 years. McNemar chi-square and Wilcoxon signed rank tests were used to evaluate if there were statistically significant changes before ("prepandemic period") and after ("postpandemic period") March 11, 2020. Perceived exposure to pollution from a highway or a road was significantly decreased from the prepandemic to postpandemic period (z=-3.347; P<.001). Analysis of industry or power plants also suggested a significant decrease in the perceived exposure from the prepandemic to postpandemic period (z=-2.152; P=.04). Participants reported an increase in exposure to odors from disinfectants or sanitizers that entered their living environment (P<.001). There was a significant decrease between prepandemic and postpandemic levels of satisfaction when attending in-person meetings with a physician (z=-2.048; P=.04), yet there were no significant differences between prepandemic and postpandemic levels of satisfaction for online or telephone meetings with a physician. Although people with MCS experienced increased social isolation (P<.001), they also reported an increase in understanding from family (P=.03) and a decrease in stigma for wearing personal protective equipment (P<.001).

CONCLUSIONS

During the first year of the COVID-19 pandemic, people with MCS were impacted by inaccessibility, loss of social support, and barriers to accessing health care. This study highlights unique challenges and possible benefits associated with the COVID-19 pandemic public health measures for individuals living with MCS. These findings can guide decision makers to improve policies on accessibility through appropriate accommodation measures.

Indoor and ambient black carbon and fine particulate matter associations with blood biomarkers in COPD patients

BACKGROUND

Systemic inflammation contributes to cardiovascular risk and chronic obstructive pulmonary disease (COPD) pathophysiology. Associations between systemic inflammation and exposure to ambient fine particulate matter (PM ≤ 2.5 μm diameter; PM2.5), and black carbon (BC), a PM2.5 component attributable to traffic and other sources of combustion, infiltrating indoors are not well described.

METHODS

Between 2012 and 2017, COPD patients completed in-home air sampling over one-week intervals, up to four times (seasonally), followed by measurement of plasma biomarkers of systemic inflammation, C-reactive protein (CRP) and interleukin-6 (IL-6), and endothelial activation, soluble vascular adhesion molecule-1 (sVCAM-1). Ambient PM2.5, BC and sulfur were measured at a central site. The ratio of indoor/ambient sulfur in PM2.5, a surrogate for fine particle infiltration, was used to estimate indoor BC and PM2.5 of ambient origin. Linear mixed effects regression with a random intercept for each participant was used to assess associations between indoor and indoor of ambient origin PM2.5 and BC with each biomarker.

RESULTS

144 participants resulting in 482 observations were included in the analysis. There were significant positive associations between indoor BC and indoor BC of ambient origin with CRP [%-increase per interquartile range (IQR);95 % CI (13.2 %;5.2-21.8 and 11.4 %;1.7-22.1, respectively)]. Associations with indoor PM2.5 and indoor PM2.5 of ambient origin were weaker. There were no associations with IL-6 or sVCAM-1.

CONCLUSIONS

In homes of patients with COPD without major sources of combustion, indoor BC is mainly attributable to the infiltration of ambient sources of combustion indoors. Indoor BC of ambient origin is associated with increases in systemic inflammation in patients with COPD, even when staying indoors.

Different airborne particulates trigger distinct immune pathways leading to peanut allergy in a mouse model

BACKGROUND

Environmental exposure to peanut through non-oral routes is a risk factor for peanut allergy. Early-life exposure to air pollutants, including particulate matter (PM), is associated with sensitization to foods through unknown mechanisms. We investigated whether PM promotes sensitization to environmental peanut and the development of peanut allergy in a mouse model.

METHODS

C57BL/6J mice were co-exposed to peanut and either urban particulate matter (UPM) or diesel exhaust particles (DEP) via the airways and assessed for peanut sensitization and development of anaphylaxis following peanut challenge. Peanut-specific CD4+ T helper (Th) cell responses were characterized by flow cytometry and Th cytokine production. Mice lacking select innate immune signaling genes were used to study mechanisms of PM-induced peanut allergy.

RESULTS

Airway co-exposure to peanut and either UPM- or DEP-induced systemic sensitization to peanut and anaphylaxis following peanut challenge. Exposure to UPM or DEP triggered activation and migration of lung dendritic cells to draining lymph nodes and induction of peanut-specific CD4+ Th cells. UPM- and DEP-induced distinct Th responses, but both stimulated expansion of T follicular helper (Tfh) cells essential for peanut allergy development. MyD88 signaling was critical for UPM- and DEP-induced peanut allergy, whereas TLR4 signaling was dispensable. DEP-induced peanut allergy and Tfh-cell differentiation depended on IL-1 but not IL-33 signaling, whereas neither cytokine alone was necessary for UPM-mediated sensitization.

CONCLUSION

Environmental co-exposure to peanut and PM induces peanut-specific Tfh cells and peanut allergy in mice.

