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At least 343 records · Page 19Linked to original sources
PubMed2003

A physiological and morphological study on the injury caused by exposure to the air pollutant, peroxyacetyl nitrate (PAN), based on the quantitative assessment of the injury.

A method for the numerical assessment of the foliar injury caused by the photochemical oxidant, peroxyacetyl nitrate (PAN), was devised, using three injury indices: fresh weight (FW) loss, decreased photosynthetic pigment content, and increased ion leakage, which can be measured using the same leaves. The injury indices clearly indicated a larger number of PAN-sensitive leaves and a more severe level of injury in the PAN-sensitive variety of Petunia hybrida, White Champion (WHITE), compared to the PAN-tolerant variety, Blue Champion (BLUE). FW and photosynthetic pigment content decreased correlatively in both varieties, but ion leakage increased only in WHITE. Morphological observations revealed that ion leakage started concurrently with the start of plasmolysis-like symptoms at the mesophyll cells of injured WHITE leaves, whereas FW loss corresponded to the shrinkage of cells without loss of their round shape in BLUE leaves. PAN injuries measured by the injury indices were markedly increased in the presence of light, and the morphological changes following PAN exposure were similar to those caused by the superoxide-generating chemical, paraquat. The results suggested that PAN injuries indicated by the three injury indices are all light-dependent, but are caused through several independent mechanisms.

Air Pollutants↗
PubMedDate not supplied

Automotive exhaust and mouse activity: relationships between pollutant concentrations and decreases in wheel running.

Groups of male and female mice inhaled either clean air, 100 ppm carbon monoxide, or light-irradiated and nonirradiated automotive exhaust containing nominally 25, 50, 75, or 100 ppm carbon monoxide in three tests with exposure lasting from 4 to 7 days. Exhaust from a factory or lean-tuned engine in the first and third tests reversibly suppressed activity wheel running during exposure in mice of both sexes by as much as 78.3 and 83.1%, respectively. Light-irradiated exhaust suppressed running more than nonirradiated exhaust. For the second test, when the engine was tuned to be low in pollutants other than carbon monoxide, exhaust did not suppress running. Exposure to carbon monoxide alone only slightly decreased running in male mice, but increased running in female mice.

Air Pollutants↗
PubMedDate not supplied

Human exposure to pollutants in Poland.

Serious environmental problems caused by decades of mismanagement of Poland's natural resources have been brought to light in recent years. All environmental media--air, water, food, and soil--have been burdened with toxic chemicals. Some environmental problems are so severe that the sources of pollution and the mitigation techniques needed are obvious, requiring no further research, but rather common sense, monies, and determination to implement the necessary controls and mitigation procedures. This paper will not address these obvious cases. Rather it will address that spectrum of environmental problems which requires a better understanding of public health risk in order to develop effective risk management strategies. Because these problems are numerous and monies limited, policy makers will need to set priorities both for research projects and control options. Using environmental concentration data presently available from Poland (especially for air), the paper will estimate human exposures, will point out research and monitoring needs, and hopefully, will lend credence to the concept that environmental policies and risk reduction strategies will be most effective if the Total Human Exposure Concept is used as the guiding scientific principle in risk assessment and management programs.

Air Pollutants↗
PubMed2000

Combined effects of aerobiological pollutants, chemical pollutants and meteorological conditions on asthma admissions and A & E attendances in Derbyshire UK, 1993-96.

