Three measures of forest fire smoke exposure and their associations with respiratory and cardiovascular health outcomes in a population-based cohort

Background: During the summer of 2003 numerous fires burned in British Columbia, Canada.Objectives: We examined the associations between respiratory and cardiovascular physician visits and hospital admissions, and three measures of smoke exposure over a 92-day study period (1 July to 30 September 2003).Methods: A population-based cohort of 281,711 residents was identified from administrative data. Spatially specific daily exposure estimates were assigned to each subject based on total measurements of particulate matter (PM) ≤ 10 μm in aerodynamic diameter (PM₁₀) from six regulatory tapered element oscillating microbalance (TEOM) air quality monitors, smoke-related PM₁₀ from a CALPUFF dispersion model run for the study, and a SMOKE exposure metric for plumes visible in satellite images. Logistic regression with repeated measures was used to estimate associations with each outcome.Results: The mean (± SD) exposure based on TEOM-measured PM₁₀ was 29 ± 31 μg/m³, with an interquartile range of 14–31 μg/m³. Correlations between the TEOM, smoke, and CALPUFF metrics were moderate (0.37–0.76). Odds ratios (ORs) for a 30-μg/m³ increase in TEOM-based PM₁₀ were 1.05 [95% confidence interval (CI), 1.03–1.06] for all respiratory physician visits, 1.16 (95% CI, 1.09–1.23) for asthma-specific visits, and 1.15 (95% CI, 1.00–1.29) for respiratory hospital admissions. Associations with cardiovascular outcomes were largely null.Conclusions: Overall we found that increases in TEOM-measured PM₁₀ were associated with increased odds of respiratory physician visits and hospital admissions, but not with cardiovascular health outcomes. Results indicating effects of fire smoke on respiratory outcomes are consistent with previous studies, as are the null results for cardiovascular outcomes. Some agreement between TEOM and the other metrics suggests that exposure assessment tools that are independent of air quality monitoring may be useful with further refinement.     

Emergency Admissions for Cardiovascular and Respiratory Diseases and the Chemical Composition of Fine Particle Air Pollution

Background

Population-based studies have estimated health risks of short-term exposure to fine particles using mass of PM_2.5 (particulate matter ≤ 2.5 μm in aerodynamic diameter) as the indicator. Evidence regarding the toxicity of the chemical components of the PM_2.5 mixture is limited.

Objective

In this study we investigated the association between hospital admission for cardiovascular disease (CVD) and respiratory disease and the chemical components of PM_2.5 in the United States.

Methods

We used a national database comprising daily data for 2000–2006 on emergency hospital admissions for cardiovascular and respiratory outcomes, ambient levels of major PM_2.5 chemical components [sulfate, nitrate, silicon, elemental carbon (EC), organic carbon matter (OCM), and sodium and ammonium ions], and weather. Using Bayesian hierarchical statistical models, we estimated the associations between daily levels of PM_2.5 components and risk of hospital admissions in 119 U.S. urban communities for 12 million Medicare enrollees (≥ 65 years of age).

Results

In multiple-pollutant models that adjust for the levels of other pollutants, an interquartile range (IQR) increase in EC was associated with a 0.80% [95% posterior interval (PI), 0.34–1.27%] increase in risk of same-day cardiovascular admissions, and an IQR increase in OCM was associated with a 1.01% (95% PI, 0.04–1.98%) increase in risk of respiratory admissions on the same day. Other components were not associated with cardiovascular or respiratory hospital admissions in multiple-pollutant models.

Conclusions

Ambient levels of EC and OCM, which are generated primarily from vehicle emissions, diesel, and wood burning, were associated with the largest risks of emergency hospitalization across the major chemical constituents of PM_2.5.     

Saharan dust and associations between particulate matter and daily mortality in Rome, Italy

