Ultrafine Particle Concentrations Research Articles

Preterm Birth among Infants Exposed to In Utero Ultrafine Particle Emissions from Aircraft Engines near the Los Angeles International Airport

Ambient air pollution is a known risk factor for adverse birth outcomes, but the role of ultrafine particles (UFPs) is not yet well understood. UFP emissions from aircraft are spread across large residential areas downwind of airports, possibly causing a considerable reproductive health burden.Birth certificate data from the California Department of Public Health was drawn from all births by mothers living in a 200 mi2 area downwind of Los Angeles International Airport (LAX) in 2011 (n=16,268). These records were used to ascertain the presence preterm birth (PTB), as well as maternal covariate information. To assess in utero exposure to UFPs, we input geocoded maternal addresses into a novel geospatial UFP dispersion model that has been validated by extensive ground-level measurements near LAX.We used multiple logistic regression, regressing PTB (live birth < 37 weeks gestation) on UFP concentrations estimated from the dispersion model. We adjusted for maternal factors like age, educational attainment, and race/ethnicity. We further adjusted for measures of air pollution from other sources, like traffic, including PM2.5, nitrogen oxides, and surface ozone to isolate the role of aircraft-related UFPs. An interaction term between UFPs and maternal nativity was included in the model.Among this birth cohort, we found an 11% increase in odds (95% CI: 1.01, 1.22) of PTB per interquartile range of UFP exposure. When stratified by maternal nativity, no increase in PTB among infants of foreign-born mothers was detected (OR = 1.02, 95% CI: 0.90, 1.16) but was detected among infants of US-born women (OR = 1.19, 95% CI: 1.06, 1.32). Effect modification by nativity was borderline statistically significant (p = 0.04).We found increased exposure to aircraft-related UFPs was associated with an elevated risk of PTB, serving as evidence of the reproductive health effects of UFP exposures from aircraft emissions. However, this relationship appears to be modified by maternal nativity.

A Crossover Study of In-Vehicle Air Filtration and Acute Changes in Heart Rate Variability and Cognition among Healthy Adults

Background: Traffic-related air pollutants (TRAP) are known to negatively affect cardiovascular health, and personal exposures may be highest during rush hour commutes. We examined the effectiveness of cabin air filtration at reducing in-vehicle exposures to TRAP, and whether these exposures were associated with short term changes in heart rate variability (HRV) and cognition in healthy adults.Methods: A crossover study of cabin air filtration and in-cabin exposure to TRAP was conducted in Montreal, Canada in 2014. Forty-eight participants were exposed to TRAP during two separate commutes of approximately 90 minutes: one trip with an electrostatic cabin air filter and one trip without a cabin air filter. In-vehicle and outdoor rooftop measures of ultrafine particles (UFPs), fine particle matter (PM2.5), black carbon (BC), nitrogen dioxide (NO2), and volatile organic compounds (VOCs) were collected during the commute. HRV parameters were measured before, during, and after each exposure period. Linear mixed effects models were used to examine relationships between in-cabin air pollution concentrations and changes in time and frequency domain measures of HRV.Results: The cabin air filter reduced in-vehicle UFP concentrations by 28%, (mean difference= 26,232/cm3, 95% CI: 11,733-40,730), PM2.5 by 30% (mean difference= 6 ug/m3 95% CI: 5-8), and BC by 32% (mean difference= 1,348 ng/m3 95% CI: -1,654-1,042 ng/m3). The air filter did not reduce in-vehicle concentrations of NO2 or VOCs. In general, cabin air filtration was not consistently associated with changes in HRV. PM2.5, UFPs and BC were positively associated with changes in both time and frequency-domain measures of HRV during and after the commute; these associations tended to be stronger among women.Conclusions: Electrostatic cabin air filters can lower in-vehicle exposures to TRAP, particularly those pollutants produced in high concentrations by diesel vehicle traffic, and may modify acute cardiac effects of TRAP.

