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PubMed2002

Induction of discolored wood in Scots pine (Pinus sylvestris).

Induction of discolored wood in Scots pine (Pinus sylvestris L.) trees by treatment with ethylene, carbon dioxide, nitrogen (hypoxia) or wounding from early April to late September was investigated. All treatments induced formation of discolored wood upward and downward from the drill hole. The amount of discolored wood formed above the drill hole depended on the treatment in the following order: ethylene > carbon dioxide = nitrogen > wounding; and below the drill hole in the order: ethylene > carbon dioxide = nitrogen = wounding. Based on chemical analyses (HPLC/UV, GS/MS, LC/MS and 1H-NMR), discolored wood induced by wounding or treatment with ethylene or carbon dioxide showed compositional similarities to natural heartwood, whereas discolored wood induced by nitrogen treatment showed fewer similarities to natural heartwood. The results suggest that ethylene is an important factor controlling heartwood formation, although wounding and internal concentrations of carbon dioxide may also play a role.

Carbon Dioxide↗
PubMed2001

Characteristics of urban ozone level in Hong Kong.

The long term trend of ozone level in Hong Kong has been investigated. One of the characteristics of ozone level in Hong Kong is the existence of autumn maximum and summer minimum. Observations of the diurnal variation of ozone level have been made in different area categories. There are early morning peak and afternoon peak occurred in the diurnal variation, which are different from some metropolitans where only an afternoon peak is observed. A negative correlation coefficient was found between monthly ozone level with nitric oxide level. On the contrary, there is a positive correlation between ozone and nitrogen dioxide. The positive correlation coefficient between nitric oxide and nitrogen dioxide shows that the total amount of nitric oxide emitted from a series of moving and fixed sources greatly exceeded the stoichiometric amount of ozone formed from chemical reactions of precursors and long distance transportation.

Air Pollutants↗
PubMed2002

Degradation of the adsorbent Tenax TA by nitrogen oxides, ozone, hydrogen peroxide, OH radical, and limonene oxidation products.

The degradation of the adsorbent Tenax TA was studied qualitatively by sampling oxidants common in indoor air followed by thermal desorption and gas chromatography. A total of 25 degradation products were identified. Several degradation products not reported previously were identified: 9 for nitrogen dioxide; 11 for ozone; 2 for hydrogen peroxide; 12 for hydroxyl radical; 1 for ozone-limonene mixtures, but none for nitrogen oxide. Whereas ozone shows a complex degradation of the adsorbent, hydrogen peroxide and limonene--ozone mixtures show few products. Nitrogen dioxide and the hydroxyl radical behave almost identically and produce 2,6-diphenyl-p-benzoquinone as the major degradation product. Reactant specific degradation products were identified for ozone (11) and nitrogen dioxide (1).

Air Pollutants↗
PubMed2004

Adsorption properties of gases on mesoporous chromium silicate.

The properties of nitrogen, carbon dioxide, and nitrogen dioxide adsorption onto mesoporous chromium silicates were studied by measurements of both the adsorption isotherms and the IR spectra. The pore sizes of two types of chromium silicates, Cr-FSM-16 (Si/Cr=170 (Cr-FSM-16 [170]) and 390 (Cr-FSM-16 [390])), which contain different amount of Cr, were 2.75 nm. BET surface areas of Cr-FSM-16 were 590 m2/g and they were smaller than that onto FSM-16. The initial heat of adsorption of nitrogen onto Cr-FSM-16 was higher than that onto FSM-16. But the initial heat of adsorption of carbon dioxide onto Cr-FSM-16 was smaller than that onto FSM-16. These results indicated that Cr in Cr-FSM-16 decreased adsorption interaction with carbon dioxide. When nitrogen dioxide was adsorbed on FSM-16 and Cr-FSM-16 at 303 K under no light, an absorption band of nitrogen monoxide adsorbed was measured by IR spectroscopy. This decomposition of nitrogen dioxide by FSM-16 and Cr-FSM-16 was caused by SiOH and Cr, respectively.

