Increment In PM2 Research Articles

The impact of noise on the short-term effects of traffic-related air pollution on heart rate variability in young healthy adults

Background: Traffic-related air pollution and noise are associated with cardiovascular diseases, and the alternation of heart rate variability (HRV), which reflects cardiac autonomic function, is considered as one of the mechanisms. However, few studies have explored interaction effects between traffic-related air pollution and noise on HRV. Aims: We explored whether noise modified the associations between short-term exposure to traffic-related air pollution and HRV in young healthy adults. Methods: In this randomized, crossover study, 40 young healthy adults stayed for 2 hours in a traffic center, and on a separate occasion, in a park. Subjects underwent ambulatory electrocardiogram monitoring and their personal exposure to fine particle (PM2.5), black carbon (BC), carbon monoxide (CO) and noise were measured. Mixed-effects regression models were applied for analysis, and interaction effects were assessed. Results: Traffic-related air pollution and noise were negatively associated with HRV separately, and the effects of traffic-related air pollutants were amplified at high noise level (>65.6 dBA) compared with low noise level (?65.6 dBA). Per 10 ?g/m3 increment in PM2.5 (5-minute moving average) was associated with ?4.61% (95% CI, ?6.75% to ? 2.42%) decrease in high frequency (HF) power, however the correlations became insignificant at low noise level. Per 1 ?g/m3 increment in BC (1-hour average) was associated with ?2.59% (95% CI, ?4.43% to ?0.72%) decrease in HF at high noise level, compared with ?2.20% (95% CI, ?3.56% to ?0.81%) at low noise level. Similar effects modification was observed for CO exposure. Conclusions: Both traffic-related air pollutants and noise associated with imbalanced cardiac autonomic function. The effects of air pollutants were amplified at high noise level.

WHAT IS THE BEST INDICATOR OF THE ADVERSE HEALTH EFFECTS OF COMBUSTION PARTICLES: BLACK CARBON OR PARTICLE MASS?

Background and Aims: Current air quality standards for particulate matter use the mass concentration (PM10 or PM2.5) as a metric. It has been suggested that particles from combustion sources are more health relevant. Expressed in reduction of the total mass concentration the impact of policies directed at reducing particles from combustion processes is usually relatively small. We therefore evaluated the value of black carbon particles (BCP) as an additional indicator in air quality management. Methods. We consider different measurement methods for BCP and compare the near roadway concentration gradients of BCP with those of PM mass. We review the evidence comparing the health effects of BCP with those of PM mass. We compare the potential health benefits of a hypothetical traffic abatement measure calculated based on concentrations response functions for BCP with those based on PM2.5. Results. Near roadway concentration gradients are much steeper for BCP than for PM mass. A relatively large part (40-70%) of the roadside increment in PM2.5 mass concentrations can be attributed to BCP. Health effect estimates from mortality and morbidity time-series studies as well as cohort studies were higher for BCP than for PM10 or PM2.5 when expressed per μg/m3. When applying the calculated Relative Risks (RR) for all cause mortality from cohort studies, the increase in life expectancy associated with a hypothetical traffic abatement measure was four to nine times higher when expressed per achievable reduction in BCP compared to that per an equivalent amount of PM2.5 mass. Conclusion. BCP is a valuable additional air quality indicator to evaluate the health risks of air quality dominated by primary combustion particles

EXPOSURE TO PARTICULATE AIR POLLUTION AND COGNITIVE DECLINE IN OLDER WOMEN

Results: Higher levels of long-term exposure to both PM2.5-10 and PM2.5 were associated with significantly faster cognitive decline. Two-year decline on a global score was 0.020 (95% CI, �0.032 to �0.008) standard units worse per 10 µg/m 3 increment in PM2.5-10 exposure and 0.018 (95% CI, �0.035 to �0.002) units worse per 10 µg/m 3 increment in PM2.5 exposure. These differences in cognitive trajectory were similar to those between women in our cohort who were approximately 2 years apart in age, indicating that the effect of a 10-µg/m 3 increment in longterm PM exposure is cognitively equivalent to aging by approximately 2 years. Conclusion: Long-term exposure to PM2.5-10 and PM2.5 at levels typically experienced by many individuals in the United States is associated with significantly worse cognitive decline in older women.

