Respiratory responses to exercise in Divers at 0.4 MPa ambient air pressure

Object: This study was carried out to evaluate changes in the breathing pattern of divers during exercise at an elevated ambient air pressure equivalent to a depth of 30 m of seawater. Methods: A total of 22 healthy male subjects performed graded bicycle exercise in a dry hyperbaric chamber up to a maximum of 3.5 W kg⁻¹ body weight at normal (0.1 MPa) and at elevated ambient air pressure (0.4 MPa). The exercise ventilation (VE), tidal volume (VT), breathing frequency (BF), oxygen uptake (VO₂), carbon dioxide elimination (VCO₂), and heart rate (HR) were measured. Perceived dyspnea was assessed by Borg scale ratings. Results: Comparison of respiratory indices between conditions (0.1 versus 0.4 MPa) revealed a significant reduction in VE, VT, BF, and HR during exercise at 0.4 MPa. VO₂ and VCO₂ did not differ significantly between conditions. Likewise, no significant difference between conditions emerged in perceived dyspnea. Conclusion: Ventilation is significantly impaired during heavy bicycle exercise at 0.4 MPa. This is obviously not apparent with regard to subjective perception of dyspnea. Received: 12 December 1997 / Accepted: 20 April 1998     

Health effects of particles in ambient air

A summary of a critical review by a working group of the German commission on Air Pollution Prevention of VDI and DIN of the actual data on exposure and health effects (excluding cancer) of fine particulate air pollution is presented. EXPOSURE: Typical ambient particle concentrations for PM10 (PM2.5) in Germany are in the range of 10-45 (10-30) microg/m3 as annual mean and 50-200 (40-150) microg/m3 as maximum daily mean. The ratio of PM2.5/PM10 generally amounts between 0.7 and 0.9. HEALTH EFFECTS: During the past 10 years many new epidemiological and toxicological studies on health effects of particulate matter (PM) have been published. In summary, long-term exposure against PM for years or decades is associated with elevated total, cardiovascular, and infant mortality. With respect to morbidity, respiratory symptoms, lung growth, and function of the immune system are affected. Short-term studies show consistant associations of exposure to daily concentrations of PM with mortality and morbidity on the same day or the subsequent days. Patients with asthma, COPD, pneumonia, and other respiratory diseases as well as patients with cardio-vascular diseases and diabetes are especially affected. The strongest associations are found for PM2.5 followed by PM10, with no indication of a threshold value for the health effects. The data base for ultra fine particles is too small for final conclusions. The available toxicological data support the epidemiological findings and give hints as to the mechanisms of the effects. CONCLUSION: The working group concludes that a further reduction of the limit values proposed for 2005 will substantially reduce health risks due to particulate air pollution. Because of the strong correlation of PM10 with PM2.5 at most German sites there is no specific need for limit values of PM2.5 for Germany in addition to those of PM10.     

Cardiovascular effects of nickel in ambient air

BACKGROUND: Fine particulate matter (FPM) in ambient air causes premature mortality due to cardiac disease in susceptible populations. OBJECTIVE: Our objective in this study was to determine the most influential FPM components. METHODS: A mouse model of atherosclerosis (ApoE-/-) was exposed to either filtered air or concentrated FPM (CAPs) in Tuxedo, New York (85 microg/m3 average, 6 hr/day, 5 days/week, for 6 months), and the FPM elemental composition was determined for each day. We also examined associations between PM components and mortality for two population studies: National Mortality and Morbidity Air Pollution Study (NMMAPS) and Hong Kong. RESULTS: For the CAPs-exposed mice, the average of nickel was 43 ng/m3, but on 14 days, there were Ni peaks at approximately 175 ng/m3 and unusually low FPM and vanadium. For those days, back-trajectory analyses identified a remote Ni point source. Electrocardiographic measurements on CAPs-exposed and sham-exposed mice showed Ni to be significantly associated with acute changes in heart rate and its variability. In NMMAPS, daily mortality rates in the 60 cities with recent speciation data were significantly associated with average Ni and V, but not with other measured species. Also, the Hong Kong sulfur intervention produced sharp drops in sulfur dioxide, Ni, and V, but not other components, corresponding to the intervention-related reduction in cardiovascular and pulmonary mortality. CONCLUSIONS: Known biological mechanisms cannot account for the significant associations between Ni with the acute cardiac function changes in the mice or with cardiovascular mortality in people at low ambient air concentrations; therefore, further research is needed.     