Sensor Selection and Scaling Up Mobile Monitoring for High-Resolution Mapping of Community Air Quality: Design Considerations in the MOV-UP Airport Ultrafine Particle Study

As novel environmental monitoring and exposure sensing approaches evolve, there is still the need to match the air quality concerns of communities with appropriate measurements. Designing an appropriate measurement approach for exposure studies requires identifying the sources of greatest concern, the set of pollutants that best characterize these sources, and sampling in manner that quantifies variations in concentrations in space and time. Recently, for the new Mobile Observations of Ultrafine Particles (MOV-UP) study, a sampling plan was designed to characterize ultrafine particle levels in communities near the SeaTac International Airport in Seattle, WA.Because of the need to cover a large area of approximately 250 km2 with a limited instrument and staffing budget within the timeframe of a year, a mobile monitoring approach was chosen, in which two instrumented vehicles would collect ultrafine particle measurements along local roads that transect the flight paths of the airport. Mobile monitoring would allow coverage of the large area with a relatively small number of high-end ultrafine particle counters.In addition to measuring ultrafine particle concentrations for the MOV-UP study, there was also a need to distinguish between ultrafines sourced from roadway traffic versus those from aircraft. GPS data were used to identify driving on major roadways, and were supplemented by additional measurements of ultrafine particle size and black carbon levels to help discriminate between roadway and aircraft sources. A principal component analysis (PCA) yielded multivariate eigenvalues representative of the different sources of concern. Also, relating flight patterns with wind patterns may also help to identify ultrafine particle levels attributable to aircraft.

The Mobile Observations of Ultrafine Particles (MOV-UP) Study: Winter 2018 Sampling

The Mobile ObserVations of Ultrafine Particles (MOV-UP) Study is a two-year project intended to quantify air quality impacts of air traffic for communities located near, and below the flight paths of the SeaTac airport. The study aims to assess ultrafine particle concentrations within 10 miles of the airport in the directions of aircraft take-offs and landings over the course of 4 seasons. To date, sampling has been completed for Winter 2018. Over this time period, 16 days of mobile sampling were conducted using a suite of mobile instruments capable of detecting particles between 10-20, 20-36 and >36 nm in diameter on a 10 second time-scale. Black carbon (BC) particle concentration was collected on the 10 second scale as well as the full range of particle size distribution from 10 nm to 1 µm on the 1 minute time scale. The mean wind direction during the drives was from the SW. There were two days with wind from the NW, which resulted in reversal of the landing and take-off direction at the airport. A varimax rotated principal component analysis was performed on the 1 minute particle size distribution data and BC concentration, normalized to total particle count. Three components accounted for 74% of the variance observed. The first component, explaining 33% of the variance, shows high loadings of particles with median diameter of less than 20.5 nm. The second component, explaining 23% of the variance, shows high loadings of particles with median diameter of greater than 20.5 nm. The third component, explaining 18% of the variance, shows high proportion of black carbon. The geographic distribution of the component scores suggests that the first component is associated with the aircraft flight path. This study demonstrates the ability of mobile monitoring to detect variations in on-road particle size distribution that may be associated not only with vehicular traffic, but also with distance to flight path within 10 miles of an urban airport.

Role of anthropogenic emissions and meteorology on ultrafine particle bursts over a high altitude site in Western Ghats during pre-monsoon

The ultrafine particle number concentration and size distribution during pre-monsoon (spring) over a high altitude location, Ooty (11.3 °N, 74.4 °E, 2240 m amsl) in Western Ghats, the highest peak in South India, are examined using campaign based ground observations. The total number concentrations are in the range ∼1000–3000 cm−3 with significant increase (2–4 folds) during the periods of ultrafine particle (UFP) (diameter < 100 nm) bursts. The UFP burst happens mostly during afternoon/evening with significant enhancement in number concentrations of nucleation (Nnuc) and Aitken (NAitk) mode particles. Examination of the association of these events with prevailing meteorology and trace gas concentrations revealed weaker dependence in general. However, the association between NOX and the UFP concentration indicates the possibility of common source for both. During the high concentrations of UFP, local winds originated predominantly from south/south west directions of the study location where the valley region with significant anthropogenic activities is located. Time of occurrence of the UFP bursts, trace gas concentrations and direction of the winds points towards the role of valley winds in transporting plume of pollutants to the mountain top observatory during the daytime.