Indoor (residential) and ambient particulate matter associations with urinary oxidative stress biomarkers in a COPD cohort

OBJECTIVES

Oxidative stress contributes to chronic obstructive pulmonary disease (COPD) pathophysiology. Associations between indoor (residential) exposure to particulate matter ≤2.5 μm in diameter (PM2.5) and one of its components, black carbon (BC), and oxidative stress are ill-defined.

METHODS

Between 2012 and 2017, 140 patients with COPD completed in-home air sampling over one week intervals, followed by collection of urine samples to measure oxidative stress biomarkers, malondialdehyde (MDA), a marker of lipid peroxidation, and 8-hydroxy-2' -deoxyguanosine (8-OHdG), a marker of oxidative DNA damage. Ambient (central site) BC and PM2.5 were measured, and the ratio of indoor/ambient sulfur in PM2.5, a surrogate for residential ventilation and particle infiltration, was used to estimate indoor BC and PM2.5 of outdoor origin. Mixed effects linear regression models with a participant-specific random intercept were used to assess associations with oxidative biomarkers, adjusting for personal characteristics.

RESULTS

There were positive associations (% increase per IQR; 95 % CI) of directly measured indoor BC with total MDA (6.96; 1.54, 12.69) and 8-OHdG (4.18; -0.67, 9.27), and similar associations with both indoor BC of outdoor origin and ambient BC. There were no associations with directly measured indoor PM2.5, but there were positive associations between indoor PM2.5 of outdoor origin and total MDA (5.40; -0.91, 12.11) and 8-OHdG (8.02; 2.14, 14.25).

CONCLUSIONS

In homes with few indoor combustion sources, directly measured indoor BC, estimates of indoor BC and PM2.5 of outdoor origin, and ambient BC, were positively associated with urinary biomarkers of oxidative stress. This suggests that the infiltration of particulate matter from outdoor sources, attributable to traffic and other sources of combustion, promotes oxidative stress in COPD patients.

Neurological susceptibility to environmental exposures: pathophysiological mechanisms in neurodegeneration and multiple chemical sensitivity

The World Health Organization lists air pollution as one of the top five risks for developing chronic non-communicable disease, joining tobacco use, harmful use of alcohol, unhealthy diets and physical inactivity. This review focuses on how host defense mechanisms against adverse airborne exposures relate to the probable interacting and overlapping pathophysiological features of neurodegeneration and multiple chemical sensitivity. Significant long-term airborne exposures can contribute to oxidative stress, systemic inflammation, transient receptor subfamily vanilloid 1 (TRPV1) and subfamily ankyrin 1 (TRPA1) upregulation and sensitization, with impacts on olfactory and trigeminal nerve function, and eventual loss of brain mass. The potential for neurologic dysfunction, including decreased cognition, chronic pain and central sensitization related to airborne contaminants, can be magnified by genetic polymorphisms that result in less effective detoxification. Onset of neurodegenerative disorders is subtle, with early loss of brain mass and loss of sense of smell. Onset of MCS may be gradual following long-term low dose airborne exposures, or acute following a recognizable exposure. Upregulation of chemosensitive TRPV1 and TRPA1 polymodal receptors has been observed in patients with neurodegeneration, and chemically sensitive individuals with asthma, migraine and MCS. In people with chemical sensitivity, these receptors are also sensitized, which is defined as a reduction in the threshold and an increase in the magnitude of a response to noxious stimulation. There is likely damage to the olfactory system in neurodegeneration and trigeminal nerve hypersensitivity in MCS, with different effects on olfactory processing. The associations of low vitamin D levels and protein kinase activity seen in neurodegeneration have not been studied in MCS. Table 2 presents a summary of neurodegeneration and MCS, comparing 16 distinctive genetic, pathophysiological and clinical features associated with air pollution exposures. There is significant overlap, suggesting potential comorbidity. Canadian Health Measures Survey data indicates an overlap between neurodegeneration and MCS (p < 0.05) that suggests comorbidity, but the extent of increased susceptibility to the other condition is not established. Nevertheless, the pathways to the development of these conditions likely involve TRPV1 and TRPA1 receptors, and so it is hypothesized that manifestation of neurodegeneration and/or MCS and possibly why there is divergence may be influenced by polymorphisms of these receptors, among other factors.

Quantifying factors affecting contributions of roadway exhaust and non-exhaust emissions to ambient PM10-2.5 and PM2.5-0.2 particles