Background: Outbreaks of Saharan-Sahel dust over Euro-Mediterranean areas frequently induce exceedances of the Europen Union''s 24-hr standard of 50 μg/m³ for particulate matter (PM) with aerodynamic diameter ≤ than 10 μm (PM₁₀).Objectives: We evaluated the effect of Saharan dust on the association between different PM fractions and daily mortality in Rome, Italy.Methods: In a study of 80,423 adult residents who died in Rome between 2001 and 2004, we performed a time-series analysis to explore the effects of PM_2.5, PM_2.5–10, and PM₁₀ on natural, cardiac, cerebrovascular, and respiratory mortality. We defined Saharan dust days by combining light detection and ranging (LIDAR) observations and analyses from operational models. We tested a Saharan dust–PM interaction term to evaluate the hypothesis that the effects of PM, especially coarse PM (PM_2.5–10), on mortality would be enhanced on dust days.Results: Interquartile range increases in PM_2.5–10 (10.8 μg/m³) and PM₁₀ (19.8 μg/m³) were associated with increased mortality due to natural, cardiac, cerebrovascular, and respiratory causes, with estimated effects ranging from 2.64% to 12.65% [95% confidence interval (CI), 1.18–25.42%] for the association between PM_2.5–10 and respiratory mortality (0- to 5-day lag). Associations of PM_2.5–10 with cardiac mortality were stronger on Saharan dust days (9.73%; 95% CI, 4.25–15.49%) than on dust-free days (0.86%; 95% CI, –2.47% to 4.31%; p = 0.005). Saharan dust days also modified associations between PM₁₀ and cardiac mortality (9.55% increase; 95% CI, 3.81–15.61%; vs. dust-free days: 2.09%; 95% CI, –0.76% to 5.02%; p = 0.02).Conclusions: We found evidence of effects of PM_2.5–10 and PM₁₀ on natural and cause-specific mortality, with stronger estimated effects on cardiac mortality during Saharan dust outbreaks. Toxicological and biological effects of particles from desert sources need to be further investigated and taken into account in air quality standards.     

Distributed lag analyses of daily hospital admissions and source-apportioned fine particle air pollution

Background

Past time-series studies of the health effects of fine particulate matter [aerodynamic diameter ≤ 2.5 μm (PM_2.5)] have used chemically nonspecific PM_2.5 mass. However, PM_2.5 is known to vary in chemical composition with source, and health impacts may vary accordingly.

Objective

We tested the association between source-specific daily PM_2.5 mass and hospital admissions in a time-series investigation that considered both single-lag and distributed-lag models.

Methods

Daily PM_2.5 speciation measurements collected in midtown Manhattan were analyzed via positive matrix factorization source apportionment. Daily and distributed-lag generalized linear models of Medicare respiratory and cardiovascular hospital admissions during 2001–2002 considered PM_2.5 mass and PM_2.5 from five sources: transported sulfate, residual oil, traffic, steel metal works, and soil.

Results

Source-related PM_2.5 (specifically steel and traffic) was significantly associated with hospital admissions but not with total PM_2.5 mass. Steel metal works–related PM_2.5 was associated with respiratory admissions for multiple-lag days, especially during the cleanup efforts at the World Trade Center. Traffic-related PM_2.5 was consistently associated with same-day cardiovascular admissions across disease-specific subcategories. PM_2.5 constituents associated with each source (e.g., elemental carbon with traffic) were likewise associated with admissions in a consistent manner. Mean effects of distributed-lag models were significantly greater than were maximum single-day effect models for both steel- and traffic-related PM_2.5.

Conclusions

Past analyses that have considered only PM_2.5 mass or only maximum single-day lag effects have likely underestimated PM_2.5 health effects by not considering source-specific and distributed-lag effects. Differing lag structures and disease specificity observed for steel-related versus traffic-related PM_2.5 raise the possibility of distinct mechanistic pathways of health effects for particles of differing chemical composition.     

Estimated short-term effects of coarse particles on daily mortality in Stockholm, Sweden

Background: Although serious health effects associated with particulate matter (PM) with aerodynamic diameter ≤ 10 μm (PM₁₀) and ≤ 2.5 μm (PM_2.5; fine fraction) are documented in many studies, the effects of coarse PM (PM_2.5–10) are still under debate.Objective: In this study, we estimated the effects of short-term exposure of PM_2.5–10 on daily mortality in Stockholm, Sweden.Method: We collected data on daily mortality for the years 2000 through 2008. Concentrations of PM₁₀, PM_2.5, ozone, and carbon monoxide were measured simultaneously in central Stockholm. We used additive Poisson regression models to examine the association between daily mortality and PM_2.5–10 on the day of death and the day before. Effect estimates were adjusted for other pollutants (two-pollutant models) during different seasons.Results: We estimated a 1.68% increase [95% confidence interval (CI): 0.20%, 3.15%] in daily mortality per 10-μg/m³ increase in PM_2.5–10 (single-pollutant model). The association with PM_2.5–10 was stronger for November through May, when road dust is most important (1.69% increase; 95% CI: 0.21%, 3.17%), compared with the rest of the year (1.31% increase; 95% CI: –2.08%, 4.70%), although the difference was not statistically significant. When adjusted for other pollutants, particularly PM_2.5, the effect estimates per 10 μg/m³ for PM_2.5–10 decreased slightly but were still higher than corresponding effect estimates for PM_2.5.Conclusions: Our analysis shows an increase in daily mortality associated with elevated urban background levels of PM_2.5–10. Regulation of PM_2.5–10 should be considered, along with actions to specifically reduce PM_2.5–10 emissions, especially road dust suspension, in cities.     