Ambient Particulate Matter Exposure and Hypertension Incidence in the Multiethnic Study of Atherosclerosis

PP-29-039 Background/Aims: Despite evidence of a cross-sectional association between ambient fine particulate matter (PM2.5) and high blood pressure, no population-based study has explored the association of fine particle exposure with incident hypertension. This study examined whether ambient PM2.5 is associated with hypertension incidence. Methods: The study included 3006 participants, aged 45–84 years and without hypertension (systolic blood pressure ≥140 mm Hg, diastolic blood pressure ≥90 mm Hg, or on antihypertensive medications) at the baseline examination (2000–2002) of the Multiethnic Study of Atherosclerosis. Annual average PM2.5 concentrations at participant residences were calculated for 2001 using a spatio-temporal model and used as a proxy for exposure over the 5-year follow-up period. Incident hypertension was defined by participant's SBP ≥ 140 mm Hg, DBP ≥ 90 mm Hg, or on antihypertensive medications at follow-up visits. Hazard ratios of incident hypertension per 10 μg/m3 increment in PM2.5 were estimated using interval censored survival analysis, adjusting for age, sex, race/ethnicity, systolic blood pressure, diastolic blood pressure, body mass index, diabetes, smoking, passive smoking, alcohol use, healthy diet index, and physical activity at baseline. Results: A total of 825 new cases of hypertension occurred over the 5-year follow-up. The mean estimated PM2.5 exposure was 17.3 μg/m3 (standard deviation, 3.2 μg/m3). For each 10 μg/m3 increment of PM2.5, the adjusted hazard ratio for incident hypertension was 1.22 (95% confidence interval, 0.93–1.59). The point estimate of association remained positive and not statistically significant after further adjustment for study site and socioeconomic status (income and education) at baseline. Conclusion: Results from our study sample provide only weak support to the hypothesis that exposure to ambient fine particulate air pollution may contribute to onset of hypertension.

Fine (PM2.5) and Coarse (PM2.5-10) Particulate Matter on A Heavily Trafficked London Highway: Sources and Processes

A large dataset for PM2.5 and PMcoarse (PM2.5-10) concentrations monitored near a busy London highway (Marylebone Road) has been analyzed to define the factors that lead to high concentrations. The following have been highlighted as major influencing parameters: wind speed, prevailing wind direction (because of its role on the microscale dispersion within the street), the daily cycle of the atmospheric boundary layer (stable during the night/ convective and mixed during the day), and traffic density. The mainly diesel heavy-duty vehicles are the main source of fine particulate matter at Marylebone Road. In particular, lorries (trucks) dominate PM10 exhaust emissions which are mainly in the fine (<2.5 microm) size range. A strong correlation with PMcoarse suggests that the heavy-duty traffic is largely responsible for this component also. Substantial local increments in PM2.5 and PMcoarse due to traffic have been estimated and a large part of the increment in PMcoarse concentrations is inferred to arise from resuspended road dust emissions since the contribution of abrasion processes estimated from emission factors is modest. Despite the strong influence of traffic on PM concentrations measured at Marylebone Road the analysis of factors leading to the highest 5% of hourly concentrations of PM10 at Marylebone Road reveals that almost half of these events were due to building works. The other events occurred when all or most of the key factors occurred simultaneously (heavy traffic, poor dispersion, etc.). Some episodes of high PM2.5 concentrations were associated with long-range transport in which the regional PM2.5 constituted most of the local concentrations.