Traffic-related particulate matter (PM) plays an important role in urban air pollution. However, sources of urban pollution are difficult to distinguish. This study utilises a mobile particle concentrator platform and statistical tools to investigate factors affecting roadway ambient coarse particle (PM_10-2.5) and fine particle (PM_2.5-0.2) concentrations in greater Boston, USA. Positive matrix factorization (PMF) identified six PM_10-2.5 sources (exhaust, road salt, brake wear, regional pollution, road dust resuspension and tyre-road abrasion) and seven fine particle sources. The seven PM_2.5-0.2 sources include the six PM_10-2.5 sources and a source rich in Cr and Ni. Non- exhaust traffic-related sources together accounted for 65.6% and 29.1% of the PM_10-2.5 and PM_2.5-0.2 mass, respectively. While the respective contributions of exhaust sources were 10.4% and 20.7%. The biggest non-exhaust contributor in the PM_10-2.5 was road dust resuspension, accounting for 29.6%, while for the PM_2.5-0.2, the biggest non-exhaust source was road-tyre abrasion, accounting for 12.3%. We used stepwise general additive models (sGAMs) and found statistically significant (p < 0.05) effects of temperature, number of vehicles and rush hour periods on exhaust, brake wear, road dust resuspension and road-tyre abrasion with relative importance between 19.1 and 62.2%, 12.5-42.1% and 4.4-42.2% of the sGAM model's explained variability. Speed limit and road type were also important factors for exhaust, road-tyre and brake wear sources. Meteorological variables of wind speed and relative humidity were significantly associated with both coarse and fine road dust resuspension and had a combined relative importance of 38% and 48%. The quantifying results of the factors that influence traffic-related sources can offer key insights to policies aiming to improve near-road air quality.

Factors Influencing Classroom Exposures to Fine Particles, Black Carbon, and Nitrogen Dioxide in Inner-City Schools and Their Implications for Indoor Air Quality

BACKGROUND

School classrooms, where students spend the majority of their time during the day, are the second most important indoor microenvironment for children.

OBJECTIVE

We investigated factors influencing classroom exposures to fine particulate matter (PM2.5), black carbon (BC), and nitrogen dioxide (NO2) in urban schools in the northeast United States.

METHODS

Over the period of 10 y (2008-2013; 2015-2019) measurements were conducted in 309 classrooms of 74 inner-city schools during fall, winter, and spring of the academic period. The data were analyzed using adaptive mixed-effects least absolute shrinkage and selection operator (LASSO) regression models. The LASSO variables included meteorological-, school-, and classroom-based covariates.

RESULTS

LASSO identified 10, 10, and 11 significant factors (p<0.05) that were associated with indoor PM2.5, BC, and NO2 exposures, respectively. The overall variability explained by these models was R2=0.679, 0.687, and 0.621 for PM2.5, BC, and NO2, respectively. Of the model's explained variability, outdoor air pollution was the most important predictor, accounting for 53.9%, 63.4%, and 34.1% of the indoor PM2.5, BC, and NO2 concentrations. School-based predictors included furnace servicing, presence of a basement, annual income, building type, building year of construction, number of classrooms, number of students, and type of ventilation that, in combination, explained 18.6%, 26.1%, and 34.2% of PM2.5, BC, and NO2 levels, whereas classroom-based predictors included classroom floor level, classroom proximity to cafeteria, number of windows, frequency of cleaning, and windows facing the bus area and jointly explained 24.0%, 4.2%, and 29.3% of PM2.5, BC, and NO2 concentrations, respectively.

DISCUSSION

The adaptive LASSO technique identified significant regional-, school-, and classroom-based factors influencing classroom air pollutant levels and provided robust estimates that could potentially inform targeted interventions aiming at improving children's health and well-being during their early years of development. https://doi.org/10.1289/EHP10007.

Epigenetic regulation is involved in traffic-related PM2.5 aggravating allergic airway inflammation in rats

Increasing fine particulate matter (PM_2.5) and epigenetic modifications are closely associated with the pathogenesis of asthma, but the definite mechanism remains unclear. The traffic-related PM_2.5 exposure aggravated pulmonary inflammation and changed the methylation level of interferon gamma (Ifng) and interleukin (Il)4 genes, and then altered levels of affiliated cytokines of IFN-γ and IL-4 in rats with allergic airway inflammation. It also increased the level of miR146a and decreased the level of miR31. In addition, transcription factors of nuclear factor kappa B (NF-κB) and signal transducer and activator of transcription 6 (Stat6) rose; forkhead box P3 (Foxp3) and signal transducer and activator of transcription 4 (Stat4) lowered. The traffic-related PM_2.5 altered epigenetic modifications in allergic airway inflammation of rats leading to inflammation exacerbation through impaired regulatory T (Treg) cells function and T-helper type 1 (Th1)/Th2 cells imbalance, which provided a new target for the treatment and control of asthma.