The concentration, dry deposition, composition study of ambient air particulate and metallic pollutants at a traffic sampling site

Aerosol samples were collected by total suspended particulate (TSP) and dry deposition plate (downward, upward) from August to November in 2003 in central Taiwan. The particulate metallic elements (Fe, Pb, Zn, Cu, Mg and Mn) were also measured in this study during the summer and autumn periods of 2003. The results obtained in this study indicated that the ambient air particulate mass concentrations in the daytime period (averaged 975.4 microg/m3) were higher than the night-time period (averaged 542.1 microg/m3). And the downward dry deposition fluxes (averaged 58.12 microg/m2-sec) were about 2.2 times that of upward dry deposition fluxes (averaged 26.37 microg/m2-sec) in the daytime period. Furthermore, the average downward dry deposition fluxes (averaged 26.54 microg/m2-sec) were also about 2.3 times that of upward dry deposition fluxes (averaged 11.52 microg/m2-sec) in the night-time period. Moreover, the average downward dry deposition fluxes are greater than the upward dry deposition fluxes for all the heavy metals in either daytime or night-time period. In addition, the deposition velocity for mass, metallic elements (Fe, Pb, Zn, Cu, Mg and Mn) during daytime and night-time period were also calculated. In addition, the average TSP composition (mg/g) in the daytime period of the metallic elements (Fe, Pb, Zn, Cu, Mg and Mn) is 1.73, 0.26, 1.16, 0.28, 0.43 and 0.12 mg/g, respectively. And the average TSP composition in the night-time period of the metallic elements (Fe, Pb, Zn, Cu, Mg and Mn) is 3.02, 0.33, 1.57, 0.41, 0.58 and 0.13 mg/g, respectively at traffic sampling site of central Taiwan.     

短期空气污染与苏州儿童青少年血压的关联性

明确短期空气污染与儿童青少年血压的关系,为采取健康干预措施和加强学校卫生管理工作提供科学依据.方法 采用整群抽样的方法,在苏州城区、郊县共监测12所中小学校2 925名儿童青少年.采用《学生健康状况及影响因素调查表》进行问卷调查及体格检查,同时收集同时期大气污染物日监测资料.结果 调整相关危险因素后,空气污染与儿童青少年血压升高存在正相关,PM 10,PM2.5,SO2,NO2每增加10 μg/m3,OR值(95%CI)分别为1.09(1.02~1.16)、1.12(1.03~1.22)、1.59(1.22~ 2.07)和1.09(1.02~ 1.16);CO每增加0.1 mg/m3,OR值(95%CI)=1.11(1.02~ 1.19);AQI每增加10个单位,OR值(95%CI)=1.09(1.02~ 1.17).结论 空气污染是儿童青少年血压升高的危险因素,PM10,PM2.5,SO2,CO,NO2及AQI指数与动脉血压的升高有不同程度的正相关.     

Respiratory health and indoor air pollution at high elevation

In this research, the authors sought to provide experimental data on indoor air quality, and the resulting respiratory impact, for a high-elevation (4550 m), rural community in Ladakh, India. This community is of interest because the primarily nomadic residents burn biomass inside the home for heating and cooking. The concentrations of particulate matter (PM), endotoxin, and carbon monoxide were determined for 6 homes. Lung function data and induced sputum samples were collected for 9 female test-home subjects. In addition, lung function data were collected for 84 additional Ladakhi highlanders at this location. Sputum from 3 visiting scientists (sojourners) was collected and analyzed as well. The average PM concentration ranged from 2 mg/m3 to 7 mg/m3, with 85% of the sampled PM sized as respirable. The average endotoxin concentration ranged from 2.4 ng/m3 to 19 ng/m3, and average carbon monoxide levels ranged from 50 ppm to 120 ppm. Lung function values for the highlander population and the test-home subjects were equal to or greater than predicted, despite the highlanders' significant exposure to indoor pollutants. An induced sputum analysis revealed a significantly greater total inflammatory cell count (M +/- SD, 10(5) cell/mg) in the Ladakhi natives than in the sojourners (107.5 +/- 75.2 vs 7.1 +/- 8.1, p < .01). Although the high levels of indoor pollutants did not correlate with significant decrements in lung function, the induced sputum analysis revealed marked airway inflammation dominated by macrophages and neutrophils. It appears that augmented lung mechanics of this high-altitude population are adaptive to reduce the work of breathing; thus, decrements in lung function go undetected because the true predicted values are greater than expected.     