Acute effects of fine particulate air pollution on cardiac arrhythmia: the APACR study

Background: The mechanisms underlying the relationship between particulate matter (PM) air pollution and cardiac disease are not fully understood.Objectives: We examined the effects and time course of exposure to fine PM [aerodynamic diameter ≤ 2.5 μm (PM_2.5)] on cardiac arrhythmia in 105 middle-age community-dwelling healthy nonsmokers in central Pennsylvania.Methods: The 24-hr beat-to-beat electrocardiography data were obtained using a high-resolution Holter system. After visually identifying and removing artifacts, we summarized the total number of premature ventricular contractions (PVCs) and premature atrial contractions (PACs) for each 30-min segment. A personal PM_2.5 nephelometer was used to measure individual-level real-time PM_2.5 exposures for 24 hr. We averaged these data to obtain 30-min average time–specific PM_2.5 exposures. Distributed lag models under the framework of negative binomial regression and generalized estimating equations were used to estimate the rate ratio between 10-μg/m³ increases in average PM_2.5 over 30-min intervals and ectopy counts.Results: The mean ± SD age of participants was 56 ± 8 years, with 40% male and 73% non-Hispanic white. The 30-min mean ± SD for PM_2.5 exposure was 13 ± 22 μg/m³, and PAC and PVC counts were 0.92 ± 4.94 and 1.22 ± 7.18. Increases of 10 μg/m³ in average PM_2.5 concentrations during the same 30 min or the previous 30 min were associated with 8% and 3% increases in average PVC counts, respectively. PM_2.5 was not significantly associated with PAC count.Conclusion: PM_2.5 exposure within approximately 60 min was associated with increased PVC counts in healthy individuals.     

Short-term Associations between Fine and Coarse Particulate Matter and Hospitalizations in Southern Europe: Results from the MED-PARTICLES Project

Background: Evidence on the short-term effects of fine and coarse particles on morbidity in Europe is scarce and inconsistent.Objectives: We aimed to estimate the association between daily concentrations of fine and coarse particles with hospitalizations for cardiovascular and respiratory conditions in eight Southern European cities, within the MED-PARTICLES project.Methods: City-specific Poisson models were fitted to estimate associations of daily concentrations of particulate matter with aerodynamic diameter ≤ 2.5 μm (PM_2.5), ≤ 10 μm (PM₁₀), and their difference (PM_2.5–10) with daily counts of emergency hospitalizations for cardiovascular and respiratory diseases. We derived pooled estimates from random-effects meta-analysis and evaluated the robustness of results to co-pollutant exposure adjustment and model specification. Pooled concentration–response curves were estimated using a meta-smoothing approach.Results: We found significant associations between all PM fractions and cardiovascular admissions. Increases of 10 μg/m³ in PM_2.5, 6.3 μg/m³ in PM_2.5–10, and 14.4 μg/m³ in PM₁₀ (lag 0–1 days) were associated with increases in cardiovascular admissions of 0.51% (95% CI: 0.12, 0.90%), 0.46% (95% CI: 0.10, 0.82%), and 0.53% (95% CI: 0.06, 1.00%), respectively. Stronger associations were estimated for respiratory hospitalizations, ranging from 1.15% (95% CI: 0.21, 2.11%) for PM₁₀ to 1.36% (95% CI: 0.23, 2.49) for PM_2.5 (lag 0–5 days).Conclusions: PM_2.5 and PM_2.5–10 were positively associated with cardiovascular and respiratory admissions in eight Mediterranean cities. Information on the short-term effects of different PM fractions on morbidity in Southern Europe will be useful to inform European policies on air quality standards.Citation: Stafoggia M, Samoli E, Alessandrini E, Cadum E, Ostro B, Berti G, Faustini A, Jacquemin B, Linares C, Pascal M, Randi G, Ranzi A, Stivanello E, Forastiere F, the MED-PARTICLES Study Group. 2013. Short-term associations between fine and coarse particulate matter and hospitalizations in Southern Europe: results from the MED-PARTICLES project. Environ Health Perspect 121:1026–1033; http://dx.doi.org/10.1289/ehp.1206151     