Adsorption↗
PubMedDate not supplied

Air quality monitoring during indoor Monster Truck and car demolition shows.

This article describes the results of air quality monitoring in an indoor ice skating rink during three Monster Truck and car demolition exhibitions, and the public health study that was carried out. The exposure of the people present to carbon monoxide and nitrogen dioxide was continuously monitored in order to determine the time-weighted average concentrations and the maximum peaks. Nitrogen dioxide concentrations were generally under the limit of detection of the device (0.5 ppm). However, carbon monoxide levels exceeded standards for workers. Maximum time-weighted average concentrations during the exhibitions were 100 parts per million with several peaks exceeding 200 parts per million (maximum value: 1600 parts per million). Recommendations were made and during a subsequent event, the carbon monoxide concentrations were reduced to protect health. Indoor exhibitions of motorized vehicles generate significant amounts of combustion gases, which can be a health hazard. There must be sufficient ventilation and the carbon monoxide and nitrogen dioxide concentrations must be monitored. In addition, the motors of the most polluting vehicles should be adjusted before the events in order to limit the emission of combustion products. If these steps are not met, the events should be held outdoors.

Air Pollution, Indoor↗
PubMed1990

Oxidant effects on rat and human lung proteinase inhibitors.

This project tested the hypothesis that inhaled oxidants could cause lung damage by inactivating the proteinase inhibitors that normally protect the lung from proteolysis. Rat alpha-1-proteinase inhibitor (alpha 1-PI)2 was purified from blood plasma, and antibodies to this inhibitor were prepared. The activity of alpha 1-PI in lung lavage fluids from rats was measured by elastase inhibition, and the immunological concentration of alpha 1-PI was quantified in an enzyme-linked immunoassay. The ratio of the amount of active alpha 1-PI relative to its immunological concentration was examined as a measure of the inhibitor's functional activity. This ratio and the ratio of the immunological concentration of alpha 1-PI to the total protein concentration were determined in lung lavage fluids from rats exposed to air, 10 parts per million (ppm) nitrogen dioxide, and diesel emissions (3.5 mg/m3 particulates) for 12, 18, and 24 months. Only diesel exposures resulted in a statistically significant reduction in the functional activity of alpha 1-PI of 30 percent (p less than 0.05). Similar studies were performed on rats exposed to nitrogen dioxide (0.5 ppm background with peaks of 1.5 ppm) and ozone (0.06 ppm background with peaks of 0.25 ppm) for 12 and 18 months. No statistically significant effects were observed in the functional activity of alpha 1-PI or its immunological concentration. In other protocols, rats were acutely exposed to 0.8 ppm or 1.2 ppm ozone for two, four, or eight hours, and to 0.5 ppm or 0.8 ppm ozone in conjunction with 8 percent carbon dioxide for two or seven hours. Although these acute exposure conditions did not reduce the functional activity of alpha 1-PI, the immunological concentration of alpha 1-PI and the elastase inhibitory activity, relative to other proteins, were significantly increased in relation to the total amount of ozone inhaled. The functional activity of alpha 1-PI also was measured in the bronchoalveolar lavage fluids of human subjects exposed to nitrogen dioxide (0.05 ppm with 2 ppm peaks, or to 1.5 ppm continuously) for three hours and to ozone (0.4 ppm) for two hours during exercise. These exposures did not result in significant changes in the functional activity of alpha 1-PI or its immunological concentration.(ABSTRACT TRUNCATED AT 400 WORDS)

Air Pollutants↗
PubMed2003

A long-term study of oxides of nitrogen, sulphur dioxide, and ammonia for a port and harbor region in India.

