Does area level socioeconomic status modify the effects of PM10 on preterm delivery?

Background

Air pollution has been one of the focal points for investigations of maternal health and birth, and an association has been found between air pollution and birth outcomes. Some individual-level risk factors of mothers have been identified as strong predictors of preterm delivery (PTD). Recent literature has shown that the neighborhood environment of the mother and child has an independent influence on birth outcomes that was not explained by individual-level risk factors.

Objective

This study explored the effects of maternal exposure to particulate air pollution (PM₁₀) and its relationship to the probability of preterm delivery (PTD) in Seoul, Korea. Our hypothesis was that PM₁₀ increased the probability of PTD, and that the area level socioeconomic status (SES), measured by monthly average household income, modified the PM₁₀ effects on PTD after controlling for individual-level risk factors such as individual-level SES.

Data and Method

Birth data from the Korean National Statistics Office consisted of records on 433,173 singleton births in the years 2000-2003, and included individual characteristics. Area-level characteristics were also controlled for in 25 administrative regions in Seoul. Maternal exposure to PM₁₀ was calculated at an individual level for each trimester using information from monitoring sites in residential areas. Hourly data on PM₁₀ for 1999-2003 were acquired from the National Institute of Environment Research. Birth outcome was dichotomously coded: term birth (gestation ≥37 weeks) or PTD (gestation <37 weeks). For multilevel analysis, we conducted a hierarchical logistic regression with a random intercept for each administrative area to account for the hierarchical nature of the data.

Results

We found that area-level SES modified the PM₁₀ effects on PTD, specifically among those who were in low SES areas. Results of multilevel analyses showed that an increase in PM₁₀ by 10 μg/m³ led to a statistically significant increase in the probability of PTD [3.12% (95% CI, 0.17-6.15)] during the 2nd trimester in the low-income group. Analyses using the stratified population found a 3.4% increase (95% CI, 0.31-6.58) in the probability of PTD during the 2nd trimester in areas with low income.

Conclusion

Mothers exposed to higher PM₁₀ in Seoul, Korea, had a higher probability of PTD. Individual-level characteristics had different effects on the probability of PTD depending on the area-level SES. Area-level SES modified the effect of PM₁₀ concentration on PTD.     

Association between daily mortality from respiratory and cardiovascular diseases and air pollution in Taiwan

Background

Many studies have investigated the effects of air pollutants on disease and mortality. However, the results remain inconsistent and inconclusive. We thought that the impact of different seasons or ages of people may explain these differences.

Methods

Measurement of the five pollutants (particulate matter <10 μm in aerodynamic diameter (PM₁₀), SO₂, NO₂, O₃, and CO) was monitored by automated measuring units at five different stations. Monitoring stations were provided by the Taiwan Environmental Protection Agency (EPA) from 1997 to 1999. The subjects in the study were classified in two groups: those 65 years of age and older, and those of all ages (including the subjects in the ?65 group). Data on daily mortality caused by respiratory disease, cardiovascular disease, and all other causes including the two aforementioned was collected by the Taiwan Department of Health (DOH). A time-series regression model was used to analyze the relative risk of respiratory and cardiovascular diseases due to air pollution in the summer and winter seasons.

Results

Risk of death from all causes and mortality from cardiovascular diseases during winter was significantly positively correlated with levels of SO₂, CO, and NO₂ for both groups of subjects and additionally with PM₁₀ for the elderly (?65 years old) group. There were significant positive correlations with respiratory diseases and levels of O₃ for both groups. However, the only significant positive correlation was with O₃ (RR=1.283) for the elderly group during summer. No other parameters showed significance for either group.

Conclusion

Our findings contribute to the evidence of an association between SO₂, CO, NO₂, and PM₁₀ and mortality from respiratory and cardiovascular diseases, especially among elderly people during the winter season.     