Associations between Fine and Coarse Particles and Mortality in Mediterranean Cities: Results from the MED-PARTICLES Project

Background: Few studies have investigated the independent health effects of different size fractions of particulate matter (PM) in multiple locations, especially in Europe.Objectives: We estimated the short-term effects of PM with aerodynamic diameter ≤ 10 μm (PM₁₀), ≤ 2.5 μm (PM_2.5), and between 2.5 and 10 μm (PM_2.5–10) on all-cause, cardiovascular, and respiratory mortality in 10 European Mediterranean metropolitan areas within the MED-PARTICLES project.Methods: We analyzed data from each city using Poisson regression models, and combined city-specific estimates to derive overall effect estimates. We evaluated the sensitivity of our estimates to co-pollutant exposures and city-specific model choice, and investigated effect modification by age, sex, and season. We applied distributed lag and threshold models to investigate temporal patterns of associations.Results: A 10-μg/m³ increase in PM_2.5 was associated with a 0.55% (95% CI: 0.27, 0.84%) increase in all-cause mortality (0–1 day cumulative lag), and a 1.91% increase (95% CI: 0.71, 3.12%) in respiratory mortality (0–5 day lag). In general, associations were stronger for cardiovascular and respiratory mortality than all-cause mortality, during warm versus cold months, and among those ≥ 75 versus < 75 years of age. Associations with PM_2.5–10 were positive but not statistically significant in most analyses, whereas associations with PM₁₀ seemed to be driven by PM_2.5.Conclusions: We found evidence of adverse effects of PM_2.5 on mortality outcomes in the European Mediterranean region. Associations with PM_2.5–10 were positive but smaller in magnitude. Associations were stronger for respiratory mortality when cumulative exposures were lagged over 0–5 days, and were modified by season and age.     

Risk of nonaccidental and cardiovascular mortality in relation to long-term exposure to low concentrations of fine particulate matter: a Canadian national-level cohort study

Background: Few cohort studies have evaluated the risk of mortality associated with long-term exposure to fine particulate matter [≤ 2.5 μm in aerodynamic diameter (PM_2.5)]. This is the first national-level cohort study to investigate these risks in Canada.Objective: We investigated the association between long-term exposure to ambient PM_2.5 and cardiovascular mortality in nonimmigrant Canadian adults.Methods: We assigned estimates of exposure to ambient PM_2.5 derived from satellite observations to a cohort of 2.1 million Canadian adults who in 1991 were among the 20% of the population mandated to provide detailed census data. We identified deaths occurring between 1991 and 2001 through record linkage. We calculated hazard ratios (HRs) and 95% confidence intervals (CIs) adjusted for available individual-level and contextual covariates using both standard Cox proportional survival models and nested, spatial random-effects survival models.Results: Using standard Cox models, we calculated HRs of 1.15 (95% CI: 1.13, 1.16) from nonaccidental causes and 1.31 (95% CI: 1.27, 1.35) from ischemic heart disease for each 10-μg/m³ increase in concentrations of PM_2.5. Using spatial random-effects models controlling for the same variables, we calculated HRs of 1.10 (95% CI: 1.05, 1.15) and 1.30 (95% CI: 1.18, 1.43), respectively. We found similar associations between nonaccidental mortality and PM_2.5 based on satellite-derived estimates and ground-based measurements in a subanalysis of subjects in 11 cities.Conclusions: In this large national cohort of nonimmigrant Canadians, mortality was associated with long-term exposure to PM_2.5. Associations were observed with exposures to PM_2.5 at concentrations that were predominantly lower (mean, 8.7 μg/m³; interquartile range, 6.2 μg/m³) than those reported previously.     

