Effects of airborne particulate matter on respiratory morbidity in asthmatic children

Background

The effects of airborne particulate matter (PM) are a major human health concern. In this panel study, we evaluated the acute effects of exposure to PM on peak expiratory flow (PEF) and wheezing in children.

Methods

Daily PEF and wheezing were examined in 19 asthmatic children who were hospitalized in a suburban city in Japan for approximately 5 months. The concentrations of PM less than 2.5 µm in diameter (PM_2.5) were monitored at a monitoring station proximal to the hospital. Moreover, PM_2.5 concentrations inside and outside the hospital were measured using the dust monitor with a laser diode (PM_2.5(LD)). The changes in PEF and wheezing associated with PM concentration were analyzed.

Results

The changes in PEF in the morning and evening were significantly associated with increases in the average concentration of indoor PM_2.5(LD) 24 h prior to measurement (-2.86 L/min [95%CI: -4.12, -1.61] and -3.59 L/min [95%CI: -4.99, -2.20] respectively, for 10-µg/m³ increases). The change in PEF was also significantly associated with outdoor PM_2.5(LD) concentrations, but the changes were smaller than those observed for indoor PM_2.5(LD). Changes in PEF and concentration of stationary-site PM_2.5 were not associated. The prevalence of wheezing in the morning and evening were also significantly associated with indoor PM_2.5(LD) concentrations (odds ratios = 1.014 [95%CI: 1.006, 1.023] and 1.025 [95%CI: 1.013, 1.038] respectively, for 10-µg/m³ increases). Wheezing in the evening was significantly associated with outdoor PM_2.5(LD) concentration. The effects of indoor and outdoor PM_2.5(LD) remained significant even after adjusting for ambient nitrogen dioxide concentrations.

Conclusion

Indoor and outdoor PM_2.5(LD) concentrations were associated with PEF and wheezing among asthmatic children. Indoor PM_2.5(LD) had a more marked effect than outdoor PM_2.5(LD) or stationary-site PM_2.5.Key words: Particulate Matter, Asthma, Peak Expiratory Flow Rate, Respiratory Sounds     

PM_(2.5)个体暴露连续监测方法

目的整合滤膜称重法和光散射法测定PM_(2.5)优越性,建立更加准确的PM_(2.5)个体暴露连续监测方法。方法采用滤膜称重法和光散射法同时测定个体PM_(2.5)暴露浓度,以滤膜称重法与光散法测定结果的比值作为校正系数,修正光散射法测定值,获得PM_(2.5)个体暴露实时浓度。结果测定时间为3、10、30和60 min时方法检出限(LOD)分别4.6、4.0、3.9和3.7μg/m~3;对不同浓度环境空气平行测定的精密度(RSD)范围为2.1%~9.5%;与微量振荡天平法(TEOM)测定的实时浓度(30min时间加权平均浓度)间具有良好的相关关系,Pearson r=0.934(P0.001,n=233),配对t检验结果表明两种方法结果间差异无统计学意义(P=0.957);实验室连续24 h监测中,30%(3/10)的监测检测到零点漂移,漂移值范围为-5~-3μg/m~3;连续5 d的现场监测中,7.5%(31/412)的监测检测到零点漂移,其中大部分的漂移值在-3~3μg/m~3,零点漂移方向和大小不受环境PM_(2.5)浓度影响。结论该方法结合了光散射法及重量法的优点,可以获得较为准确的PM_(2.5)个体实时暴露浓度,能够满足PM_(2.5)个体暴露监测的要求。     

Elevated personal exposure to particulate matter from human activities in a residence

Continuous laser particle counters collocated with time-integrated filter samplers were used to measure personal, indoor, and outdoor particulate matter (PM) concentrations for a variety of prescribed human activities during a 5-day experimental period in a home in Redwood City, CA, USA. The mean daytime personal exposures to PM(2.5) and PM(5) during prescribed activities were 6 and 17 times, respectively, as high as the pre-activity indoor background concentration. Activities that resulted in the highest exposures of PM(2.5), PM(5), and PM(10) were those that disturbed dust reservoirs on furniture and textiles, such as dry dusting, folding clothes and blankets, and making a bed. The vigor of activity and type of flooring were also important factors for dust resuspension. Personal exposures to PM(2.5) and PM(5) were 1.4 and 1.6 times, respectively, as high as the indoor concentration as measured by a stationary monitor. The ratio of personal exposure to the indoor concentration was a function of both particle size and the distance of the human activity from the stationary indoor monitor. The results demonstrate that a wide variety of indoor human resuspension activities increase human exposure to PM and contribute to the "personal cloud" effect.     