Exposure to ambient air pollution and prenatal and early childhood health effects

Over the last years, concern for the possible influence of exposure to air pollutants in children during gestation or the first years of life has grown; exposure levels which may be reached nowadays in our dwellings and in our streets. In the present study evidence over the possible impact of ambient air pollution on the foetus and the infants (i.e.: less than 1 year) published during the last decade, 1994–2003, are revised. Studies on infant mortality and exposure to particles show an outstanding consistence in the magnitude of the effects, despite the different designs used. As a whole, data show that an increase in 10 g/m³of particle concentration (measured as PM₁₀) is associated with to about 5% increase in post-neonatal mortality for all causes and around 22% for post-neonatal mortality for respiratory diseases. Regarding damage in foetal health, although results are not always consistent, most studies show associations with exposure to air pollution during pregnancy. However, the precise mechanisms of action of air pollutants on adverse reproductive results are still unknown, so is the period of exposure most relevant during pregnancy and the specific pollutant which may represent a higher risk. Follow-up studies evaluating personal exposure to different air pollutants are required, allowing for the adequate evaluation of the impact of each pollutant in different periods of pregnancy, as well as providing hypotheses on their possible mechanisms of action.     

Respiratory effects of air pollutants among asthmatics in central Taiwan

The authors investigated the relationship between respiratory effects and air pollutants among asthmatics in central Taiwan. A total of 12,926 subjects were selected from 8 junior high schools. Data about monthly hospital admissions for respiratory illnesses were collected over a period of 1 yr from the National Insurance Bureau. Data included how frequently subjects purchased medication and the respiratory symptoms recorded by clinic and hospital personnel. Pulmonary function tests were administered to 20% of the total study population, which was selected randomly. Data about monthly levels of air pollutants (i.e., particulate matter 10 pm and less [PM10], ozone [O3], sulfur dioxide [SO2], and nitrogen dioxide [NO2]) were provided by Taiwan's Environmental Protection Agency. The prevalence rates of asthma were correlated significantly with NO2 (r = .63) and 03 (r = .51) concentrations. Levels of NO2 and PM10 were correlated significantly with monthly hospital admissions. Forced vital capacity, forced expiratory volume in 1 sec, and peak expiratory flow for asthmatics in central Taiwan were 6-11% lower than normal predicted values for the general Taiwanese student population, adjusted for age, height, and weight. In conclusion, the increased risk of asthma and the frequency of monthly hospital admissions among asthmatics may be correlated positively with pollution levels-especially NO2 and PM10. air pollutants, asthma, mon     

Personal and ambient air pollution is associated with increased exhaled nitric oxide in children with asthma

BACKGROUND: Research has shown associations between pediatric asthma outcomes and airborne particulate matter (PM). The importance of particle components remains to be determined. METHODS: We followed a panel of 45 schoolchildren with persistent asthma living in Southern California. Subjects were monitored over 10 days with offline fractional exhaled nitric oxide (FeNO), a biomarker of airway inflammation. Personal active sampler exposures included continuous particulate matter < 2.5 microm in aerodynamic diameter (PM2.5), 24-hr PM2.5 elemental and organic carbon (EC, OC), and 24-hr nitrogen dioxide. Ambient exposures included PM2.5, PM2.5 EC and OC, and NO2. Data were analyzed with mixed models controlling for personal temperature, humidity and 10-day period. RESULTS: The strongest positive associations were between FeNO and 2-day average pollutant concentrations. Per interquartile range pollutant increase, these were: for 24 microg/m3 personal PM2.5, 1.1 ppb FeNO [95% confidence interval (CI), 0.1-1.9]; for 0.6 microg/m3 personal EC, 0.7 ppb FeNO (95% CI, 0.3-1.1); for 17 ppb personal NO2, 1.6 ppb FeNO (95% CI, 0.4-2.8). Larger associations were found for ambient EC and smaller associations for ambient NO2. Ambient PM2.5 and personal and ambient OC were significant only in subjects taking inhaled corticosteroids (ICS) alone. Subjects taking both ICS and antileukotrienes showed no significant associations. Distributed lag models showed personal PM2.5 in the preceding 5 hr was associated with FeNO. In two-pollutant models, the most robust associations were for personal and ambient EC and NO2, and for personal but not ambient PM2.5. CONCLUSION: PM associations with airway inflammation in asthmatics may be missed using ambient particle mass, which may not sufficiently represent causal pollutant components from fossil fuel combustion.     