PM10 Exposure and Non-accidental Mortality in Asian Populations: A Meta-analysis of Time-series and Case-crossover Studies

Objectives

We investigated the association between particulate matter less than 10 µm in aerodynamic diameter (PM₁₀) exposure and non-accidental mortality in Asian populations by meta-analysis, using both time-series and case-crossover analysis.

Methods

Among the 819 published studies searched from PubMed and EMBASE using key words related to PM₁₀ exposure and non-accidental mortality in Asian countries, 8 time-series and 4 case-crossover studies were selected for meta-analysis after exclusion by selection criteria. We obtained the relative risk (RR) and 95% confidence intervals (CI) of non-accidental mortality per 10 µg/m³ increase of daily PM₁₀ from each study. We used Q statistics to test the heterogeneity of the results among the different studies and evaluated for publication bias using Begg funnel plot and Egger test.

Results

Testing for heterogeneity showed significance (p<0.001); thus, we applied a random-effects model. RR (95% CI) per 10 µg/m³ increase of daily PM₁₀ for both the time-series and case-crossover studies combined, time-series studies relative risk only, and case-crossover studies only, were 1.0047 (1.0033 to 1.0062), 1.0057 (1.0029 to 1.0086), and 1.0027 (1.0010 to 1.0043), respectively. The non-significant Egger test suggested that this analysis was not likely to have a publication bias.

Conclusions

We found a significant positive association between PM₁₀ exposure and non-accidental mortality among Asian populations. Continued investigations are encouraged to contribute to the health impact assessment and public health management of air pollution in Asian countries.     

Air pollution exposure and self-reported cardiovascular disease

Background

Studies suggest that increases of fine particle concentrations (PM_2.5) could be linked with a rise in cardiovascular disease. With approximately 25% of American adults aged 30 and older reporting having either heart disease or hypertension it is possible that exposure to air pollution could have significant public health consequences. This study examined the relationship between PM_2.5 and the prevalence of self-reported hypertension and heart disease using data from a large nation-wide survey.

Study design

Adults, 30 years of age or older, who participated in the National Health Interview Survey (NHIS) from 1999 to 2005 were linked to annual PM_2.5 data from the US Environmental Protection Agency (N=132,224). Annual air quality estimates were averaged from monitors within 20 miles of the respondent's residential block group. Respondents who reported being told they had hypertension by a health professional on two or more separate occasions were defined as hypertensive. Heart disease was defined as answering, “yes” to one or more of three NHIS questions on heart disease.

Results

A 10 μg/m³ increase in PM_2.5 exposure was associated with a small elevated risk of hypertension (adjusted odds ratio (OR) 1.05, 95% confidence interval (CI) 1.00-1.10) risk of heart disease (1.08 95% CI 1.00-1.16). The association between PM_2.5 and hypertension was found in non-Hispanic white adults (OR 1.10 95% CI 1.04-1.17) but not in non-Hispanic black or Hispanic adults.

Conclusions

Findings from this study complement those from other studies and indicate that PM_2.5 adversely affects cardiovascular health. Our results are consistent with other studies in showing a small association between exposure to PM_2.5 and cardiovascular outcomes.     

Public perception and behavior change in relationship to hot weather and air pollution

Background

Changes in climate systems are increasing heat wave frequency and air stagnation, both conditions associated with exacerbating poor air quality and of considerable public health concern.

Objectives

Heat and air pollution advisory systems are in place in many cities for early detection and response to reduce health consequences, or severity of adverse conditions. Whereas the ability to forecast heat waves and/or air pollution episodes has become increasingly sophisticated and accurate, little is known about the effectiveness of advisories in altering public behavior.

Methods

Air quality and meteorological conditions were measured during advisory and control days in Portland, OR and Houston, TX in 2005 and 2006 and 1962 subjects were interviewed by telephone about their perception and response to these conditions.