Association between exposure to particulate matter and hospital admissions for respiratory disease in children

The aim of this study was to estimate the association between exposure to particulate matter less than 2.5 microns in diameter and hospitalization for respiratory disease. It was an ecological time series study with daily indicators of hospitalization for respiratory diseases in children up to 10 years old, living in Piracicaba, SP, Southeastern Brazil, between August 1, 2011 and July 31, 2012. A generalized additive Poisson regression model was used. The relative risks were RR = 1.008; 95%CI 1.001;1.016 for lag 1 and RR = 1.009; 95%CI 1.001;1.017 for lag 3. The increment of 10 μg/m³in particulate matter less than 2.5 microns in diameter implies increase in relative risk of between 7.9 and 8.6 percentage points. In conclusion, exposure to particulate matter less than 2.5 microns in diameter was associated with hospitalization for respiratory disease in children.     

Employee exposure to airborne fiber and total particulate matter in two mineral wool facilities

Two facilities, one producing rock wool by retort melting with subsequent fiber formation by spinning (Plant A), and the other utilizing slag, glass scrap, and fly ash in a reverbatory furnace to form a melt which is spun (Plant B), were surveyed for dust exposures of employees. A variety of products was manufactured in each plant. The surveys were performed by dividing each facility into “dust zones” on the basis of the processing operations, ventilation methods, or employee jobs. Representative men in each job title associated with each “dust zone” wore personal dust sampling filters and air pumps for an entire work shift. A total of 63 samples was collected in Plant A and 72 in Plant B. Samples of dust on filters were analyzed to determine weight of total dust in the air, expressed as milligrams per cubic meter, and fiber concentrations, expressed as fibers per cubic centimeter in two diameter ranges, greater than 1 μm and less than 1 μm. Phase contrast and electron microscopic methods were utilized for the latter two analyses, respectively. Fiber length and diameter distributions were also determined. Electron microscopic analyses followed ashing of samples; each fiber observed was subjected to an intense beam to determine crystalline or amorphous structure by the presence or absence of a diffraction pattern. The ranges of Total Suspended Particulate Matter (TSPM) concentrations in Plants A and B were 0.53–23.64 and 0.045–6.88 mg/m³, respectively. In Plant A, Tile Finishing and Warehouse were the dustiest zones; in Plant B, Maintenance and Main Plant zones were the dustiest. Average fiber concentrations (>1 μm diameter) determined by phase contrast microscopy ranged from 0.20–1.4 fibers/cm³ in Plant A and from 0.011–0.43 fibers/cm³ in Plant B. The average concentrations of fibers less than 1 μm diameter, as determined by electron microscopy, ranged from 0.0056 to 0.16 fibers/cm³ in Plant A and from 0.0059 to 0.089 fibers/cm³ in Plant B. The percentage of respirable fibers, those less than 3 μm diameter, as determined by phase contrast microscopy, was approximately 75% of all airborne fibers in both plants. Estimates of fiber weight suggest that fibers contribute from 0.11 to 4.3% of TSPM for samples collected in Plant A, and from 0.8 to 57.8% of TSPM for samples collected in Plant B. Thus, fibers, defined to be particles with at least a 3:1 aspect ratio, represent a small fraction of airborne particles to which employees in these plants are exposed. In both facilities the weight concentration of total airborne dust, expressed as milligrams per cubic meter, was a poor indicator of airborne fiber concentration, expressed as fibers per cubic centimeter and determined by either phase contrast microscopy (fibers > 1 μm diameter) or electron microscopy (fibers < 1 μm diameter).     