Nanoparticle Emissions and GPF for MPI Gasoline Cars

Further efforts to reduce the air pollution from traffic are undertaken worldwide and the filtration of exhaust gas will also be increasingly applied on gasoline cars (GPF) … gasoline particle filter).In the present paper, some results of investigations of nanoparticles from four MPI gasoline cars are represented. The measurements were performed at vehicle tailpipe and in CVS-tunnel. Moreover, two variants of GPF were investigated on a high-emitting modern vehicle, including analytics of PAH and attempts of soot loading in road application.The modern MPI vehicles can emit a considerable amount of PN, which in some cases attains the level of Diesel exhaust gas without DPF and can pass over the actual European limit value for GDI (6.0 × 1011 #/km). The GPF-technology offers in this respect further potentials to reduce the PN-emissions of traffic. With GPF, in the investigated steady state operation, there is no significant visible nuclei mode and the ultrafine particles concentrations below 10 nm size are insignificant.

High air pollution in vehicle cabins due to traffic nanoparticle emission exposure and a solution for in-use vehicles

Vehicles operating in dense traffic take their cabin air from the low diluted exhaust gas cloud produced by other cars or trucks running ahead of them. They usually take it at a low level where the particle concentration and the concentration of heavy gases like NO2 are still high. Cabin air is thus collecting and storing emission peaks and air pollution in car cabins can therefore be extremely high - often ten times higher than even at roadside. Drivers commuting in big cities, taxi drivers, truckers and school buses might be exposed to this high pollution for several hours per working day, a group put at very high health risk.Cabin air of today’s vehicles usually passes a filter, but these filters are designed for visible road dust and pollen and according to the existing standards filtration of particles < 1 μm is very low. Lung penetration however, only starts < 0.5 μm. In the long run this could be changed by installing different filter systems, but what about the existing fleet? A filter system has been developed to reduce the concentration of ambient ultrafine particles in vehicle cabin air of in-use vehicles to very low levels, which is presented here.

Associations of Long-Term Exposure to Ultrafine Particles and Nitrogen Dioxide With Increased Incidence of Congestive Heart Failure and Acute Myocardial Infarction.

Although long-term exposure to traffic-related air pollutants such as nitrogen dioxide has been linked to cardiovascular disease (CVD) mortality, little is known about the association between ultrafine particles (UFPs), defined as particles less than or equal to 0.1 μm in diameter, and incidence of major CVD events. We conducted a population-based cohort study to assess the associations of chronic exposure to UFPs and nitrogen dioxide with incident congestive heart failure (CHF) and acute myocardial infarction. Our study population comprised all long-term Canadian residents aged 30-100 years who lived in Toronto, Ontario, Canada, during the years 1996-2012. We estimated annual concentrations of UFPs and nitrogen dioxide by means of land-use regression models and assigned these estimates to participants' postal-code addresses in each year during the follow-up period. We estimated hazard ratios for the associations of UFPs and nitrogen dioxide with incident CVD using random-effects Cox proportional hazards models. We controlled for smoking and obesity using an indirect adjustment method. Our cohorts comprised approximately 1.1 million individuals at baseline. In single-pollutant models, each interquartile-range increase in UFP exposure was associated with increased incidence of CHF (hazard ratio for an interquartile-range increase (HRIQR) = 1.03, 95% confidence interval (CI): 1.02, 1.05) and acute myocardial infarction (HRIQR = 1.05, 95% CI: 1.02, 1.07). Adjustment for fine particles and nitrogen dioxide did not materially change these estimated associations. Exposure to nitrogen dioxide was also independently associated with higher CHF incidence (HRIQR = 1.04, 95% CI: 1.03, 1.06).