Results

Elevated ambient temperatures were accurately recognized regardless of air conditioning use; in Portland, respondents resorted to active cooling behavior (AC, fan, etc.), while in Houston no such change was observed. More heat-related symptoms were reported in Portland compared to Houston, probably due to low air conditioning use in the northwest. One-third of study participants were aware of air quality advisories but only ∼10-15% claimed to have changed activities during such an episode. Not the advisory, however, drove their behavior change, but rather the perception of poor air quality, which was not related to PM_2.5 or ozone measurements.

Conclusions

Messages are not reaching the public during potentially hazardous weather and air quality conditions. Climatic forecasts are increasingly predictive but public agencies fail to mount an appropriate outreach response.     

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.     

A comparative study to evaluate the safety and immunogenicity of two lots of Haemophilus influenzae type-B conjugate vaccine manufactured at different scales

Objective

To compare the immunogenicity and safety of two different lots of SII Haemophilus influenzae type-B-tetanus toxoid conjugate (SII HibP_RO) vaccine manufactured at different scales when given in 3-dose schedule.

Design

Phase IV, open label, comparative, randomized parallel group study.

Setting

Shirdi Sai Baba Hospital, Vadu Budruk, Pune and Pediatrics Department of King Edward Memorial Hospital Research Centre, Pune.

Subjects

204 normal healthy infants of age 6-8 weeks at the time of first vaccination.

Methods

The eligible subjects received 3 doses of 0.5 ml of SII HibP_RO vaccine of either lot depending upon randomization number, intramuscularly in right thigh in the EPI schedule of 6, 10 and 14 weeks. They also received concomitantly DTP-HB vaccine intramuscularly on left thigh and Oral Polio vaccine (OPV). Solicited reactions were captured for 7 days following each vaccination; the events beyond 7 days till day 28 were captured as unsolicited adverse events. Serious Adverse Events (SAEs) were looked for throughout the subject participation. Blood samples were collected at baseline (before the first dose) and one month after the third dose for anti-PRP (polyribosylribitol phosphate) antibodies.

Results

In both groups, more than 98% subjects achieved short-term seroprotection (anti-PRP ≥ 0.15 μg/ml) after 3 doses. The long-term seroprotection (anti-PRP ≥ 1 μg/ml) was 87% and 80% in infants receiving lot manufactured at industrial scale and small scale respectively. Short and long term seroprotection and GMTs increased significantly as compared to baseline in both the groups. Overall local pain (52% and 58%), redness (30% and 41%), swelling (34% and 44%), fever (6% and 6%) and irritability (52% and 50%) were reported in infants receiving lot manufactured at industrial scale and small scale respectively. Majority of the reactions were mild and resoled without any sequelae. Four SAEs, none of them causally related to the study vaccine, occurred during study.

Conclusion

SII HibP_RO vaccines manufactured in small and industrial scale are equally immunogenic, safe and confer adequate seroprotection to infants of 6-14 weeks of age. Scaling up production process has not affected the safety and immune response in the target population.     

Influences of the weather and air pollutants on cardiovascular disease in the metropolitan area of São Paulo

Objective

Cardiovascular disease (CVD) has been associated with meteorological variables and pollutant levels. However, these relationships have rarely been studied in São Paulo, Brazil.

Methods

From 1996 to 2000, biometeorological indices including meteorological variables such as temperature, relative humidity, and wind were used to measure thermal comfort in elderly people mortality (>65 years old), and CVD was quantified.

Results

Statistical analysis showed a significant negative loading between CVD and meteorological variables as well as thermal comfort indices. The CVD curve was a U-shaped, showing higher value for cold stress than for heat stress. The results clearly show seasonal variations in CVD mortality rates, which were higher in winter. Meteorological variables were found to play an important role as well as through the thermal comfort indices. The air pollutants, PM₁₀ and SO₂, except ozone, presented positive loadings with CVD, albeit less than statistically significant.     