Prospective evaluation of respiratory health benefits from reduced exposure to airborne particulate matter

We aimed to investigate if short-term exposure to reduced particulate matter (PM) air pollution would affect respiratory function in healthy adults. We followed a cohort of 42 healthy participants from a community afflicted with severe PM air pollution to a substantially less polluted area for nine days. We measured daily airborne PM [with an aerodynamic diameter of less than 2.5 μm (PM_2.5) and 10 μm (PM₁₀)] and PM_2.5 carbon component concentrations. Five repeated respiratory function measurements and fractional exhaled nitric oxide test were made for each participant. Associations between respiratory health and PM exposure were assessed using linear mixed models. Each 10 μg/m³ decrease in same-day PM_2.5 was associated with small but consistent increase in the forced expiratory volume in 1 s (FEV₁) (9.00 mL) and forced vital capacity (14.35 mL). Our observations indicate that respiratory health benefits can be achieved even after a short-term reduction of exposure to PM. Our results provide strong evidence for more rigorous air pollution controls for the health benefit of populations.     

Childhood respiratory symptoms, hospital admissions, and long-term exposure to airborne particulate matter

The effects of long-term exposure to air pollution on respiratory symptoms and respiratory hospitalization (for asthma, bronchitis or pneumonia) were assessed in a cross-sectional study of children (ages 7--11 years, N=667) living in a moderately industrialized city in Central Slovakia. Individual health, residence and family history data obtained through the CESAR study were coupled, using Geographic Information System (GIS) technologies, with total suspended particulate (TSP) exposure estimates derived from dispersion modeling of almost all local stationary sources. These data were used to assess, at the intra-city level and child-specific level, the potential for TSP as a risk factor for respiratory disease in children. TSP, PM10, and PM2.5 monitored ambient concentrations are highly correlated in the study location. Modeled TSP concentrations resulting from local source emissions are dominated by a large wood processing facility, suggesting variation in exposures among children. The prevalence of respiratory non-asthmatic symptoms and hospitalizations was associated with increased TSP. No association between long-term exposure to TSP and asthma diagnosis or wheeze symptoms was found. Logistic regression modeling indicated a significant increase in hospital admissions for asthma, bronchitis or pneumonia associated with increasing air pollution (OR 2.16, CI, 1.01--4.60), doctor-diagnosed bronchitis (OR 1.53, CI, 1.02-2.30), and parent-reported chronic phlegm (OR 3.43, CI, 1.64--7.16), expressed as odds for a 15 microg/m3 increase in estimated TSP exposure, and these increases are not due to differences in socio-economic, health care or other identified factors.     

Exposure to airborne particulate matter in Kathmandu Valley, Nepal

Kathmandu Valley, Nepal, has severe air pollution, although few studies examine air pollution and health in this region. To the best of our knowledge, no previous studies in Nepal used time-activity diaries or conducted personal monitoring of individuals' exposures. We investigated personal exposure of particulate matter (PM) with aerodynamic diameter ≤2.5 μm (PM(2.5)) by location, occupation, and proximity to roadways. PM(2.5) monitoring, time-activity diary, respiratory health questionnaire, and spirometer testing were performed from 28 June 2009 to 7 August 2009 for 36 subjects, including traffic police (TP), indoor officer workers next to main road (IOWs_NMR) and away from main road (IOWs_AMR), in urban area (UA), urban residential area, and semi-UA (SUA). TP had the highest exposure of all the occupations (average 51.2?μg/m(3), hourly maximum >500?μg/m(3)). TP levels were higher at the UA than other locations. IOW_NMR levels (averaged 46.9 μg/m(3)) were higher than those of IOW_AMR (26.2?μg/m(3)). Exposure was generally higher during morning rush hours (0800-1100 hours) than evening rush hours (1500-1800 hours) for all occupations and areas (78% of days for TP and 84% for urban IOW). PM(2.5) personal exposures for each occupation at each location exceeded the World Health Organization ambient PM(2.5) guideline (25?μg/m(3)). Findings suggest potential substantial health impacts of air pollution on this region, especially for TP.     