Black carbon as an additional indicator of the adverse health effects of airborne particles compared with PM10 and PM2.5

Background: Current air quality standards for particulate matter (PM) use the PM mass concentration [PM with aerodynamic diameters ≤ 10 μm (PM₁₀) or ≤ 2.5 μm (PM_2.5)] as a metric. It has been suggested that particles from combustion sources are more relevant to human health than are particles from other sources, but the impact of policies directed at reducing PM from combustion processes is usually relatively small when effects are estimated for a reduction in the total mass concentration.Objectives: We evaluated the value of black carbon particles (BCP) as an additional indicator in air quality management.Methods: We performed a systematic review and meta-analysis of health effects of BCP compared with PM mass based on data from time-series studies and cohort studies that measured both exposures. We compared the potential health benefits of a hypothetical traffic abatement measure, using near-roadway concentration increments of BCP and PM_2.5 based on data from prior studies.Results: Estimated health effects of a 1-μg/m³ increase in exposure were greater for BCP than for PM₁₀ or PM_2.5, but estimated effects of an interquartile range increase were similar. Two-pollutant models in time-series studies suggested that the effect of BCP was more robust than the effect of PM mass. The estimated increase in life expectancy associated with a hypothetical traffic abatement measure was four to nine times higher when expressed in BCP compared with an equivalent change in PM_2.5 mass.Conclusion: BCP is a valuable additional air quality indicator to evaluate the health risks of air quality dominated by primary combustion particles.     

Does Air Pollution Trigger Infant Mortality in Western Europe? A Case-Crossover Study

Background: Numerous studies show associations between fine particulate air pollutants [particulate matter with an aerodynamic diameter ≤ 10 μm (PM₁₀)] and mortality in adults.Objectives: We investigated short-term effects of elevated PM₁₀ levels on infant mortality in Flanders, Belgium, and studied whether the European Union (EU) limit value protects infants from the air pollution trigger.Methods: In a case-crossover analysis, we estimated the risk of dying from nontraumatic causes before 1 year of age in relation to outdoor PM₁₀ concentrations on the day of death. We matched control days on temperature to exclude confounding by variations in daily temperature.Results: During the study period (1998–2006), PM₁₀ concentration averaged 31.9 ± 13.8 μg/m³. In the entire study population (n = 2,382), the risk of death increased by 4% [95% confidence interval (CI), 0–8%; p = 0.045] for a 10-μg/m³ increase in daily mean PM₁₀. However, this association was significant only for late neonates (2–4 weeks of age; n = 372), in whom the risk of death increased by 11% (95% CI, 1–22%; p = 0.028) per 10-μg/m³ increase in PM₁₀. In this age class, infants were 1.74 (95% CI, 1.18–2.58; p = 0.006) times more likely to die on days with a mean PM₁₀ above the EU limit value of 50 μg/m³ than on days below this cutoff.Conclusions: Even in an affluent region in Western Europe, where infant mortality is low, days with higher PM air pollution are associated with an increased risk of infant mortality. Assuming causality, the current EU limit value for PM₁₀, which may be exceeded on 35 days/year, does not prevent PM₁₀ from triggering mortality in late neonates.     

Long-term urban particulate air pollution, traffic noise, and arterial blood pressure

Background: Recent studies have shown an association of short-term exposure to fine particulate matter (PM) with transient increases in blood pressure (BP), but it is unclear whether long-term exposure has an effect on arterial BP and hypertension.Objectives: We investigated the cross-sectional association of residential long-term PM exposure with arterial BP and hypertension, taking short-term variations of PM and long-term road traffic noise exposure into account.Methods: We used baseline data (2000–2003) on 4,291 participants, 45–75 years of age, from the Heinz Nixdorf Recall Study, a population-based prospective cohort in Germany. Urban background exposure to PM with aerodynamic diameter ≤ 2.5 μm (PM_2.5) and ≤ 10 μm (PM₁₀) was assessed with a dispersion and chemistry transport model. We used generalized additive models, adjusting for short-term PM, meteorology, traffic proximity, and individual risk factors.Results: An interquartile increase in PM_2.5 (2.4 μg/m³) was associated with estimated increases in mean systolic and diastolic BP of 1.4 mmHg [95% confidence interval (CI): 0.5, 2.3] and 0.9 mmHg (95% CI: 0.4, 1.4), respectively. The observed relationship was independent of long-term exposure to road traffic noise and robust to the inclusion of many potential confounders. Residential proximity to high traffic and traffic noise exposure showed a tendency toward higher BP and an elevated prevalence of hypertension.Conclusions: We found an association of long-term exposure to PM with increased arterial BP in a population-based sample. This finding supports our hypothesis that long-term PM exposure may promote atherosclerosis, with air-pollution–induced increases in BP being one possible biological pathway.     