Social disadvantage, air pollution, and asthma physician visits in Toronto, Canada

Background

Previous research demonstrates that ambient air pollution exacerbates asthma. Asthma morbidity also varies with socioeconomic position (SEP). Few studies have examined if ambient air pollution has a differential impact on income subgroups of the population. This paper investigates socioeconomic variation in ambulatory physician consultations for asthma and assesses possible effect modification of SEP on the association between physician visits and air pollution for children aged 1-17 and adults aged 18-64 in Toronto, Canada, between 1992 and 2001.

Methods

Generalized additive models and generalized linear models were used to estimate the adjusted risk of asthma physician visits associated with an interquartile range increase in sulfur dioxide (SO₂), nitrogen dioxide (NO₂), particulate matter (PM_2.5), and ozone (O₃).

Results

A socioeconomic gradient in the number of physician visits was observed among children and adults and both sexes. SO₂, NO₂, and PM_2.5 had positive associations with physician visits. The risk ratios for the low socioeconomic group were significantly greater than those for the high socioeconomic group in several of the models of SO₂ and PM_2.5.

Conclusions

These findings suggest increased ambulatory physician visits represent another component of the public health impact of urban air pollution. The burden of this impact may be borne disproportionately by those with lower SEP. Clarifying the role of SEP in altering susceptibility to the effects of air pollution is essential not only to inform revisions of ambient air quality standards, but also to design public health interventions to reduce health impacts on sensitive subgroups of the population.     

Mortality in the Medicare Population and Chronic Exposure to Fine Particulate Air Pollution in Urban Centers (2000–2005)

Background

Prospective cohort studies constitute the major source of evidence about the mortality effects of chronic exposure to particulate air pollution. Additional studies are needed to provide evidence on the health effects of chronic exposure to particulate matter ≤ 2.5 μm in aerodynamic diameter (PM_2.5) because few studies have been carried out and the cohorts have not been representative.

Objectives

This study was designed to estimate the relative risk of death associated with long-term exposure to PM_2.5 by region and age groups in a U.S. population of elderly, for the period 2000–2005.

Methods

By linking PM_2.5 monitoring data to the Medicare billing claims by ZIP code of residence of the enrollees, we have developed a new retrospective cohort study, the Medicare Cohort Air Pollution Study. The study population comprises 13.2 million participants living in 4,568 ZIP codes having centroids within 6 miles of a PM_2.5 monitor. We estimated relative risks adjusted by socioeconomic status and smoking by fitting log-linear regression models.

Results

In the eastern and central regions, a 10-μg/m³ increase in 6-year average of PM_2.5 is associated with 6.8% [95% confidence interval (CI), 4.9–8.7%] and 13.2% (95% CI, 9.5–16.9) increases in mortality, respectively. We found no evidence of an association in the western region or for persons ≥ 85 years of age.

Conclusions

We established a cohort of Medicare participants for investigating air pollution and mortality on longer-term time frames. Chronic exposure to PM_2.5 was associated with mortality in the eastern and central regions, but not in the western United States.     

Seasonal effects of PM10 concentrations on mortality in Tianjin, China: a time-series analysis

Aim

There are uncertainties regarding the modification effects of season and temperature on the relationship between air pollution and mortality. This study aims to examine the effects of season and temperature on mortality associated with particulate matter less than 10 μm in diameter (PM₁₀) in Tianjin, China.

Methods

Time-series analysis was used to explore the modification effects of season and temperature on the association between PM₁₀ and cause-specific mortality in Tianjin between 2006 and 2009. The causes studied were overall non-accidental mortality and subcategories of cardiovascular, respiratory, cardiopulmonary, stroke, and ischemic heart diseases (IHD).