可吸入大气颗粒物暴露对居民每日死亡短期影响的Meta分析

目的综合分析国内外可吸人大气颗粒物（PM10）短期暴露与人群死亡关系的流行病学资料,以获取大气PM10污染与居民死亡的暴露一反应关系。方法在计算机联机检索文献和手工检索的基础上,对近十年来发表的相关研究文献采用meta分析的方法进行综合评价,并检验、校正可能存在的发表偏倚,从而准确、定量地确定PM10污染与居民死亡的暴露一反应关系。结果建立了居民短期接触大气PM10污染的暴露一反应关系,即在未考虑发表偏倚的情况下,大气中PM10每增加100μg/m^3,居民死亡的相对危险度增加3．87％（95％CI：2．84％～5．02％）,在校正了发表偏倚后大气中PM10每增加100p．μg／m^3,死亡的相对危险度增加下降为1．41％（95％CI：0．30％-2．43％）,与考虑偏倚前相比下降了63．6％。结论该研究建立的暴露-反应关系较早注意到发表偏倚的影响,具有一定的代表性与科学性,可用于大气颗粒物暴露健康危险度评价工作参考,为制定相关环境决策提供科学依据。     

妊娠期空气颗粒物暴露与早产

越来越多的研究证据表明,孕妇妊娠期颗粒物暴露可通过母体影响胎儿的发育,导致早产、低出生体重、胎儿生长受限和潜在的不良心血管和呼吸道结局。但研究结果并不一致,且生物学机制尚不明确。本文通过对近年来国内外主要几种颗粒物人体暴露来源和其对早产影响及生物学机制作一简要综述,为控制空气污染和减少早产等不良妊娠结局的发生以及进一步探讨其可能的生物学机制提供基础依据。     

Implications for occupational exposure to particulate matter

The demonstrated effects of lower levels of ambient particles on cardiovascular and respiratory system morbidity and mortality were initially surprising in light of current concepts of occupational particle exposure and acute and chronic cardiopulmonary effects. Specifically, the exposure levels, as defined by the weight of the particles per liter of breathing air, at which recognized disease occurs under workplace conditions are considerably higher than the observed levels of ambient particles associated with serious adverse health effects. The possible reasons for this difference have not been adequately addressed. To further address this question, a re-examination of workplace exposure-response relationships is needed, which may include emphasis on measuring exposures to fine and ultrafine particles rather than to total particle mass concentration alone.     

Monitoring of 1-min personal particulate matter exposures in relation to voice-recorded time-activity data.

Recent studies on the association between exposures to airborne particulate matter (PM) and disease have identified short-term peaks in PM exposures as posing especial health threats. Lightweight personal instruments are needed to characterize short-term exposures to PM and to identify the most important sources of high PM excursions. In this study, we measured exposure to fine PM using a small personal nephelometer (pDR; MIE, Inc) to investigate the utility of this instrument in identifying activities and microenvironments most associated with high PM exposures and the magnitude and duration of peaks in PM exposures. Ten adult volunteers wore a pDR recording PM concentrations at 1-min time intervals for 1 week each. PM concentrations were measured by the pDR in units of microg/m(3) based on light scatter. The use of a time-stamped voice recorder enabled activity and location to be continuously documented in real time. In addition, a small, inexpensive light intensity logger was affixed to the pDR to evaluate the potential of this instrument to assist in verifying wearer- recorded data. For each person, patterns of PM exposure were remarkably consistent over daily activities and showed large excursions associated with specific indoor and outdoor microenvironments and activities, such as cooking. When the magnitude and duration of excursions in PM were analyzed, we found that high PM levels occurred in relatively few of the minutes measured but comprised a substantial fraction of the total exposure to PM. Fifteen-minute averaged PM levels were found to be as much as 10 times the daily average. When the data were analyzed with a generalized estimating equation model to account for effects of autocorrelation and clustering, PM exposure was significantly higher during subject-reported events including barbeque, yard work, being near pets or construction activities, cooking, and environmental tobacco smoke exposure, as compared with periods with no pollution events. When light intensity data were explored to determine whether these loggers could be of potential use in establishing or verifying indoor vs outdoor location for future PM studies, we found that personal light intensity measurements differed among indoor, outdoor, and in-car environments (P<0.001). Overlap between measured values implies that light intensity cannot be used to absolutely predict location; however, a sudden increase or decrease in light intensity was highly associated with participant report of location change between indoors and outdoors. This study demonstrates the utility of the pDR in identifying patterns of personal exposures to particulate matter and especially in registering the magnitude and duration of excursions in PM in relation to location and activity.     