The Influence of Traffic-Related Air Pollution (TRAP) in Primary Schools and Residential Proximity to Traffic Sources on Histone H3 Level in Selected Malaysian Children

This study aimed to investigate the association between traffic-related air pollution (TRAP) exposure and histone H3 modification among school children in high-traffic (HT) and low-traffic (LT) areas in Malaysia. Respondents' background information and personal exposure to traffic sources were obtained from questionnaires distributed to randomly selected school children. Real-time monitoring instruments were used for 6-h measurements of PM₁₀, PM_2.5, PM₁, NO₂, SO₂, O₃, CO, and total volatile organic compounds (TVOC). Meanwhile, 24-h measurements of PM_2.5-bound black carbon (BC) were performed using air sampling pumps. The salivary histone H3 level was captured using an enzyme-linked immunosorbent assay (ELISA). HT schools had significantly higher PM₁₀, PM_2.5, PM₁, BC, NO₂, SO₂, O₃, CO, and TVOC than LT schools, all at p < 0.001. Children in the HT area were more likely to get higher histone H3 levels (z = -5.13). There were positive weak correlations between histone H3 level and concentrations of NO₂ (r = 0.37), CO (r = 0.36), PM₁ (r = 0.35), PM_2.5 (r = 0.34), SO₂ (r = 0.34), PM₁₀ (r = 0.33), O₃ (r = 0.33), TVOC (r = 0.25), and BC (r = 0.19). Overall, this study proposes the possible role of histone H3 modification in interpreting the effects of TRAP exposure via non-genotoxic mechanisms.

Effects of particulate matter gamma radiation on oxidative stress biomarkers in COPD patients

Inhalation of particulate matter (PM) radioactivity is an important pathway of ionizing radiation exposure. We investigated the associations between short-term exposures to PM gamma radioactivity with oxidative stress in COPD patients. Urinary concentrations of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and malondialdehyde (MDA) of 81 COPD patients from Eastern Massachusetts were measured 1-4 times during 2012-2014. Daily ambient and indoor PM gamma activities (gamma-3 through gamma-9) were calculated based on EPA RadNet data and indoor-outdoor infiltration ratios. Linear mixed-effects models were used to examine the associations between biomarkers with PM gamma activities for moving averages from urine collection day to 7 days before. Our results indicate that ambient and indoor PM gamma activities were positively associated with 8-OHdG, with stronger effects for exposure windows closer to urine collection day. For per interquartile range increase in indoor PM gamma activities averaged over urine collection day and 1 day before, 8-OHdG increased from 3.41% (95% CI: -0.88, 7.88) to 8.87% (95% CI: 2.98, 15.1), adjusted for indoor black carbon. For MDA, the timing of greatest effects across the exposure week varied but was nearly all positive. These findings provide insight into the toxigenic properties associated with PM radioactivity and suggest that these exposures promote systemic oxidative stress.

Toxic metals in outdoor/indoor airborne PM2.5 in port city of Northern, China: Characteristics, sources, and personal exposure risk assessment

Outdoor and indoor PM_2.5 samples were simultaneously collected over four seasons (2017-2018) in Caofeidian, China, and analyzed for 15 elements to investigate the characteristics, sources, and health risks of PM_2.5-bound metals. Source-specific PM_2.5-bound metals were analyzed using positive matrix factorization, combined with the conditional probability function and potential source contribution function model. The health risks were evaluated using the health risk assessment model, which included the exposure parameters of indoor and outdoor activities of Chinese residents. The annual median of PM_2.5 concentrations (89.68 μg/m³) and total metals (2.67 μg/m³) from the outdoor samples significantly surpassed that of the indoor samples (51.56 μg/m³) and total metals (1.51 μg/m³) (P < 0.05). In addition, the indoor/outdoor concentration ratios indicated that most indoor metals mainly originated from outdoor emission sources. In the annual analysis of PM_2.5-bound metal sources, this study identified five metal sources: coal combustion, resuspended dust, traffic emissions, fuel combustion sources, and industrial sources, among which industry sources (36.6%) contributed the most. The non-carcinogenic risks of metals for adults (2.81) and children (2.80) all exceed the acceptable non-carcinogenic risk level (1). The non-carcinogenic risk of Mn (1.46 for children, 1.48 for adults) was a key factor in the total non-carcinogenic risk. The total carcinogenic risk of metals for children (3.75 × 10^-5) was above the acceptable level (1.0 × 10^-6) but within the tolerant limit (1.0 × 10^-4), and that for adults (1.48 × 10^-4) was above the tolerant limit. The lifetime carcinogenic risk of Cr⁶⁺ had the highest proportion of the total carcinogenic risk for children (87.5%) and adults (87.8%). Our results revealed that both adults and children suffered carcinogenic and non-carcinogenic risks from the PM_2.5-bound metals in Caofeidian. The corresponding emission control measures of metals in atmosphere should be considered.