Ultrafine Particles Measurement in Printing Industry Across West Malaysia

Ultrafine particles (UFPs) emission generated from devices such as printer and photocopy machines are known as potential risks to human health. However, limited information is available to study UFPs exposure generate from larger printer. Thus, this study aimed to determine the concentration of UFPs such as particle number (PN) and lung deposited surface area (LDSA) and investigates the influence of physical environment factors on UFPs in two types of offset lithographic printing rooms such as monochrome and color, across West Malaysia. The measurements of PN and LDSA were taken by using a condensation particle counter and the diffusion charger dosimeter during the printing activities. The mean values for PN and LDSA are 22215 particles/cm3 and 43 µm2/cm3, respectively. The exposure of UFPs from the monochrome room was found to be significantly higher than the color room (p &lt; 0.001 for PN; p &lt; 0.001 for LDSA) due to variation in the ventilation system. Based on correlation analysis, the physical environment factors, such as relative humidity, temperature, and air movement, were observed to influence the UFPs concentrations in printing room. The findings imply that a good selection of the ventilation system is important to minimize worker’s exposure to UFPs emission.

Characteristics of tire wear particles generated in a laboratory simulation of tire/road contact conditions

An experimental study of the non-exhaust emission characteristics of tire wear particulate matter (PM) was performed using a tire wear simulator. Building upon previous studies of PM emissions from non-exhaust sources, the total amount of tire wear particles (TWPs) was measured and their morphological and elemental characteristics were investigated. The peak size of TWPs generated at a constant speed of 80 km/h was around 2 µm. Under harsh friction conditions, the mean diameter increased and the size distribution broadened. In addition, the number concentration of ultrafine particles increased significantly. Based on morphological study, we divided TWPs into five categories: sausage-like particles, micron-sized spherical particles, torn debris, ultrafine particles, and aggregates of ultrafine particles. The results of energy dispersive spectroscopy analysis showed that ultrafine particles from tire tread were composed of carbon, silica, and sulfur.

Rotational and translation-free polishing of granite: surface quality and dust particles emission and dispersion

Reducing workers’ exposure to crystalline silica dust is currently a major challenge for granite manufacturing industries. In North America, occupational health regulations are becoming increasingly severe and demanding with respect to quartz dust particle exposure among workers. Of all granite transformation processes, dust control during polishing is the most difficult to realize. During the process, the rotary motion of the tool influences the dust particles, making it harder to capture them. This paper aims to investigate the surface quality, as well as fine particles (FP) and ultrafine particles (UFP) emission and dispersion during dry, rotational and translation-free granite polishing. This research was intended to gather data that could be used to validate dust dispersion simulation results when polishing granite. It was found that workers remain exposed to high concentrations of FP and UFP during this polishing process. In addition, dust particles were found to uniformly contaminate the workspace.

Composition of Metallic Elements and Size Distribution of Fine and Ultrafine Particles in a Steelmaking Factory.

Background: The characteristics of aerosol, in particular particle size and chemical composition, can have an impact on human health. Particle size distribution and chemical composition is a necessary parameter in occupational exposure assessment conducted in order to understand possible health effects. The aim of this study was to characterize workplace airborne particulate matter in a metallurgical setting by synergistically using two different approaches; Methodology: Analysis of inhalable fraction concentrations through traditional sampling equipment and ultrafine particles (UFP) concentrations and size distribution was conducted by an Electric Low-Pressure Impactor (ELPI+™). The determination of metallic elements (ME) in particles was carried out by inductively coupled plasma mass spectrometry; Results: Inhalable fraction and ME concentrations were below the limits set by Italian legislation and the American Conference of Governmental Industrial Hygienists (ACGIH, 2017). The median of UFP was between 4.00 × 104 and 2.92 × 105 particles/cm3. ME concentrations determined in the particles collected by ELPI show differences in size range distribution; Conclusions: The adopted synergistic approach enabled a qualitative and quantitative assessment of the particles in steelmaking factories. The results could lead to a better knowledge of occupational exposure characterization, in turn affording a better understanding of occupational health issues due to metal fumes exposure.