BACKGROUND: The effect of outdoor aeroallergen exposure in asthma may be enhanced by air pollutants, including ozone, nitrogen dioxide and particulates, and by certain weather conditions. It is not yet established whether these interactions are important in determining asthma morbidity at the population level. OBJECTIVE: We have investigated the joint effects of aeroallergens, rainfall, thunderstorms and outdoor air pollutants on daily asthma admissions and Accident and Emergency (A & E) attendance using routinely collected data between 1993 and 1996 from Derby in central England. METHODS: Daily counts during the aeroallergen season of grass and birch pollen, basidiospores, Didymella, Alternaria and Cladosporium, maximum 1 hour ozone and nitrogen dioxide and daily average black smoke measurements, all made in the vicinity of the city centre, were categorized in tertiles. Rainfall was classified as dry, light (</= 2 mm) or heavy (> 2 mm). The modifying effect of outdoor pollutant levels, and rainfall or the occurrence of a thunderstorm, upon the effects of individual aeroallergens on asthma admissions and A & E attendance were investigated by fitting appropriate interactions in log linear autoregression models with adjustment for potential confounders. RESULTS: We found a significant interaction between the effects of grass pollen and weather conditions upon A & E attendance, such that the increase with grass pollen count was most marked on days of light rainfall (adjusted rate ratio for >/= 50 vs < 10 grains/m3 at lag 2 days = 2.1, 95% CI 1.4, 3.3). Asthma admissions increased with Cladosporium count. We found no statistically significant interactions between effects of any individual aeroallergen and outdoor air pollutant upon either measure of asthma morbidity. CONCLUSIONS: Rainfall and thunderstorms are important effect modifiers in the relation between grass pollen and measures of acute asthma morbidity. Interactions between ambient levels of aeroallergens and chemical pollutants in the Derby area do not play a major role in determining asthma admissions and A & E attendance.

Air Microbiology↗
PubMedDate not supplied

Inflammatory cells and ferruginous bodies in bronchoalveolar lavage in urban dogs.

OBJECTIVE: To investigate whether high levels of atmospheric pollution modify the inflammatory cell count of the canine lung and to detect the presence of ferruginous bodies (FB) in the respiratory system. STUDY DESIGN: Bronchoalveolar lavage (BAL) was performed on dogs from four different areas of Mexico City and a rural area. With the BAL fluid recovered, total and differential cell counts were made, and ferruginous bodies were isolated by sodium hypochlorite digestion. They were counted by light microscopy and evaluated as a marker of exposure to particulate pollutants. RESULTS: There was no significant difference in the total cell count or in the macrophage number between the five groups. The neutrophil count was statistically higher in dogs from the southwest area as compared to the northeast and rural areas (P < .05). The lymphocyte count was significantly greater in the southwest, also. The northeast part of the city showed the highest number of FB in BAL fluids. CONCLUSION: The most polluted areas, in terms of particulate matter, were the northeast and the northwest; those are the locations of heavy industry. In contrast, in the southwest, where more inflammation was seen, the highest levels of ozone were registered during the year.

Animals↗
PubMed2006

Comparison of EC and BC and evaluation of dust aerosol contribution to light absorption in Xi'an, China.

The concentrations of EC, BC and dust aerosols were determined for atmospheric samples collected from an observation station in Xi'an, China. The results show that the averaged correlation coefficient between EC and BC was founded to be 0.72 with 0.81 (n = 49) in autumn, 0.70 (n = 112) in winter and 0.69 (n = 57) in spring, respectively. Absorption coefficients of dust aerosol were estimated to be 2.7 m(2) g(-1) in autumn and 4.4 m(2) g(-1) in winter. The comparison of absorption coefficients of dust aerosol with those of BC implies that BC is the principal light-absorbing aerosol over Xi'an atmosphere. By combining thermal analysis of elemental carbon and dust contents in the aerosol samples, however, the fraction of dust absorption to total light absorption is estimated to be 19% in autumn and 31% in winter, respectively.

Aerosols↗
PubMed2000

Colorimetric determination of formaldehyde in air using a hanging drop of chromotropic acid.