Sources of indoor PM2.5 gross α and β activities measured in 340 homes

Particle radioactivity (PR) exposure has been linked to adverse health effects. PR refers to the presence of α- and β-emitting radioisotopes attached to fine particulate matter (PM_2.5). This study investigated sources contributing to indoor PM_2.5 gross α- and β-radioactivity levels. We measured activity from long-lived radon progeny radionuclides from archived PM_2.5 samples collected in 340 homes in Massachusetts during the period 2006-2010. We analyzed the data using linear mixed effects models and positive matrix factorization (PMF) analysis. Indoor PM_2.5 gross α-activity levels were correlated with sulfur (S), iron (Fe), bromine (Br), vanadium (V), sodium (Na), lead (Pb), potassium (K), calcium (Ca), silicon (Si), zinc (Zn), arsenic (As), titanium (Ti), radon (²²²Rn) and black carbon (BC) concentrations (p <0.05). Indoor PM_2.5 β-activity was correlated with S, As, antimony (Sb), Pb, Br and BC. We identified four indoor PM_2.5 sources: outdoor air pollution (62%), salt aerosol source (14%), fireworks and environmental tobacco smoke (7%) and indoor mixed dust (17%). Outdoor air pollution was the most significant contributor to indoor PM_2.5 α- and β-activity levels. The contributions of this source were during the summer months and when windows were open. Indoor mixed dust was also found to contribute to PM_2.5 α-activity. PM_2.5 α-activity was further associated with radon during winter months, showing radon's important role as an indoor source of ionizing radiation.

Trace element concentrations in ambient air as a function of distance from road

Traffic-related air pollution is associated with various adverse health effects. In the absence of more complicated exposure assessment techniques, many environmental health studies have used the natural logarithm of distance to road as a proxy for traffic-related exposures. However, research validating this proxy and further explaining the spatial patterns and elemental composition of traffic-related particulate matter air pollution remains limited. In this study, we collected air samples using a mobile particle concentrator that allowed for high sample loading from major roadways in the Greater Boston Area. We found that concentrations of Cl, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Sr, Zr, Sn, Ba, and Pb were significantly associated with the natural logarithm of distance to road in coarse particulate matter, and total fine particulate mass concentrations of Al, Ca, Ti, Cr, Mn, Fe, Cu, and Zn were significantly associated with natural logarithm of distance to road in fine particulate matter. Road type (A1 or A2 [primary roads or highways] versus A3 [secondary and connecting roads]) was not a significant predictor of any traffic-related elements in particulate matter air pollution. Our results help identify traffic-related elements in particulate matter air pollution and support the use of logarithm of distance to road as a proxy for traffic-related particulate matter air pollution exposure assessment in epidemiological studies.

Measurement of the gross alpha activity of the fine fractions of road dust and near-roadway ambient particle matter

Traffic-related air pollution, including direct exhaust emissions and road dust (RD), impacts individuals living near busy roads. We recently conducted a study to investigate the sources and composition of tailpipe and non-tailpipe traffic emissions, where we collected and analyzed samples of ambient air fine particulate matter (PM_2.5) and fine RD (RD_2.5) at different distances from major roadways. We analyzed a subset of the samples, including those collected at the roadside and local background, for their alpha activity level. Subsequently, we investigated whether there is a distance-related decay in the alpha activity in RD_2.5 or PM_2.5 similar to those observed for traffic-related species in PM_2.5 and RD_2.5. We found that the alpha activity of ambient air PM_2.5 (Bq/mg) was more than an order of magnitude higher than the activity level of the corresponding RD_2.5 sample, suggesting that PM_2.5 may be more toxic than RD_2.5. Using mixed-effects regression models, we found that ambient PM_2.5 alpha activity was significantly higher during the cold months than during warm months, and that the background was higher than the roadside (though not significantly). In contrast, the RD_2.5 alpha activity was significantly higher at the background site compared to the roadside but was not significantly affected by season. In addition to sampling position, both Zn and elemental carbon (EC) were significant predictors of RD_2.5 alpha activity. In addition, the roadside RD_2.5 activity levels were found to be higher at highways as compared to secondary roads. While traffic-related emissions do not appear to be significant sources of either ambient PM_2.5 or RD_2.5 alpha activity, the RD_2.5 results suggest that traffic-related particles may contribute to RD_2.5 alpha-activity. Implications: Many studies have reported the effects of traffic-related particulate matter (PM) on human health, and there is growing interest in the health effects of exposure to environmental PM alpha activity. This is the first study to report on the alpha activity of road dust (RD) or near-roadway ambient PM. We found that the alpha activity of ambient PM is twenty times higher than RD, suggesting that ambient PM may be more toxic. In PM and RD, the alpha activities were higher at background sites than at the roadside, indicating that traffic-related emissions are not a significant source of particulate radioactivity.

Development and evaluation of a mobile laboratory for collecting short-duration near-road fine and coarse ambient particle and road dust samples