Study on combustion characteristics and particulate emissions of a common-rail diesel engine fueled with n-butanol and waste cooking oil blends

Biodiesel is a promising alternative fuel because of its renewability and extensive source of raw materials. Butanol can be blended in biodiesel to reduce the kinematic viscosity and promote the fuel atomization. In this respect, biodiesel was blended with 10% and 20% n-butanol, and the combustion characteristics and particulate emissions of the fuel blends were tested in a turbocharged, 6-cylinder, common rail diesel engine at a constant speed of 1400 rpm under seven engine loads. The experimental results show that under various engine loads, all of the butanol and biodiesel fuel blends provide faster combustion than diesel due to the higher oxygen content of n-butanol and the lower cetane number of butanol which results in stronger premixed combustion. The addition of butanol is beneficial to concentrating the heat release and thus shorten the combustion duration. With an increased proportion of butanol, soot emissions of butanol and biodiesel fuel blends decrease, the number concentration and volume concentration of ultrafine particles (UFPs) reduce noticeably. Meanwhile, the geometric mean diameters of UFPs decrease with an increase in butanol. With an increase of the engine loads, the number concentration peaks of UFPs gradually transfer from the size range of nucleation mode particles (NMPs) to the size range of accumulation mode particles (AMPs) due to the elevated combustion temperatures and high equivalence ratios. Moreover, biodiesel and fuel blends exhibit a higher percentage of NMPs as compared to diesel because of the fuel-bound oxygen, zero aromatics, and low sulfides.

Reduced Ultrafine Particle Concentration in Urban Air: Changes in Nucleation and Anthropogenic Emissions.

Nucleation is an important source of ambient ultrafine particles (UFP). We present observational evidence of the changes in the frequency and intensity of nucleation events in urban air by analyzing long-term particle size distribution measurements at an urban background site in Pittsburgh, Pennsylvania during 2001-2002 and 2016-2017. We find that both frequency and intensity of nucleation events have been reduced by 40-50% over the past 15 years, resulting in a 70% reduction in UFP concentrations from nucleation. On average, the particle growth rates are 30% slower than 15 years ago. We attribute these changes to dramatic reductions in SO2 (more than 90%) and other pollutant concentrations. Overall, UFP concentrations in Pittsburgh have been reduced by ∼48% in the past 15 years, with a ∼70% reduction in nucleation, ∼27% in weekday local sources (e.g., weekday traffic), and 49% in the regional background. Our results highlight that a reduction in anthropogenic emissions can considerably reduce nucleation events and UFP concentrations in a polluted urban environment.

Combining Measurements from Mobile Monitoring and a Reference Site To Develop Models of Ambient Ultrafine Particle Number Concentration at Residences.

Significant spatial and temporal variation in ultrafine particle (UFP; <100 nm in diameter) concentrations creates challenges in developing predictive models for epidemiological investigations. We compared the performance of land-use regression models built by combining mobile and stationary measurements (hybrid model) with a regression model built using mobile measurements only (mobile model) in Chelsea and Boston, MA (USA). In each study area, particle number concentration (PNC; a proxy for UFP) was measured at a stationary reference site and with a mobile laboratory driven along a fixed route during an ∼1-year monitoring period. In comparing PNC measured at 20 residences and PNC estimates from hybrid and mobile models, the hybrid model showed higher Pearson correlations of natural log-transformed PNC ( r = 0.73 vs 0.51 in Chelsea; r = 0.74 vs 0.47 in Boston) and lower root-mean-square error in Chelsea (0.61 vs 0.72) but no benefit in Boston (0.72 vs 0.71). All models overpredicted log-transformed PNC by 3-6% at residences, yet the hybrid model reduced the standard deviation of the residuals by 15% in Chelsea and 31% in Boston with better tracking of overnight decreases in PNC. Overall, the hybrid model considerably outperformed the mobile model and could offer reduced exposure error for UFP epidemiology.