Contrasts in oxidative potential and other particulate matter characteristics collected near major streets and background locations

Background: Measuring the oxidative potential of airborne particulate matter (PM) may provide a more health-based exposure measure by integrating various biologically relevant properties of PM into a single predictor of biological activity.Objectives: We aimed to assess the contrast in oxidative potential of PM collected at major urban streets and background locations, the associaton of oxidative potential with other PM characteristics, and the oxidative potential in different PM size fractions.Methods: Measurements of PM with aerodynamic diameter ≤ 10 μm (PM₁₀), PM with aerodynamic diameter ≤ 2.5 μm (PM_2.5), soot, elemental composition, and oxidative potential of PM were conducted simultaneously in samples from 8 major streets and 10 urban and suburban background locations in the Netherlands. Six 1-week measurements were performed at each location over a 6-month period in 2008. Oxidative potential was measured as the ability to generate hydroxyl radicals in the presence of hydrogen peroxide in all PM₁₀ samples and a subset of PM_2.5 samples.Results: The PM₁₀ oxidative potential of samples from major streets was 3.6 times higher than at urban background locations, exceeding the contrast for PM mass, soot, and all measured chemical PM characteristics. The contrast between major streets and suburban background locations was even higher (factor of 6.5). Oxidative potential was highly correlated with soot, barium, chromium, copper, iron, and manganese. Oxidative potential of PM₁₀ was 4.6 times higher than the oxidative potential of PM_2.5 when expressed per volume unit and 3.1 times higher when expressed per mass unit.Conclusions: The oxidative potential of PM near major urban roads was highly elevated compared with urban and suburban background locations, and the contrast was greater than that for any other measured PM characteristic.     

Air Pollution and Childhood Respiratory Allergies in the United States

Background

Childhood respiratory allergies, which contribute to missed school days and other activity limitations, have increased in recent years, possibly due to environmental factors.

Objective

In this study we examined whether air pollutants are associated with childhood respiratory allergies in the United States.

Methods

For the approximately 70,000 children from the 1999–2005 National Health Interview Survey eligible for this study, we assigned between 40,000 and 60,000 ambient pollution monitoring data from the U.S. Environmental Protection Agency, depending on the pollutant. We used monitors within 20 miles of the child’s residential block group. We used logistic regression models, fit with methods for complex surveys, to examine the associations between the reporting of respiratory allergy or hay fever and annual average exposure to particulate matter ≤ 2.5 μm in diameter (PM_2.5), PM ≤ 10 μm in diameter, sulfur dioxide, and nitrogen dioxide and summer exposure to ozone, controlling for demographic and geographic factors.

Results

Increased respiratory allergy/hay fever was associated with increased summer O₃ levels [adjusted odds ratio (AOR) per 10 ppb = 1.20; 95% confidence interval (CI), 1.15–1.26] and increased PM_2.5 (AOR per 10 μg/m³ = 1.23; 95% CI, 1.10–1.38). These associations persisted after stratification by urban–rural status, inclusion of multiple pollutants, and definition of exposures by differing exposure radii. No associations between the other pollutants and the reporting respiratory allergy/hay fever were apparent.

Conclusions

These results provide evidence of adverse health for children living in areas with chronic exposure to higher levels of O₃ and PM_2.5 compared with children with lower exposures.     

Ambient air pollution and birth weight in full-term infants in Atlanta, 1994-2004

Background

An emerging body of evidence suggests that ambient levels of air pollution during pregnancy are associated with fetal growth.

Objectives

We examined relationships between birth weight and temporal variation in ambient levels of carbon monoxide, nitrogen dioxide (NO₂), sulfur dioxide (SO₂), ozone, particulate matter ≤ 10 μm in diameter (PM₁₀), ≤ 2.5 μm (PM_2.5), 2.5 to 10 μm (PM_2.5–10), and PM_2.5 chemical component measurements for 406,627 full-term births occurring between 1994 and 2004 in five central counties of metropolitan Atlanta.

Methods

We assessed relationships between birth weight and pollutant concentrations during each infant’s first month of gestation and third trimester, as well as in each month of pregnancy using distributed lag models. We also conducted capture-area analyses limited to mothers residing within 4 miles (6.4 km) of each air quality monitoring station.