This study used fine and coarse PM concentrator technology in a Mobile Particle Concentrator Platform (MPCP) designed and built to allow the collection of large amounts of ambient PM, enabling time-resolved speciation analysis, which would not be feasible using conventional methods. One hour of sampling yielded sufficient sample loading for trace elemental analysis using X-Ray Fluorescence (XRF). In addition, we developed a novel Road Dust Aerosolizer (RDA) sampler in order to collect PM_2.5 and PM₁₀ surface road dust in situ. This sampler aerosolizes dust from the road surface, simulating ambient road dust resuspension, resulting in measured PM composition and size more appropriately (and less labor-intensive) than those obtained from studies using bulk road dust sieved and re-suspended in the laboratory. Overall, our modified fine and coarse particle concentrators yielded good reproducibility between co-located samples and sufficient loading for trace elemental analysis. For particle mass concentration, we observed a relative error of 3% and 4% among pairs of filters for fine and coarse concentrators, respectively; confirming that the mass collected on an unweighted quartz filter in parallel with a Teflon filter will have the same PM mass as the weighed Teflon filter. For samples with elements that are well above the LOD, relative uncertainty values were between 5% and 10% for the fine and 3% and 10% for the coarse. Our results show that the RDA system has an excellent precision for mass and elements as well. The relative error for mass is 7% for PM₁₀ and 3% for PM_2.5 within pairs and ranged from 2 to10% for elements. In conclusion, we developed a method for collecting PM₁₀ and PM_2.5 near-road air and surface road dust for short durations, which allows investigation of the composition of direct (airborne) and indirect (re-suspended road dust) non-tailpipe vehicular emissions. Implications: The methods we developed in this study allow the collection of one-hour PM10-2.5 and PM2.5-0.2 samples from near-road ambient air at several distances from the same roadway in 1 day, and collection of road dust directly from the road surface, with sufficient loading for trace elemental analysis. This will allow investigation of the composition of direct (airborne) and indirect (re-suspended road dust) vehicular emissions.

Trace element mass fractions in road dust as a function of distance from road

Road dust particles play an important role in atmospheric pollution and are associated with adverse human health effects. Traffic emissions are a major source of particles in road dust. However, there has been limited information about the relationship between distance from road and traffic-related elements levels in road dust. We investigated the relationships between proximity to the nearest major roadway and trace element mass fractions in PM₁₀ and PM_2.5 re-suspended from the road surface, based on measurements at three different distance ranges. We found that mass fractions of Ba, Cu, Zr, Zn, Cl, Co, Cr, Ca, Ti in PM₁₀ road dust as well as Zr, Cu, Cl, Zn, Cr, Ti, Mn, Ca, Ni, and Fe in PM_2.5 road dust, significantly decreased with distance from major road. Most of these elements are associated with road traffic emissions, including both tailpipe and non-tailpipe emissions. The decrease rates differed among elements due to differences in local traffic contributions. The decreases for elements which are mainly associated with non-tailpipe traffic emissions (e.g., Ba, Zr) were more dramatic. Our results indicate that traffic emissions, especially non-tailpipe emissions, contribute substantially to road dust, suggesting the need for control strategies for non-tailpipe emissions. Implications: We investigated the relationships between road proximity with trace element mass fractions in PM10 and PM2.5 re-suspended from the road surface. We observed significant decrease of traffic-related elements in PM10 and PM2.5 road dust with log distance from major road. We also found that the mass fractions for elements, which mainly come from traffic decrease more sharply compared to elements which come from both traffic and other sources. Our results indicate that traffic emissions contribute substantially to road dust, and imply that the distance to major road can be used as a proxy for ambient exposure.

Vehicle non-exhaust emissions - Revealing the pathways from source to environmental exposure

Brakes, tyres and road deposits have become important contributors to the overall particle emissions of vehicles globally, with constituents in these wear particles considered to be harmful to human health (PM₁₀ and PM_2.5). Previous research has documented mass/size distributions, physical and chemical characteristics, emission factors and long-term implications and environmental occurrences. The complex path these pollutants take from their origins to the environment, however, is not fully understood. This is partly owing to the breadth of spatio-temporal scales involved in the advection-diffusion processes (nanometers to meters, microseconds to minutes). These short timescale particle transport mechanisms impact human exposure, such as pedestrians and cyclists, and initiate the long-term interaction of these pollutants with other environmental compartments. Here, we present an analysis for urban driving conditions to highlight the opportunities to reveal these complex pathways and formulate opinions that aim to stimulate future enquiry. We describe important vehicular areas and exposure scenarios where efforts should focus. Future interdisciplinary research into these particle transport mechanisms must be prioritised as it can provide the foundation for developing urgently needed pollution control strategies, transport infrastructure layouts and transport policies that mitigate, or possibly eliminate pollution exposure risks.

Effect of Urban Greening on Incremental PM2.5 Concentration During Peak Hours

In China, severe haze is a major public health concern affecting residents' health and well-being. This study used hourly air quality monitoring data from 285 cities in China to analyze the effect of green coverage (GC) and other economic variables on the incremental PM_2.5 concentration (ΔPM_2.5) during peak hours. To detect possible non-linear and interaction effect between predictive variables, a kernel-based regularized least squares (KRLS) model was used for empirical analysis. The results show that there was considerable heterogeneity between cities regarding marginal effect of GC on ΔPM_2.5, which could potentially be explained by different seasons, latitude, urban maintenance expenditure (UE), real GDP per capita (PG), and population density (PD). Also described in this study, in cities with high UE, the growth of GC, PG, and PD always remain a positive impact on mitigation of haze pollution. This shows that government expenditure on urban maintenance can reduce or mitigate the environmental pollution from economic development. In addition, the influence of other urban elements on air quality had also been analyzed so that different combinations of mitigation policies are proposed for different regions in this study to meet the mitigation targets.