An instantaneous spatiotemporal model for predicting traffic-related ultrafine particle concentration through mobile noise measurements

People living near roadways are exposed to high concentrations of ultrafine particles (UFP, diameter < 100 nm). This can result in adverse health effects such as respiratory illness and cardiovascular diseases. However, accurately characterizing the UFP number concentration requires expensive sets of instruments. The development of an UFP surrogate with cheap and convenient measures is needed. In this study, we used a mobile measurement platform with a Fast Mobility Particle Sizer (FMPS) and sound level meter to investigate the spatiotemporal relations of noise and UFP and identify the hotspots of UFP. UFP concentration levels were significantly influenced by temporal and spatial variations (p < 0.001). We proposed a Generalized Additive Models to predict UFP number concentration in the study area. The model uses noise and meteorological covariates to predict the UFP number concentrations at an industrial site in Taichung, Taiwan. During the one year sampling campaign from fall 2013 to summer 2014, mobile measurements were performed at least one week for each season, both on weekdays and weekends. The proposed model can explain 80% of deviance and has coefficient of determination (R2) of 0.77. Moreover, the developed UFP model was able to adequately predict UFP concentrations, and can provide people with a convenient way to determine UFP levels. Finally, the results from this study could help facilitate the future development of noise mobile measurement.

Exposure to Ambient Ultrafine Particles and Nitrogen Dioxide and Incident Hypertension and Diabetes.

Previous studies reported that long-term exposure to traffic-related air pollution may increase the incidence of hypertension and diabetes. However, little is known about the associations of ultrafine particles (≤0.1 μm in diameter) with these two conditions. We conducted a population-based cohort study to investigate the associations between exposures to ultrafine particles and nitrogen dioxide (NO2) and the incidence of diabetes and hypertension. Our study population included all Canadian-born residents aged 30 to 100 years who lived in the City of Toronto, Canada, from 1996 to 2012. Outcomes were ascertained using validated province-wide databases. We estimated annual concentrations of ultrafine particles and NO2 using land-use regression models and assigned these estimates to participants' annual postal code addresses during the follow-up period. Using random-effects Cox proportional hazards models, we calculated hazard ratios (HRs) and 95% confidence intervals (CIs) for ultrafine particles and NO2, adjusted for individual- and neighborhood-level covariates. We considered both single- and multipollutant models. Each interquartile change in exposure to ultrafine particles was associated with increased risk of incident hypertension (HR = 1.03; 95% CI = 1.02, 1.04) and diabetes (HR = 1.06; 95% CI = 1.05, 1.08) after adjusting for all covariates. These results remained unaltered with further control for fine particulate matter (≤2.5 μm; PM2.5) and NO2. Similarly, NO2 was positively associated with incident diabetes (HR = 1.06; 95% CI = 1.05, 1.07) after controlling for ultrafine particles and PM2.5. Exposure to traffic-related air pollution including ultrafine particles and NO2 may increase the risk for incident hypertension and diabetes. See video abstract at, http://links.lww.com/EDE/B337.