Results

The association between PM₁₀ and mortality showed a strong seasonal pattern and the effects of PM₁₀ on cause-specific mortalities were strongest for high temperature days. Generally, the adverse effects were stronger in summer than for other seasons, except for respiratory mortality. In the summer period, a 10 μg/m³ increase in PM₁₀ at 0–1 days was associated with an increase in mortality for non-accidental (0.95 %, 95 % confidence interval [CI]: 0.45, 1.45), cardiovascular (1.40 %, 95 %CI: 0.77, 2.03), cardiopulmonary (1.37 %, 95 %CI: 0.77, 1.98), IHD (1.55 %, 95 %CI: 0.73, 2.37), and stroke (1.27 %, 95 % CI: 0.37, 2.12) causes. The overall increase in mortality per 10 μg/m³ increase in PM₁₀ was 0.42 % (95 %CI: 0.26, 0.58) for non-accidental, 0.41 % (95 %CI: 0.21, 0.62) for cardiovascular, 0.46 % (95 %CI: 0.26,0.65) for cardiopulmonary, 0.57 % (95 %CI: 0.30, 0.84) for IHD, and 0.32 % (95 %CI: 0.03,0.61) for stroke. At high temperatures (≥23.8 °C), a 10 μg/m³ increase in PM₁₀ at 0–1 days was associated with an increase in mortality of 0.90 % (95 %CI: 0.61,1.19) for non-accidental, 1.01 % for cardiovascular, 1.40 % (95 %CI: 0.55, 2.27) for respiratory, 1.06 % (95 %CI: 0.71, 1.41) for cardiopulmonary, 1.47 % (95 %CI: 1.00, 1.94) for IHD, and 0.75 % (95 %CI: 0.24, 1.28) for stroke. In addition, the PM₁₀ effects of high temperature days were stronger for those aged 65 years and over.

Conclusion

Season and temperature could modify the adverse effects of PM₁₀. An increase in hot summer days caused by climate change may enhance the risks of air pollution on human health. More attention should be paid to older populations, especially in summer and days with high temperatures.     

Ambient ozone concentration and hospital admissions due to childhood respiratory diseases in New York State, 1991-2001

Background and objective

Respiratory diseases constitute one of the leading causes of ill health among children in New York State (NYS). The current project, a component of the NYS Environmental Public Health Tracking Program, investigated a potential association between ambient ozone (O₃) concentration and childhood respiratory hospital admissions over 11 years in NYS.

Methods

We used a two-stage Bayesian hierarchical model to assess the exposure-disease associations within 11 geographic regions and statewide. The data included total daily hospital admissions due to respiratory diseases for children 0-17 years old from 1991 to 2001 in NYS (N=134,099) and daily ambient O₃ level with different single-day lags. These analyses adjusted for particulate matter ?10 μm in size (PM₁₀), meteorological conditions, day of the week, seasonality, long-term trends, and demographic characteristics.

Results

In 5 of the 11 regions, including the Upper and Lower Adirondacks, Upper Hudson Valley, Staten Island, and New York City, positive associations were found between respiratory hospital admissions and ambient O₃ level 2 days prior to the admission. Applying different statistical methods and sensitivity analysis of PM₁₀ did not alter these findings. When region-specific results were combined, no statewide association was apparent.

Conclusions

Geographic differences were found in the associations between O₃ levels and respiratory hospital admissions among children. In addition, we found that the two-stage model may be an appropriate approach for tracking the health effects of air pollution over time in different geographic areas when heterogeneity of risk factors across regions is present.     

Effect of the interaction between outdoor air pollution and extreme temperature on daily mortality in Shanghai, China

Background

Both outdoor air pollution and extreme temperature have been associated with daily mortality; however, the effect of their interaction is not known.

Methods

This time-series analysis examined the effect of the interaction between outdoor air pollutants and extreme temperature on daily mortality in Shanghai, China. A generalized additive model (GAM) with penalized splines was used to analyze mortality, air pollution, temperature, and covariate data. The effects of air pollutants were stratified by temperature stratum to examine the interaction effect of air pollutants and extreme temperature.