Short-term exposures to particulate matter gamma radiation activities and biomarkers of systemic inflammation and endothelial activation in COPD patients

BACKGROUND

We hypothesized that particulate matter (PM) gamma activity (gamma radiation associated with PM) is associated with systemic effects.

OBJECTIVE

Examine short-term relationships between ambient and indoor exposures to PM gamma activities with systemic inflammation and endothelial activation in chronic obstructive pulmonary disease (COPD) patients.

METHODS

In 85 COPD patients from Eastern Massachusetts, USA from 2012 to 2014, plasma C-reactive protein (CRP), interleukin-6 (IL-6), and soluble vascular cell adhesion molecule-1 (sVCAM-1) were measured seasonally up to four times. We used US EPA RadNet data measuring ambient gamma radiation attached to PM adjusted for background radiation, and estimated in-home gamma radiation exposures using the ratio of in-home-to-ambient sulfur in PM2.5. Linear mixed-effects regression models were used to determine associations between moving averages of PM gamma activities through the week before phlebotomy with these biomarkers. We explored ambient and indoor PM2.5, black carbon (BC), and NO2 as confounders.

RESULTS

Ambient and indoor PM gamma activities measured as energy spectra classes 3 through 9 were positively associated with CRP and IL-6. For example, averaged from phlebotomy day through previous 6 days, each IQR increase in indoor PM gamma activity for each spectra class, was associated with an CRP increase ranging from 7.45% (95%CI: 2.77, 12.4) to 13.4% (95%CI: 5.82, 21.4) and for ambient exposures were associated with an increase of 8.75% (95%CI: -0.57, 18.95) to 14.8% (95%CI: 4.5, 26.0). Indoor exposures were associated with IL-6 increase of 3.56% (95%CI: 0.31, 6.91) to 6.46% (95%CI:1.33, 11.85) and ambient exposures were associated with an increase of 0.03% (95%CI: -6.37, 6.87) to 3.50% (95%CI: -3.15, 10.61). There were no positive associations with sVCAM-1. Sensitivity analyses using two-pollutant models showed similar effects.

CONCLUSIONS

Our results demonstrate that short-term exposures to environmental PM gamma radiation activities were associated with systemic inflammation in COPD patients.

The concurrent decline of soil lead and children's blood lead in New Orleans

The inextricable link between topsoil lead (Pb) and children’s blood lead (BPb) has not been widely accepted. Pb is associated with multiple health adversities. Urban residents are at risk from exposure to legacy Pb dust in topsoil resulting from smelting, industrial discharges, leaded gasoline emissions, leaded paint, and incineration. In New Orleans, topsoil median Pb decreased in ∼15 y from 99 mg/kg to 54 mg/kg, or ∼2.4 mg⋅kg⋅y⁻¹. In ∼12 y, children’s median BPb declined from 3.6 μg/dL to 1.3 μg/dL, or ∼0.2 μg⋅dL⋅y⁻¹. We argue that depletion of topsoil Pb is an important factor in the continuous decline of children’s BPb. Similar processes are expected in all US cities. Primary prevention requires curtailing Pb in all sources, including topsoil.

Lead (Pb) is extremely toxic and a major cause of chronic diseases worldwide. Pb is associated with health disparities, particularly within low-income populations. In biological systems, Pb mimics calcium and, among other effects, interrupts cell signaling. Furthermore, Pb exposure results in epigenetic changes that affect multigenerational gene expression. Exposure to Pb has decreased through primary prevention, including removal of Pb solder from canned food, regulating lead-based paint, and especially eliminating Pb additives in gasoline. While researchers observe a continuous decline in children’s blood lead (BPb), reservoirs of exposure persist in topsoil, which stores the legacy dust from leaded gasoline and other sources. Our surveys of metropolitan New Orleans reveal that median topsoil Pb in communities (n = 274) decreased 44% from 99 mg/kg to 54 mg/kg (P value of 2.09 × 10⁻⁰⁸), with a median depletion rate of ∼2.4 mg⋅kg⋅y⁻¹ over 15 y. From 2000 through 2005 to 2011 through 2016, children’s BPb declined from 3.6 μg/dL to 1.2 μg/dL or 64% (P value of 2.02 × 10⁻⁸⁵), a decrease of ∼0.2 μg⋅dL⋅y⁻¹ during a median of 12 y. Here, we explore the decline of children’s BPb by examining a metabolism of cities framework of inputs, transformations, storages, and outputs. Our findings indicate that decreasing Pb in topsoil is an important factor in the continuous decline of children’s BPb. Similar reductions are expected in other major US cities. The most contaminated urban communities, usually inhabited by vulnerable populations, require further reductions of topsoil Pb to fulfill primary prevention for the nation’s children.