Comparison of Mutagenic Activities of Various Ultra-Fine Particles

Air pollution is increasing, along with consumption of fossil fuels such as coal and diesel gas. Air pollutants are known to be a major cause of respiratory-related illness and death, however, there are few reports on the genotoxic characterization of diverse air pollutants in Korea. In this study, we investigated the mutagenic activity of various particles such as diesel exhaust particles (DEP), combustion of rice straw (RSC), pine stem (PSC), and coal (CC), tunnel dust (TD), and road side dust (RD). Ultra-fine particles (UFPs) were collected by the glass fiber filter pad. Then, we performed a chemical analysis to see each of the component features of each particulate matter. The mutagenicity of various UFPs was determined by the Ames test with four Salmonella typhimurium strains with or without metabolic activation. The optimal concentrations of UFPs were selected based on result of a concentration decision test. Moreover, in order to compare relative mutagenicity among UFPs, we selected and tested DEP as mutation reference. DEP, RSC, and PSC induced concentration-dependent increases in revertant colony numbers with TA98, TA100, and TA1537 strains in the absence and presence of metabolic activation. DEP showed the highest specific activity among the particulate matters. In this study, we conclude that DEP, RSC, PSC, and TD displayed varying degrees of mutagenicity, and these results suggest that the mutagenicity of these air pollutants is associated with the presence of polycyclic aromatic hydrocarbons (PAHs) in these particulate matters.

Cyclist exposure to black carbon, ultrafine particles and heavy metals: An experimental study along two commuting routes near Antwerp, Belgium

Urban environments typically exhibit large atmospheric pollution variation, in both space and time. In contrast to traditional monitoring networks suffering from a limited spatial coverage, mobile platforms enable personalized high-resolution monitoring, providing valuable insights into personal atmospheric pollution exposure, and the identification of potential pollution hotspots. This study evaluated personal cyclist exposure to UFPs, BC and heavy metals whilst commuting near Antwerp, Belgium, by performing mobile measurements with wearable black carbon (BC) and ultrafine particle (UFP) instruments. Loaded micro-aethalometer filterstrips were chemically analysed and the inhaled pollutant dose determined from the exhibited heart rate. Considerable spatial pollutant variation was observed along the travelled routes, with distinct contributions from spatial factors (e.g. traffic intersections, urban park and market) and temporary events. On average 300% higher BC, 20% higher UFP and changing elemental concentrations are observed along the road traffic route (RT), when compared to the bicycle highway route (BH). Although the overall background pollution determines a large portion of the experienced personal exposure (in this case 53% for BC and 40% for UFP), cyclists can influence their personal atmospheric pollution exposure, by selecting less exposed commuting routes. Our results, hereby, strengthen the body of evidence in favour of further policy investments in isolated bicycle infrastructure.

Number concentrations of ultrafine particles and the incidence of postmenopausal breast cancer

Background: There have been a number of reports regarding possible associations between the incidence of female breast cancer and ambient air pollution. Only one study has been published about possible association with ultrafine particles (UFPs; &lt;0.1 μm). Methods: We conducted a case–control study of incident postmenopausal breast cancer in Montreal, Canada. Cases were identified between 1996 and 1997 from all hospitals that treated breast cancer. Controls were women diagnosed with other sites of cancer and frequency-matched to cases by hospital and 5-year age groups. Concentrations of UFPs were estimated using a land-use regression model developed in 2011–2012 and assigned to women’s residential addresses at time of diagnosis. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated using logistic regression models adjusting for individual-level and ecological covariates. Results: We found that the response functions between UFPs and incident, postmenopausal breast cancer were consistent with linearity. Adjusted ORs of 1.08 (95% CI = 0.96, 1.21) were found for an increase in UFPs equal to the interquartile range (IQR). We found higher ORs among cases with positive estrogen (ER+) and negative progesterone receptor (PR−) (OR = 1.23; 95% CI = 1.04–1.45) and for women with ER−/PR− status (OR = 1.23; 95% CI = 0.99–1.54). We also found stronger associations when analyses were restricted to those women who had not lived at their current address for 10 years or more (OR = 1.27; 95% CI = 0.94–1.71). Conclusions: Our findings suggest that exposure to ambient UFPs may increase the risk of incident postmenopausal breast cancer, especially among cases with ER+/PR− and ER−/PR− receptor status.