A simple and sensitive method to determine parts per billion (ppb) of atmospheric formaldehyde in situ, using chromotropic acid, is described. A colorimetric sensor, coupled to a droplet of 15.5 microL chromotropic acid, was constructed and used to sample and quantify formaldehyde. The sensor was set up with two optical fibers, a light emitting diode (LED) and two photodiodes. The reference and transmitted light were measured by a photodetection arrangement that converts the signals into units of absorbance. Air was sampled around the chromotropic acid droplet. A purple product was formed and measured after the sampling terminated (typically 7 min). The response is proportional to the sampling period, analyte concentration and sample flow rate. The detection limit is approximately 2 ppb and can be improved by using longer sampling times and/or a sampling flow rate higher than that used in this work, 200 mL min-1. The present technique affords a simple, inexpensive near real-time measurement with very little reagent consumption. The method is selective and highly sensitive. This sensor could be used either for outdoor or indoor atmospheres.

Air Pollution, Indoor↗
PubMed2003

The light transmission and distribution in an optical fiber coated with TiO2 particles.

The light delivery and distribution phenomena along the optical fiber coated with the P-25 TiO(2) particles by dipping was investigated. The surface properties (coverage, roughness and thickness) of the TiO(2) layer coated on the optical fiber were characterized by SEM micrographs. For TiO(2) layer prepared from solutions containing less than 20 wt.% of TiO(2) slurry, the thickness of layer was increased linearly with the TiO(2) slurry content in solutions. The UV light intensity transmitted along a TiO(2)-coated optical fiber decreased more rapidly than that transmitted along a non-coated fiber. Based on the experimental results, the light intensity distribution around a coated optical fiber was modeled to determine the optimum configuration for the design of optical fiber reactors under various operational conditions.

Air Pollution↗
PubMed1989

Ozone and ultraviolet light act as additive cocarcinogens to induce in vitro neoplastic transformation.

Ozone, a major chemical oxidant in our environment, is an environmental air pollutant with putative carcinogenic action. Using in vitro transformation, we report for the first time that ozone (6 ppm for 10 min) acts in additive fashion with ultraviolet light (4 J/m2) to produce enhanced levels of transformation in hamster embryo cells and mouse C3H/10T-1/2 cells as compared to rats induced by each of the agents alone. The results underscore the hazard of ozone as a toxic pollutant which may have putative carcinogenic effects and interact with other environmental carcinogens.

Air Pollutants↗
PubMed1990

Airways and air pollution in childhood: state of the art.

Correlations between ambient pollutants and health effects, such as observed in SIDS, may in reality be to a larger extent the result of indoor sources. These distinctions between indoor and outdoor sources, while important, do not detract from the overall conclusion that pollution affects the airway in children directly and indirectly. Much still needs to be learned about the permanence of these effects, the mechanism by which the effect is mediated, and the conditions under which some of these effects are maximal. Two approaches seem particularly suited to shed further light on these issues. First, identification of biological markers for exposure to pollutants will yield both more accurate measures of exposure to pollutants and information about health consequences. Second, newer modeling techniques promise to predict health outcomes under a variety of environmental conditions. Shumway et al., for instance, describe a promising model predicting an increase in mortality due to ambient pollutants in the Los Angeles Basin with higher levels under extremes of temperature, especially during cold spells. Time series and factor analyses may further our knowledge as well. In the near future, large cohort studies should begin to reveal the cumulative effects of air pollution on the respiratory system, especially in relation to active smoking. Finally, studies in Black children are virtually unavailable. Given their high risk for respiratory illnesses, such studies are sorely needed.

Air Pollutants↗
PubMed2006

Photodegradation of dye pollutants catalyzed by porous K3PW12O40 under visible irradiation.