Results

In the five-county analysis, ambient levels of NO₂, SO₂, PM_2.5 elemental carbon, and PM_2.5 water-soluble metals during the third trimester were significantly associated with small reductions in birth weight (−4 to −16 g per interquartile range increase in pollutant concentrations). Third-trimester estimates were generally higher in Hispanic and non-Hispanic black infants relative to non-Hispanic white infants. Distributed lag models were also suggestive of associations between air pollutant concentrations in late pregnancy and reduced birth weight. The capture-area analyses provided little support for the associations observed in the five-county analysis.

Conclusions

Results provide some support for an effect of ambient air pollution in late pregnancy on birth weight in full-term infants.     

Survival analysis of long-term exposure to different sizes of airborne particulate matter and risk of infant mortality using a birth cohort in Seoul, Korea

Background

Several studies suggest that airborne particulate matter (PM) is associated with infant mortality; however, most focused on short-term exposure to larger particles.

Objectives

We evaluated associations between long-term exposure to different sizes of particles [total suspended particles (TSP), PM ≤ 10 μm in aerodynamic diameter (PM₁₀), ≤ 10–2.5 μm (PM_10–2.5), and ≤ 2.5 μm (PM_2.5)] and infant mortality in a cohort in Seoul, Korea, 2004–2007.

Methods

The study includes 359,459 births with 225 deaths. We applied extended Cox proportional hazards modeling with time-dependent covariates to three mortality categories: all causes, respiratory, and sudden infant death syndrome (SIDS). We calculated exposures from birth to death (or end of eligibility for outcome at 1 year of age) and pregnancy (gestation and each trimester) and treated exposures as time-dependent variables for subjects’ exposure for each pollutant. We adjusted by sex, gestational length, season of birth, maternal age and educational level, and heat index. Each cause of death and exposure time frame was analyzed separately.

Results

We found a relationship between gestational exposures to PM and infant mortality from all causes or respiratory causes for normal-birth-weight infants. For total mortality (all causes), risks were 1.44 (95% confidence interval, 1.06–1.97), 1.65 (1.18–2.31), 1.53 (1.22–1.90), and 1.19 (0.83–1.70) per interquartile range increase in TSP, PM₁₀, PM_2.5, and PM_10–2.5, respectively; for respiratory mortality, risks were 3.78 (1.18–12.13), 6.20 (1.50–25.66), 3.15 (1.26–7.85), and 2.86 (0.76–10.85). For SIDS, risks were 0.92 (0.33–2.58), 1.15 (0.38–3.48), 1.42 (0.71–2.87), and 0.57 (0.16–1.96), respectively.

Conclusions

Our findings provide supportive evidence of an association of long-term exposure to PM air pollution with infant mortality.     

Size-segregated particle number concentrations and respiratory emergency room visits in Beijing, China

Background

The link between concentrations of particulate matter (PM) and respiratory morbidity has been investigated in numerous studies.

Objectives

The aim of this study was to analyze the role of different particle size fractions with respect to respiratory health in Beijing, China.

Methods

Data on particle size distributions from 3 nm to 1 μm; PM₁₀ (PM ≤ 10 μm), nitrogen dioxide (NO₂), and sulfur dioxide concentrations; and meteorologic variables were collected daily from March 2004 to December 2006. Concurrently, daily counts of emergency room visits (ERV) for respiratory diseases were obtained from the Peking University Third Hospital. We estimated pollutant effects in single- and two-pollutant generalized additive models, controlling for meteorologic and other time-varying covariates. Time-delayed associations were estimated using polynomial distributed lag, cumulative effects, and single lag models.

Results

Associations of respiratory ERV with NO₂ concentrations and 100–1,000 nm particle number or surface area concentrations were of similar magnitude—that is, approximately 5% increase in respiratory ERV with an interquartile range increase in air pollution concentration. In general, particles < 50 nm were not positively associated with ERV, whereas particles 50–100 nm were adversely associated with respiratory ERV, both being fractions of ultrafine particles. Effect estimates from two-pollutant models were most consistent for NO₂.

Conclusions

Present levels of air pollution in Beijing were adversely associated with respiratory ERV. NO₂ concentrations seemed to be a better surrogate for evaluating overall respiratory health effects of ambient air pollution than PM₁₀ or particle number concentrations in Beijing.     