Prevalence of nickel sensitization and urinary nickel content of children are increased by nickel in ambient air

In a cross-sectional study performed in 2000, an unexpected positive association between nickel (Ni) in ambient air, urinary Ni content and the prevalence of Ni sensitization in a subgroup of 6-yr-old children living near a steel mill was observed. Between 2005 and 2006, in a different and larger study population, we examined if Ni from ambient air or urinary Ni concentration was related to Ni sensitization in children living next to Ni-emitting steel mills.We studied 749 school beginners living in four Ni-polluted industrial areas of North Rhine-Westphalia, Germany. We assessed Ni in ambient air, Ni in urine from children and mothers, and Ni in tap water, conducted patch tests in children (including the NiSO₄-dilution test) and collected questionnaire data. Statistics were done by linear and logistic regression analyses, adjusted for covariates.At increased Ni concentration in ambient air (unit of increase: 10 ng/m³), urinary Ni concentrations rose in both mothers (9.1%; 95% CI: 6.8–11.4%) and children (2.4%; 95% CI: 0.4–4.4%). The prevalence of Ni sensitization in children was associated with increased Ni from ambient air (unit of increase: 18 ng/m³; odds ratio 1.28; 95% CI: 1.25–1.32) and urinary Ni concentration (unit of increase: 7.1 μg/L; odds ratio 2.4; 95% CI: 1.20–4.48). Ni in ambient air of areas with Ni-emitting factories contributes to internal Ni exposure in residents via inhalation and, furthermore, is a risk factor for the development of Ni sensitization in children.     

Respiratory health effects associated with ambient sulfates and ozone in two rural Canadian communities

A cross-sectional epidemiological study investigating the respiratory health of children in two Canadian communities was conducted in 1983-1984 in Tillsonburg, Ontario, located in a region of moderately elevated concentrations of transported air pollutants, and in Portage la Prairie, Manitoba, situated in a low pollution area. There were no significant local sources of industrial emissions in either community. Seven hundred and thirty-five children aged 7-12 were studied in the first town and 895 in the second. Respiratory health was assessed by the measurement of the forced vital capacity (FVC) and forced expiratory volume in 1 sec (FEV1.0) of each child, and by evaluation of the child's respiratory symptoms and illnesses using a parent-completed questionnaire. Sulfur dioxide (SO2), sulfate, and particulate nitrate levels were significantly higher in Tillsonburg than in Portage la Prairie (P less than 0.05), but nitrogen dioxide (NO2) and inhalable particles (PM10) differed little between the communities. Historical data in the vicinity of Tillsonburg indicated that average annual levels of sulfates, total nitrates, and ozone (O3) did not vary markedly in the 9-year period preceding the study. The results show that Tillsonburg children had statistically significant (P less than 0.001) lower levels of 2% for FVC and 1.7% for FEV1.0 as compared with children in Portage la Prairie. These differences could not be explained by parental smoking or education, the use of gas cooking or wood heating fuels, pollution levels on the day of testing, or differences in age, sex, height, or weight. The differences persisted when children with cough with phlegm, asthma, wheeze, inhalant allergies, or hospitalization before age 2 for a chest illness were excluded from analysis. With the exception of inhalant allergies, which occurred more frequently in Tillsonburg children, the prevalence of chronic respiratory symptoms and illnesses was similar in the two communities.     

Combined effects of formaldehyde and increased barometric pressure in animals

A study was performed on white rats of the physiological, biochemical, haematological and pathomorphological indices in separate and combined actions of formaldehyde (FA) (60.0 +/- 12.7 mg/m3 in one-time exposition and 7.2 +/- 1.2 mg/m3 in a 30-day long experiment) with a concomitant increased barometric pressure (IBP) characteristic of deep coal mines (111 and 123 kPa corresponding to 1000 and 2000 m deep mines respectively). It was established that, at 123 kPa, lipoid peroxide oxidation process was stimulated in combination with microcirculatory disorders, growing FA concentration in the serum and pulmanary tissues. The shifts were still more vivid at growing IBP.     