Results

We found a statistically significant interaction between PM₁₀/O₃ and extreme low temperatures for both total nonaccidental and cause-specific mortality. On days with “normal” temperatures (15th–85th percentile), a 10-µg/m³ increment in PM₁₀ corresponded to a 0.17% (95% CI: 0.03%, 0.32%) increase in total mortality, a 0.23% (0.02%, 0.44%) increase in cardiovascular mortality, and a 0.26% (−0.07%, 0.60%) increase in respiratory mortality. On low-temperature days (<15th percentile), the estimates changed to 0.40% (0.21%, 0.58%) for total mortality, 0.49% (0.13%, 0.86%) for cardiovascular mortality, and 0.24% (−0.33%, 0.82%) for respiratory mortality. The interaction pattern of O₃ with lower temperature was similar. The interaction between PM₁₀/O₃ and lower temperature remained robust when alternative cut-points were used for temperature strata.

Conclusions

The acute health effects of air pollution might vary by temperature level.Key words: air pollution, climate change, extreme temperature, interaction, time-series     

Does over-exposure to copper ions released from metallic copper induce cytotoxic and genotoxic effects on mammalian cells?

Background

A high dissolution of copper from intrauterine devices (IUDs) occurs during the first days after insertion. This work is focused on the assessment of the possible cyto- and genotoxic effects of different concentrations of copper ions released from metallic copper on mammalian cells in vitro.

Study Design

Colorimetric tetrazolium/Trypan blue (TB) tests and Comet assay were used to evaluate potential cytotoxicity and genotoxicity, respectively, in Chinese hamster ovary cells (CHO-K1).

Results

Reduction of mitochondrial activity by copper ions was observed for extracts at ≥7.42 mg/L concentrations, while TB exclusion test for plasma membrane integrity showed significant decrease in cell viability (close to 90%) for 10.85 mg/L concentration. Additionally, copper-induced DNA damage was detected for 5.67-7.42 mg/L concentration range.

Conclusion

Our results demonstrate cytotoxic and genotoxic effects of copper ions released from metallic copper on CHO-K1 cells and emphasize the importance of reducing the initial copper dissolution from IUD without affecting the contraceptive action.     

Breast cancer screening for women ages 50 to 69 years a systematic review of observational evidence

Objective

To systematically review the observational evidence concerning the effect of screening on breast cancer mortality in actual populations of women ages 50-69 years.

Methods

We searched MEDLINE and multiple reference lists for relevant cohort and ecologic studies. At least 2 authors reviewed abstracts and full texts of studies meeting eligibility criteria. We rated each accepted study on standard quality criteria and developed a Summary Evidence Table.

Results

Seventeen studies met eligibility criteria. Five studies found no to small effect of screening (0-12% relative risk reduction [RRR] in breast cancer mortality), 4 found a large effect (greater than 33% RRR), and 8 found a moderate effect (13% to 33% reduction). The authors found concerns about quality in all studies. There was insufficient evidence to determine whether the effectiveness of screening is decreasing over time.

Conclusions

Current observational evidence shows that breast cancer screening in actual populations of women ages 50 to 69 reduces breast cancer mortality; the magnitude of the effect is probably smaller than predicted in the randomized controlled trials. Because the magnitude may change (either increase or decrease) in the future, further ecologic studies are needed. The methodology and infrastructure for these studies should be improved.     

The Effect of Fine and Coarse Particulate Air Pollution on Mortality: A National Analysis

Background

Although many studies have examined the effects of air pollution on mortality, data limitations have resulted in fewer studies of both particulate matter with an aerodynamic diameter of ≤ 2.5 μm (PM_2.5; fine particles) and of coarse particles (particles with an aerodynamic diameter > 2.5 and < 10 μm; PM coarse). We conducted a national, multicity time-series study of the acute effect of PM_2.5 and PM coarse on the increased risk of death for all causes, cardiovascular disease (CVD), myocardial infarction (MI), stroke, and respiratory mortality for the years 1999–2005.