A STUDY ON THE ACUTE EFFECTS OF AMBIENT AIR PARTICLES ON PULMONARY FUNCTION OF CHINESE SCHOOLCHILDREN

ISEE-49 Introduction: As information about the health risks associated with air pollution has become available, attention has focused increasingly on smaller air particles such as particulate matter with an aerodynamic diameter to or less than a 10 or 2.5u (PM10 or PM2.5, respectively). A number of recent studies conducted in Asia, Europe and the United States have shown that acute exposure to current levels of air particles is associated with adverse health status, including mortality, hospital admissions due to asthma, severity of preexisting chronic illness, low birth weight and pulmonary functions. Our objective was to evaluate the acute effects of ambient air particles on pulmonary function. Methods: This study was directed at the schoolchildren (3rd and 6th grades) living in a Beijing, China. Each child was provided with a mini-Wright peak flow meter and a preformatted health symptom diary for 40 days, and was trained on their proper use. Participants were instructed to perform the peak flow test three times in the standing position, three times daily (9 am, 12 pm, and 8 pm), and to record all the readings along with the symptoms (cold, cough, and asthmatic symptoms) experienced that day. Daily measurement of ambient air particles (PM10 and PM2.5) was obtained in the corner of the playground of the participating elementary school for the same period of this longitudinal study. The relationship between daily PEFR and ambient air particle levels was analyzed using a mixed linear regression models including gender, height, the presence of respiratory symptoms, and daily average temperature and relative humidity as an extraneous variable. Results: The total number of subjects participating in this longitudinal study was 87. The range of daily measured PEFR in this study was 253 to 501 L/min. In general, a PEFR measured in the morning was lower than a PEFR measured in the evening (or afternoon) on the same day. The daily mean concentrations of PM10 and PM2.5 over the study period were 180.2 ug/m3 and 103.2 ug/m3, respectively. The IQR (inter-quartile range) of PM10 and PM2.5 were 91.8 ug/m3 and 58.0 ug/m3. During the study period, the national ambient air quality standard of 150 ug/m3 was exceeded in 23 days (57.5%), which shows that the pollutant status of PM10 is very serious in the study area. The analysis showed that an increase of 1 ug/m3 of PM10 corresponded to 0.59 ug/m3 increment of PM2.5. Daily mean PEFR was regressed with the 24-hour average PM10 (or PM2.5) levels, weather information such as air temperature and relative humidity, and individual characteristics including gender, height, and respiratory symptoms. The analysis showed that the increase of air particle concentrations was negatively associated with the variability in PEFR. We estimated that the IQR increment of PM10 or PM2.5 (at the time lag 1 day) were associated with 1.54 L/min (95% Confidence intervals −2.14, −0.94) and 1.56 L/min (95% CI −2.16, −0.95) decline in PEFR. Conclusions: Our objective was to evaluate the relationship between ambient air particles and lung function measured by peak expiratory flow rate (PEFR) among school children. We conducted a community-based diary study and used a classic design for the respiratory effects of ambient air particles and used longitudinal information for 40 days of follow-up starting from March 25, 2003 to May 3, 2003. The relationship between daily PEFR and ambient air particle levels was analyzed using a mixed linear regression models including gender, height, the presence of respiratory symptoms, and daily average air temperature and relative humidity as an extraneous variable. In conclusion, we found a significant association between outdoor levels of particulate matter and PEFR, and estimated that the IQR increment of PM10 or PM2.5 (91.8 ug/m3, 58.0 ug/m3, respectively) were significantly associated with 1.54 L/min and 1.56 L/min decline in PEFR.

Do associations between airborne particles and daily mortality in Mexico City differ by measurement method, region, or modeling strategy?

We evaluated whether associations between PM10 and daily mortality in Mexico City differ by the PM10 measurement device or by regional differences in particle composition. Additionally, we reanalyzed previously collected data in light of recent insights about flaws in commonly used time series analysis techniques. We examined daily associations between mortality and four indicators of ambient PM10 using Poisson regression, controlling for temperature and time trends with cubic natural splines. Associations were calculated for five subregions corresponding to five monitoring sites and pooled for the entire metropolitan area. PM10 was measured with three methods: Tapered Element Oscillating Microbalance (TEOM), Sierra-Anderson High Volume (Hi-Vol) and Harvard Impactor (HI), the latter only at one site. In addition, predicted values of daily PM10 were developed using the Hi-Vol measurements, which were taken every sixth day, and weather, visibility and other pollutant data. We assigned deaths to the exposure from the monitor nearest to their residence. We also re-evaluated the HI PM2.5 and mortality association in southwest Mexico City, which was estimated previously using nonparametric statistical models. Slight decreases in effect estimates were observed (a 1.45% increase (95% CI: 0.09%, 2.83%) in total mortality per 10 microg/m(3) increment of PM2.5 at lag 0) compared to a 1.68% change (95% CI: 0.45%, 2.93%) using the previously employed nonparametric approach. Using data pooled over all the regions, PM10 measured by the TEOM and the predicted PM10 values showed little association with mortality at any of the lags examined. The pooled estimates for Hi-Vol PM10 (using one sixth of the data) were positive across all lags examined and significant for lags 3 and 5. No consistent patterns of differing associations were seen across regions that would correspond with particle toxicity or composition. Particulate air pollution, measured with gravimetric methods, is associated with daily mortality and presents a risk to health in Mexico City. The reanalysis suggests that previous research is robust to statistical method and likely to yield the same overall conclusions about the short-term effects of airborne particles on mortality.

Particulate matter and heart rate variability among elderly retirees: the Baltimore 1998 PM study.