The effects of particulate matter sources on daily mortality: a case-crossover study of Barcelona, Spain

Background: Dozens of studies link acute exposure to particulate matter (PM) air pollution with premature mortality and morbidity, but questions remain about which species and sources in the vast PM mixture are responsible for the observed health effects. Although a few studies exist on the effects of species and sources in U.S. cities, European cities—which have a higher proportion of diesel engines and denser urban populations—have not been well characterized. Information on the effects of specific sources could aid in targeting pollution control and in articulating the biological mechanisms of PM.Objectives: Our study examined the effects of various PM sources on daily mortality for 2003 through 2007 in Barcelona, a densely populated city in the northeast corner of Spain.Methods: Source apportionment for PM ≤ 2.5 μm and ≤ 10 µm in aerodynamic diameter (PM_2.5 and PM₁₀) using positive matrix factorization identified eight different factors. Case-crossover regression analysis was used to estimate the effects of each factor.Results: Several sources of PM_2.5, including vehicle exhaust, fuel oil combustion, secondary nitrate/organics, minerals, secondary sulfate/organics, and road dust, had statistically significant associations (p < 0.05) with all-cause and cardiovascular mortality. Also, in some cases relative risks for a respective interquartile range increase in concentration were higher for specific sources than for total PM_2.5 mass.Conclusions: These results along with those from our multisource models suggest that traffic, sulfate from shipping and long-range transport, and construction dust are important contributors to the adverse health effects linked to PM.     

Fine particulate matter constituents and cardiopulmonary mortality in a heavily polluted Chinese city

Background: Although ambient fine particulate matter (PM_2.5; particulate matter ≤ 2.5 µm in aerodynamic diameter) has been linked to adverse human health effects, the chemical constituents that cause harm are unknown. To our knowledge, the health effects of PM_2.5 constituents have not been reported for a developing country.Objectives: We examined the short-term association between PM_2.5 constituents and daily mortality in Xi’an, a heavily polluted Chinese city.Methods: We obtained daily mortality data and daily concentrations of PM_2.5, organic carbon (OC), elemental carbon (EC), and 10 water-soluble ions for 1 January 2004 through 31 December 2008. We also measured concentrations of fifteen elements 1 January 2006 through 31 December 2008. We analyzed the data using over-dispersed generalized linear Poisson models.Results: During the study period, the mean daily average concentration of PM_2.5 in Xi’an was 182.2 µg/m³. Major contributors to PM_2.5 mass included OC, EC, sulfate, nitrate, and ammonium. After adjustment for PM_2.5 mass, we found significant positive associations of total, cardiovascular, or respiratory mortality with OC, EC, ammonium, nitrate, chlorine ion, chlorine, and nickel for at least 1 lag day. Nitrate demonstrated stronger associations with total and cardiovascular mortality than PM_2.5 mass. For a 1-day lag, interquartile range increases in PM_2.5 mass and nitrate (114.9 and 15.4 µg/m³, respectively) were associated with 1.8% [95% confidence interval (CI): 0.8%, 2.8%] and 3.8% (95% CI: 1.7%, 5.9%) increases in total mortality.Conclusions: Our findings suggest that PM_2.5 constituents from the combustion of fossil fuel may have an appreciable influence on the health effects attributable to PM_2.5 in Xi’an.     

Time-series analysis of mortality effects of fine particulate matter components in Detroit and Seattle

Background

Recent toxicological and epidemiological studies have shown associations between particulate matter (PM) and adverse health effects, but which PM components are most influential is less well known.

Objectives

In this study, we used time-series analyses to determine the associations between daily fine PM [PM ≤ 2.5 μm in aerodynamic diameter (PM_2.5)] concentrations and daily mortality in two U.S. cities—Seattle, Washington, and Detroit, Michigan.

Methods

We obtained daily PM_2.5 filters for the years of 2002–2004 and analyzed trace elements using X-ray fluorescence and black carbon using light reflectance as a surrogate measure of elemental carbon. We used Poisson regression and distributed lag models to estimate excess deaths for all causes and for cardiovascular and respiratory diseases adjusting for time-varying covariates. We computed the excess risks for interquartile range increases of each pollutant at lags of 0 through 3 days for both warm and cold seasons.

Results

The cardiovascular and respiratory mortality series exhibited different source and seasonal patterns in each city. The PM_2.5 components and gaseous pollutants associated with mortality in Detroit were most associated with warm season secondary aerosols and traffic markers. In Seattle, the component species most closely associated with mortality included those for cold season traffic and other combustion sources, such as residual oil and wood burning.

Conclusions

The effects of PM_2.5 on daily mortality vary with source, season, and locale, consistent with the hypothesis that PM composition has an appreciable influence on the health effects attributable to PM.