Diesel particulate matter exposure to railroad train crews

Exposure assessments were conducted aboard diesel locomotives. Results were evaluated to determine variables that affect exposure to DPM (diesel particulate matter) and to assess use of EC (elemental carbon) and OC (organic carbon) as surrogates for DPM. National Institute for Occupational Safety and Health Method 5040 was used for collection and analysis of samples in locomotives and in nonrailroad settings. The level of EC, but not OC, in locomotives was found to be significantly affected by position of exhaust stacks and windows. EC ranged from < 1 to 45 micrograms/m3 with a geometric mean (GM) of 3.7 micrograms/m3 and OC ranged from 4 to 4570 micrograms/m3 with a GM of 36.3 micrograms/m3. Background measurements of EC ranged from < 1 to 8 micrograms/m3 and OC levels were 4 to 84 micrograms/m3. This study confirms that train crew exposure to DPM is much lower than exposures for miners, is comparable to background urban exposures, and is lower than but comparable to exposures for truck drivers. It also indicates that EC levels are highly predictive of diesel exhaust exposure whereas OC levels are not, and that open windows and exhaust stack(s) in front of the locomotive cab have a significant effect on EC.     

妊娠期PM_(2.5)暴露与新生儿低出生体重的meta分析

目的定量分析和评价妊娠期PM_(2.5)暴露对新生儿低出生体重的影响。方法通过计算机联机检索国内外文献数据库,采用meta分析对妊娠期PM_(2.5)暴露与新生儿低出生体重关系的研究进行整合分析。经异质性检验后选择合适的效应模型进行统计量的计算合并,同时检验结果的稳健性及是否存在发表偏倚。结果最终筛选出16篇文献,meta分析结果显示,整个妊娠期PM_(2.5)暴露浓度每升高10μg/m~3,新生儿发生低出生体重的风险增加9.53%(95%CI:3.92%~14.84%);妊娠早、中、后期PM_(2.5)暴露浓度每升高10μg/m~3,新生儿发生低出生体重的风险分别增加6.77%(95%CI:-4.08%~17.40%),5.83%(95%CI:-2.02%~13.98%),2.96%(95%CI:-3.05%~9.53%)。敏感性分析发现,所获得的研究结果相对稳定可靠,但在分析整个妊娠期PM_(2.5)暴露对新生儿低出生体重的影响时仍存在一定的发表偏倚。结论整个妊娠期PM_(2.5)的暴露可能增加新生儿发生低出生体重的风险。     

Estimation of ambient and non-ambient components of particulate matter exposure from a personal monitoring panel study

To provide additional insight into factors affecting exposure to airborne particulate matter and the resultant health effects, we developed a method to estimate the ambient and nonambient components of total personal exposure. The ambient (or outdoor) component of total personal exposure to particulate matter (PM) (called ambient exposure) includes exposure to the ambient PM concentration while outdoors and exposure while indoors to ambient PM that has infiltrated indoors. The nonambient component of total personal exposure to PM (called nonambient exposure) refers to exposure to PM generated by indoor sources and an individual's personal activity. We used data collected from a personal monitoring study in Vancouver, Canada to demonstrate the methodology. In this study, ambient PM(2.5) exposure was 71% of the measured ambient PM(2.5) concentration and was responsible for 44% of the measured total personal PM(2.5) exposure. Regression analysis of the pooled data sets for ambient and total exposure against outdoor concentrations yielded similar slopes (0.76 for ambient and 0.77 for total) but a higher coefficient of determination for ambient exposure (R(2)=0.62) than for total exposure (R(2)=0.072). As expected, the nonambient exposure was not related to the ambient concentration (R(2)<10(-6)). For longitudinal analyses of the relationship between measured personal exposure and ambient concentrations for individual subjects, the correlation of total personal exposure with ambient concentration yielded values of Pearson's r from 0.83 to -0.68 with an average of 0.36. The relationship was statistically significant for only five of the 16 subjects. In contrast, the correlation of the estimated ambient exposure with ambient concentration yielded values of Pearson's r from 0.92 to 0.77 with an average of 0.88; 14 were significant. An example, taken from an epidemiologic analysis using the exposure data from this paper, demonstrates the usefulness of separating total exposure into its ambient and nonambient components.     