Multivariate spatial patterns of ambient PM2.5 elemental concentrations in Eastern Massachusetts

Understanding the factors that affect spatial differences in PM_2.5 composition is crucial for implementing emissions control and health policies. Although previous studies have explored modeling of spatial patterns as a tool to improve human exposure assessment, little work has employed a multivariate clustering approach to identify spatial patterns in particle composition. In this study, we used this approach to assess the spatial patterns of ambient PM_2.5 elemental concentrations in Eastern Massachusetts in the United States. To distinguish one cluster of sites from another, we considered air pollution sources and geodemographic variables. We evaluated spatial patterns for 11 elemental components of ambient PM_2.5, which included S, K, Ca, Fe, Zn, Cu, Ti, Al, Pb, V, and Ni. The analyses for S, Ca, Cu, Ti, Al, and Pb resulted in: 2 clusters for Fe, Zn, V, and Ni; 3 clusters; and for 12 clusters for K. Overall, our findings suggest substantial variation of clusters among PM_2.5 components. In addition, land use, population density, and daily traffic were used as variables to more effectively characterize clusters of sites. We used R² values to estimate the effectiveness of each variable in characterizing clusters. Larger R² values indicate better the discrimination among the sites. For example, population density had the highest R² value when the analysis was performed for S, Ca, Zn, Ti, Al, Pb, and V; land use presented the highest R² value for Cu, V, and Ni; and, traffic showed the highest R² value for PM_2.5 mass concentration. This study improves the ability to model both the between- and within-area variability of source emissions and pollution regime, using concentrations of PM_2.5 components.

Synthesis of Harvard Environmental Protection Agency (EPA) Center studies on traffic-related particulate pollution and cardiovascular outcomes in the Greater Boston Area

The association between particulate pollution and cardiovascular morbidity and mortality is well established. While the cardiovascular effects of nationally regulated criteria pollutants (e.g., fine particulate matter [PM_2.5] and nitrogen dioxide) have been well documented, there are fewer studies on particulate pollutants that are more specific for traffic, such as black carbon (BC) and particle number (PN). In this paper, we synthesized studies conducted in the Greater Boston Area on cardiovascular health effects of traffic exposure, specifically defined by BC or PN exposure or proximity to major roadways. Large cohort studies demonstrate that exposure to traffic-related particles adversely affect cardiac autonomic function, increase systemic cytokine-mediated inflammation and pro-thrombotic activity, and elevate the risk of hypertension and ischemic stroke. Key patterns emerged when directly comparing studies with overlapping exposure metrics and population cohorts. Most notably, cardiovascular risk estimates of PN and BC exposures were larger in magnitude or more often statistically significant compared to those of PM_2.5 exposures. Across multiple exposure metrics (e.g., short-term vs. long-term; observed vs. modeled) and different population cohorts (e.g., elderly, individuals with co-morbidities, young healthy individuals), there is compelling evidence that BC and PN represent traffic-related particles that are especially harmful to cardiovascular health. Further research is needed to validate these findings in other geographic locations, characterize exposure errors associated with using monitored and modeled traffic pollutant levels, and elucidate pathophysiological mechanisms underlying the cardiovascular effects of traffic-related particulate pollutants. Implications: Traffic emissions are an important source of particles harmful to cardiovascular health. Traffic-related particles, specifically BC and PN, adversely affect cardiac autonomic function, increase systemic inflammation and thrombotic activity, elevate BP, and increase the risk of ischemic stroke. There is evidence that BC and PN are associated with greater cardiovascular risk compared to PM_2.5. Further research is needed to elucidate other health effects of traffic-related particles and assess the feasibility of regulating BC and PN or their regional and local sources.

Curtailing Lead Aerosols: Effects of Primary Prevention on Declining Soil Lead and Children's Blood Lead in Metropolitan New Orleans

After decades of accumulation of lead aerosols in cities from additives in gasoline, in 1975 catalytic converters (which are ruined by lead) became mandatory on all new cars. By 1 January 1986 the rapid phase-down banned most lead additives. The study objective is to review temporal changes of environmental lead and children's blood lead in communities of metropolitan New Orleans. In 2001, a soil lead survey of 287 census tracts of metropolitan New Orleans was completed. In August-September 2005 Hurricanes Katrina and Rita storm surges flooded parts of the city with sediment-loaded water. In April-June 2006, 46/287 (16%) of the original census tracts were selected for resurvey. A third survey of 44/46 (15%) census tracts was completed in 2017. The census tract median soil lead and children's median blood lead decreased across surveys in both flooded and unflooded areas. By curtailing a major urban source of lead aerosols, children's lead exposure diminished, lead loading of soil decreased, and topsoil lead declined. Curtailing lead aerosols is essential for primary prevention. For the sake of children's and ultimately societal health and welfare, the long-term habitability of cities requires terminating all remaining lead aerosols and cleanup of legacy-lead that persists in older inner-city communities.