This study investigates the relationship between ambient fine particle pollution and impaired cardiac autonomic control in the elderly. Heart rate variability (HRV) among 56 elderly (mean age 82) nonsmoking residents of a retirement center in Baltimore County, Maryland, was monitored for 4 weeks, from July 27 through August 22, 1998. The weather was seasonally mild (63-84 degrees F mean daily temperature) with low to moderate levels of fine particles (PM2.5 < 50 micrograms/m3). Two groups of approximately 30 subjects were examined on alternate days. A spline mixed-effects model revealed a negative relationship between outdoor 24-h average fine particulate matter (PM2.5) and high-frequency (HF) HRV that was consistent with our earlier Baltimore study for all but 2 days. These 2 days were the only days with significant precipitation in combination with elevated PM2.5. They were also unusual in that back-trajectory of their air masses was distinctly different from those on the other study days, emanating from the direction of rural Pennsylvania. Mixed-effects analysis for all 24 study days showed a small negative association of outdoor PM2.5 with HF HRV (-0.03 change in log[HF HRV] for a 10 micrograms/m3 increment in PM2.5) after adjustment for age, sex, cardiovascular status, trend, maximum temperature, average dew point temperature, random subject intercepts, and autocorrelated residuals. After excluding study days 4 and 5, this association was strengthened (-0.07 change in log[HF HRV] for 10 micrograms/m3 PM2.5, 95% CI -0.13 to -0.02) and was similar to that obtained in an earlier study (-0.12 change in log[HF HRV] for a 10 micrograms/m3 increment in outdoor PM2.5, 95% CI -0.24 to -0.00) [Liao D., Cai J., Rosamond W.D., Barnes R.W., Hutchinson R.G., Whitsel E.A., Rautaharju P., and Heiss G. Cardiac autonomic function and incident coronary heart disease: a population-based case-cohort study. The ARIC Study. Atherosclerosis Risk in Communities Study. Am J Epidemiol 1997: 145 (8): 696-706]. Acute (1 to 4 h) previous PM2.5 exposure did not have a stronger impact than the 24-h measure. A distributed lag model incorporating the six preceding 4-h means also did not indicate any effect greater than that observed in the 24-h measure. This study is consistent with earlier findings that exposures to PM2.5 are associated with decreased HRV in the elderly.

Airborne Coarse Particles and Mortality

Some recent epidemiologic studies suggest a stronger effect of fine particles (PM2.5) than of coarser particulate matter. To examine the support for such a differential effect, the authors conducted a daily time-series analysis of mortality in relation to measurements of PM2.5, PM10, and PM10-2.5 in southwestern Mexico City in the years 1992–1995. A generalized linear model based on Poisson regression was used to control for weather and periodic cycles, and the average concentration of the previous five days was the index of particle exposure. The mean concentrations of PM 2.5 and PM10 were 27.4 μg m−3 and 44.6 μg m-3, respectively, and the mean concentration of PM10-2.5 was 17.2 μg m-PM10 was highly correlated with both the fine and coarse fractions, but PM 2.5 and PM 10–2.5 were rather weakly correlated with each other (correlation coefficient 0.52). All three particle size fractions were associated individually with mortality: a 10-μg m3 increase in PM10 Supported by cooperative agreements CR-820076 and CR-821762 between the U.S. Environmental Protection Agency and the University of North Carolina and Harvard University Schools of Public Health and a grant from the Mexico-U.S. Commission for Educational and Cultural Exchange. We thank Bill McDonnell, Armando Retama, Daniel Varela, and Silvia Bierswinski for contributions to the research and comments on the manuscript. Address correspondence to Dr. Dana Loomis, Department of Epidemiology, CB-7400, School of Public Health, University of North Carolina, Chapel Hill, NC 27599–7400, USA. E-mail: dana.loomis@unc.edu was associated with a 1.83% increase in total mortality (95% CI −0.01-2.96), and an equal increment in PM2.5 was associated with a 1.48% increase in deaths (95% CI 0.98-2.68%). The largest effect was observed for a 10 μg m−3 increment in PM 10-2.5; mean daily mortality increased 4.07% for each 10 μg m−3 (95% CI 2.49-5.66%). The effect of coarse particles was stronger for respiratory diseases than for total mortality, cardiovascular diseases, or other noninjury causes of death. These patterns persisted after adjustment (or O3 and NO2. When both PM2.5 and PM 10-2.5 were included simultaneously in the regression model, the effect of PMW-2.5 remained about 4% per 10 μg m−3 (95% CI 1.96-6.02%), while the effect of PM2.5 was virtually eliminated (0.18% change). These associations may be attributable to specific combustion or biogenic materials within the coarse particle mass. Understanding these relationships will require analyses of the composition of coarse particles. The findings also suggest a need to that the relative effects of coarse and fine particles on mortality should be examined in more cities with a wider variety of climates, population characteristics, and air pollutants.