Estimation of personal exposures to particulate matter and metals in boiler overhaul work

OBJECTIVE: We sought to develop an algorithm and estimate unmeasured exposures to particulate matter (PM) and metals in an epidemiologic study of boilermakers. METHODS: The algorithm was based on limited measurements and workers' task and time activity patterns. Half of the measurements were used to develop exposure estimates for unmeasured person days. The other half was used for method validation. RESULTS: The validation demonstrated good approximations of actual exposures with differences less than 5% for PM and vanadium (V). Average estimated exposures to PM (mg/m3) and V (microg/m3) were significantly higher for workers doing boiler repair than utility work (0.36 vs. 0.09 for PM and 5.99 vs. 0.38 for V). CONCLUSIONS: This algorithm provided reasonably accurate exposure indices for our epidemiologic study in this population. It also is likely applicable to similar exposure scenarios in other studies.     

Occupational exposure to polycyclic aromatic hydrocarbons in airborne particulate matter: validation and application of a gas chromatography-mass spectrometry analytical method

This study concerns the validation of an analytical method for the measurement of occupational exposure to trace levels of polycyclic aromatic hydrocarbons (PAHs) in airborne particulate matter (APM). Personal exposure to selected PAHs of five workers occupationally exposed to urban pollution in Rome, Italy, was evaluated. The samples were collected over 10 days evenly distributed during winter and summer of 2008. Polycyclic aromatic hydrocarbons were collected by a sampling pump and trapped in polytetrafluoroethylene filters; ultrasonic extraction was applied to extract PAH species from the matrix with toluene, and the concentrated extract was quantitatively analyzed by GC/MS. The analytical method was optimized and validated using a standard reference material of urban dust (SRM 1649a). Detection limits ranged from 0.8 ng per sample for indeno [1,2,3-cd] pyrene to 20.4 ng for sample for anthracene. Experimental results of the 50 personal samples collected showed that phenanthrene was the predominant polycyclic aromatic hydrocarbon [95% CI (32.42-41.13 ng m(-3))]; the highest benzo[a]pyrene concentration was 2.58 ng m(-3), approximately 2-fold higher than European annual target values (1 ng m(-3)). Seasonal variations of personal exposure to selected PAHs suggested higher emissions and reduced atmospheric reactivity of PAH compounds in winter. The analytical method was a suitable procedure for the determination of 13 of the 16 priority PAHs in APM personal samples and can be considered a useful tool to evaluate occupational exposure to low PAH levels.     

Occupational exposure to particulate matter in 2 Portuguese waste-sorting units

Objectives

This study intended to characterize work environment contamination by particles in 2 waste-sorting plants.

Material and Methods

Particles were measured by portable direct-reading equipment. Besides mass concentration in different sizes, data related with the number of particles concentration were also obtained.

Results

Both sorting units showed the same distribution concerning the 2 exposure metrics: particulate matter 5 (PM₅) and particulate matter 10 (PM₁₀) reached the highest levels and 0.3 μm was the fraction with a higher number of particles. Unit B showed higher (p < 0.05) levels for both exposure metrics. For instance, in unit B the PM₁₀ size is 9-fold higher than in unit A. In unit A, particulate matter values obtained in pre-sorting and in the sequential sorting cabinet were higher without ventilation working.

Conclusions

Workers from both waste-sorting plants are exposed to particles. Particle counting provided additional information that is of extreme value for analyzing the health effects of particles since higher values of particles concentration were obtained in the smallest fraction.