Concentrations of nano and related ambient air pollutants at a traffic sampling site

A micro-orifice uniform deposit impactor (MOUDI) and a nano-MOUDI were used to measure the atmospheric coarse (PM2.5 -10), fine (PM2.5), ultrafine (PM0.056-1) and nano (<0.056 microm) particle concentrations and size distributions at a traffic sampling site in winter in central Taiwan, from November 2004 to January 2005. Concentrations of metallic elements (Fe, Mg, Cr, Zn, Pb, Cu) and major ion (SO4(2-), NO3(-), NH4(+)) in particles of various sizes (nano, ultrafine, fine and coarse) were measured. Ambient air particulates generally exhibited a bimodal size distribution in the range 0.056-10 microm. The results show that the concentrations followed the order, Fe>Mg>Cr>Zn>Pb> Cu in PM10, fine, ultrafine and nano-sized particles. Moreover, the data showed that the average metallic elements Fe and Zn have similar concentration distributions: the concentration decreased as the particle size fell in the nano size range.     

Long-term effects of ambient air pollution on lung function: a review

Lung function is an important measure of respiratory health and a predictor of cardiorespiratory morbidity and mortality. Over the past 2 decades, more than 50 publications have investigated long-term effects of ambient air pollution on lung function with most finding adverse effects. Several studies have also suggested effects from traffic-related air pollution. There is strong support for air pollution effects on the development of lung function in children and adolescents. It remains unclear whether subjects with slower development of lung function compensate by prolonging the growth phase, or whether they end their development at a lower plateau, thus entering the decline phase with a reduced lung function. In adults, the evidence for long-term air pollution effects is mostly based on cross-sectional comparisons. One recent longitudinal study observed that decreasing pollution attenuated the decline of lung function in adults. Earlier inconclusive cohort studies were based on limited data. There is great diversity in study designs, markers of air pollution, approaches to the measurement of exposure, and choices in lung function measures. These limit the comparability of studies and impede quantitative summaries. New studies should use individual-level exposure assessment to clarify the role of traffic and to preclude potential community-level confounding. Further research is needed on the relevance of specific pollution sources, particularly with regard to susceptible populations and relevant exposure periods throughout life.     

Health effects of ambient air pollution – recent research development and contemporary methodological challenges

Exposure to high levels of air pollution can cause a variety of adverse health outcomes. Air quality in developed countries has been generally improved over the last three decades. However, many recent epidemiological studies have consistently shown positive associations between low-level exposure to air pollution and health outcomes. Thus, adverse health effects of air pollution, even at relatively low levels, remain a public concern. This paper aims to provide an overview of recent research development and contemporary methodological challenges in this field and to identify future research directions for air pollution epidemiological studies.     

Bronchomotor response to cold air or helium-oxygen at normal and high ambient pressures

Effects of inhalation of cold air or helium-oxygen mixture on lung resistance (RL) were studied in anesthetized and tracheotomized rabbits under normal ambient pressure and in human volunteers under normo- and hyperbaric conditions. In artificially ventilated rabbits, an increase in RL occurred when the tracheal temperature fell to 10 degrees C. This effect was more than double with helium breathing compared to air, despite a lower respiratory heat loss by convection (Hc) with helium. In 3 normal humans, inhalation of cold air (mouth temperature = 8 degrees C) at sea level had no effect on RL value. However, with a helium-nitrogen-oxygen mixture, a weak but significant increase in RL due to cold gas breathing was measured in 1 subject at 2 ATA and in 2 individuals at 3.5 ATA. The density of inhaled gas mixture (air or He-N2-O2) was near the same in the three circumstances (1, 2, and 3.5 ATA) but Hc value increased with helium. At 8 ATA a 30-55% increase in RL occurred in the 3 divers during inhalation of cold gas (Hc was multiplied by 6 compared to air at sea level) and at 25 ATA the cold-induced bronchospasm ranged between 38 and 95% (Hc multiplied by 27). Thus, in rabbits and humans helium breathing enhanced the cold-induced increase in RL at normal or elevated ambient pressure, and this effect was interpreted as resulting from different mechanisms in the two circumstances.