Method

We applied a city- and season-specific Poisson regression in 112 U.S. cities to examine the association of mean (day of death and previous day) PM_2.5 and PM coarse with daily deaths. We combined the city-specific estimates using a random effects approach, in total, by season and by region.

Results

We found a 0.98% increase [95% confidence interval (CI), 0.75–1.22] in total mortality, a 0.85% increase (95% CI, 0.46–1.24) in CVD, a 1.18% increase (95% CI, 0.48–1.89) in MI, a 1.78% increase (95% CI, 0.96–2.62) in stroke, and a 1.68% increase (95% CI, 1.04–2.33) in respiratory deaths for a 10-μg/m³ increase in 2-day averaged PM_2.5. The effects were higher in spring. For PM coarse, we found significant but smaller increases for all causes analyzed.

Conclusions

We conclude that our analysis showed an increased risk of mortality for all and specific causes associated with PM_2.5, and the risks are higher than what was previously observed for PM₁₀. In addition, coarse particles are also associated with more deaths.     

Chronic Fine and Coarse Particulate Exposure,Mortality, and Coronary Heart Disease in the Nurses’ Health Study

Background

The relationship of fine particulate matter < 2.5 μm in diameter (PM_2.5) air pollution with mortality and cardiovascular disease is well established, with more recent long-term studies reporting larger effect sizes than earlier long-term studies. Some studies have suggested the coarse fraction, particles between 2.5 and 10 μm (PM_10–2.5), may also be important. With respect to mortality and cardiovascular events, questions remain regarding the relative strength of effect sizes for chronic exposure to fine and coarse particles.

Objectives

We examined the relationship of chronic PM_2.5 and PM_10–2.5 exposures with all-cause mortality and fatal and nonfatal incident coronary heart disease (CHD), adjusting for time-varying covariates.

Methods

The current study included women from the Nurses’ Health Study living in metropolitan areas of the northeastern and midwestern United States. Follow-up was from 1992 to 2002. We used geographic information systems–based spatial smoothing models to estimate monthly exposures at each participant’s residence.

Results

We found increased risk of all-cause mortality [hazard ratio (HR), 1.26; 95% confidence interval (CI), 1.02–1.54] and fatal CHD (HR = 2.02; 95% CI, 1.07–3.78) associated with each 10-μg/m³ increase in annual PM_2.5 exposure. The association between fatal CHD and PM_10–2.5 was weaker.

Conclusions

Our findings contribute to growing evidence that chronic PM_2.5 exposure is associated with risk of all-cause and cardiovascular mortality.     

Digital mammography screening: weighing reduced mortality against increased overdiagnosis

Objective

Digital mammography has been shown to increase the detection of ductal carcinoma in situ (DCIS) compared to screen-film mammography. The benefits and risks of such an increase were assessed.

Methods

Breast cancer detection rates were compared between 502,574 screen-film and 83,976 digital mammograms performed between 2004 and 2006 among Dutch screening participants. The detection rates were then modeled using a baseline model and two extreme models that respectively assumed a high rate of progression and no progression of preclinical DCIS to invasive cancer. With these models, breast cancer mortality and overdiagnosis were predicted.

Results

The DCIS detection rate was significantly higher at digital mammography (1.2 per 1000 mammograms (95% C.I. 1.0-1.5)) than at screen-film mammography (0.7 per 1000 mammograms (95% C.I. 0.6-0.7)). Consequently, 287 (range progressive- non progressive model: 1-598) extra breast cancer deaths per 1,000,000 women (a 4.4% increase) were predicted to be prevented. An extra 401 (range: 165-2271) cancers would be overdiagnosed (a 21% increase).

Conclusion

Modeling predicted that digital mammography screening would further reduce breast cancer mortality by 4.4%, at a 21% increased overdiagnosis rate. The consequences of digital screening, however, are sensitive to underlying assumptions on the natural history of DCIS.