Microporous solid K3PW12O40 is prepared by precipitation of phosphotungstic acid and potassium ion, followed by calcination. Using this material as photocatalyst, a series of dye pollutants, such as rhodamine B, malachite green, rhodamine 6G, fuchsin basic, and methyl violet, were efficiently degraded in the presence of H202 under visible light irradiation (lambda > 420 nm). The photocatalyst was characterized via SEM, BET surface area, FT-IR, and XRD. The photocatalyst has relative large surface area, and the Keggin structure of phosphotungstic ions is intact during the precipitation and calcination. The degradation kinetics, TOC changes, degradation products, ESR detection of active oxygen species, and the effect of radical scavengers are also investigated to clarify the degradation process and the reaction pathway. The dyes can be facilely bleached and mineralized (ca. 40% of TOC removal for RhB), and the main degradation products of RhB detected, besides CO2, are the small organic acids. They are released from the surface of the catalyst to the bulk solution during the degradation of the dye, which avoids the poisoning of photocatalyst by the intermediates. The formation of active oxygen species such as the O2-*/ HO2* and *OH are detected during the degradation of dye, and they are proposed to be responsible for the degradation of dyes. The K3PW12040 catalyst is very stable and very easily separated from the reaction system for reuse.

Catalysis↗
PubMed1999

Mortality among residents near cokeworks in Great Britain.

OBJECTIVES: To investigate whether residents near cokeworks have a higher standardised mortality than those further away, particularly from cardiovascular and respiratory causes, which may be associated with pollution from cokeworks. METHOD: Cross sectional small area study with routinely collected postcoded mortality data and small area census statistics. Populations within 7.5 km of 22 cokeworks in Great Britain, 1981-92. Expected numbers of deaths within 2 and 7.5 km of cokeworks, and in eight distance bands up to 7.5 km of cokeworks, were calculated by indirect standardisation from national rates stratified for age and sex and a small area deprivation index, and adjusted for region. Age groups examined were all ages, 1-14, 15-64, 65-74, > or = 75. Only the 1-14 and 15-44 age groups were examined for asthma mortality. RESULTS: There was a 3% (95% confidence interval (95% CI) 1% to 4%) excess of all deaths within 2 km of cokeworks, and a significant decline in mortality with distance from cokeworks. The excess of deaths within 2 km was slightly higher for females and elderly people, but excesses within 2 km and declines in risk with distance were significant for all adult age groups and both sexes. The size of the excess within 2 km was 5% (95% CI 3% to 7%) for cardiovascular causes, 6% (95% CI 3% to 9%) for ischaemic heart disease, and 2% (95% CI -2% to 6%) for respiratory deaths, with significant declines in risk with distance for all these causes. There was a non-significant 15% (95% CI -1% to 101%) excess in asthma mortality in the 15-44 age group. There were no significant excesses in mortality among children but 95% CIs were wide. Within 2 km of cokeworks, the estimated additional excess all cause mortality for all ages combined related to region and mainly to the greater deprivation of the population over national levels was 12%. CONCLUSIONS: A small excess mortality near cokeworks as found in this study is plausible in the light of current evidence about the health impact of air pollution. However, in this study the effects of pollution from cokeworks, if any, are outweighed by the effects of deprivation on weighed by the effects of deprivation on mortality near cokeworks. It is not possible to confidently exclude socioeconomic confounding or biases resulting from inexact population estimation as explanations for the excess found.

Adolescent↗
PubMed2004

An undoped, single-phase oxide photocatalyst working under visible light.

A novel photocatalyst, PbBi2Nb2O9 has been discovered that shows high activities for degradation of organic pollutants, generation of photocurrent, and water decomposition into O2 or H2, all under visible right irradiation (lambda >/= 420 nm). This is the first example of an undoped, single-phase oxide photocatalyst that shows such reactivity. Its quantum yields are much higher than those for most of the previously reported materials, especially in water decomposition to generate oxygen (29%). Since it is an oxide, there is much less concern for stability under light irradiation.

Journal Article↗
PubMed2003

Differential thermal lensing in extended samples.

We present a new scheme for a pump-probe mode-mismatched thermal lensing experiment aimed at extracting the value of low-absorbing components in the presence of a high-absorbing background. The method allows for the use of large path-length samples. Changes in the background absorption of a column of ethanol of 20 cm of 1% and a pollutant concentration detection limit of 0.04 ppm are obtained when using a pump light power of 34 mW.

Differential Thermal Analysis↗