A long-term study of oxides of nitrogen (NOx), sulphur dioxide (SO2), and ammonia (NH3) has been performed in a port and harbor region in India from January 1997 to December 2000. Meteorological data was also collected to establish the correlation with gaseous pollutants concentrations. Monthly mean concentrations of NOx were in the range of 19.5-59.0 microg/m3 and were observed to be highest during winter season. Monthly mean concentrations of SO2 were in the range of 8.6-51.3 microg/m3 and were observed to be highest during winter season. The concentrations of SO2 increased gradually from 18.8 microg/m3 in 1997 to 33.3 microg/m3 in 2000. This may be attributed to the increase in port activities and ship traffic, which had an annual growth of about 15%. Monthly mean concentrations of NH3 were in the range of 87.1-235.1 microg/m3 and the maximum concentration was observed during post-monsoon season. It may be concluded that NOx and SO2 have their maximum values during winter season while NH3 has a maximum value during post-monsoon season. Statistical analysis was carried out for air pollutant data for the period 1997-2000 and correlation between gaseous pollutants (NOx, SO2, NH3) and meteorological parameters (temperature and wind speed) was estimated. NH3 was found to be weakly correlated with NOx (0.46), strongly correlated with SO2 (0.75) and negatively correlated with wind speed (-0.60). The highest correlation (0.87) was observed between SO2 and NOx because of common sources. A strong negative correlation was found between wind speed and gaseous pollutants. The above finding is also supported by monitoring results that when the wind velocity doubled, the concentrations of pollutants decreased sharply to about a half. Regression analysis showed that relationship among NOx, SO2, wind speed, and temperature was moderate to strong while that among NH3, wind speed, and temperature was poor. Hence regression equations could be developed for predicting NOx and SO2 concentrations.

Air Movements↗
PubMed1983

Electron-spin resonance study of mainstream and sidestream cigarette smoke: nature of the free radicals in gas-phase smoke and in cigarette tar.

Radicals in the gas phase of both mainstream and sidestream cigarette smoke have been studied using electron-spin resonance ESR spin-trapping techniques with alpha-phenyl-N-tert-butyl nitrone (PBN) as the spin trap. The principal radicals we trap appear to be alkoxyl radicals. Mainstream and sidestream gas-phase smoke each have about the same concentration of radicals, about 1 X 10(16) radicals per cigarette (or 5 X 10(14) per puff). These radicals are reactive, yet they appear to be remarkably long-lived: they are still spin trapped from gas-phase smoke after more than 5 min. We propose that a steady-state concentration of reactive radicals exists in gas phase cigarette smoke. We suggest that this steady state is produced by the slow oxidation of nitric oxide (present in high concentrations in smoke and relatively unreactive) to the more reactive nitrogen dioxide, followed by the reaction of nitrogen dioxide with reactive organic molecules in smoke (such as olefins and dienes). Preliminary experiments reported here support this hypothesis. Tar from both mainstream and sidestream smoke contains persistent free radicals that exhibit broad, single-line ESR spectra with g values of 2.003. The tar radical can be extracted into tert-butylbenzene and other organic solvents, and we have applied a variety of fractionation procedures to these solutions. Most of the radicals occur in the fractions that contain the phenolic tobacco leaf pigments. Treatment of alcoholic solutions of tar with base generates a new group of radicals that appear to be semiquinone radicals derived from the oxidation of the phenolic and polyphenolic species in tar.

Chemical Phenomena↗
PubMed2001

The bactericidal effect and chemical reactions of acidified nitrite under conditions simulating the stomach.

AIMS: To examine the hypothesis of non-immune defence mechanisms based on nitrite. METHODS AND RESULTS: The acidified media (nutrient broth or citrate-phosphate buffer) under aerobic conditions with additions of physiological levels of nitrite, L-ascorbic acid, iodide and thiocyanate were used to simulate gastric juice. The bactericidal effects of acidified nitrite on Escherichia coli and lactobacilli were investigated using bacterial plate counts. Conversion of acidified nitrite to nitric oxide, nitrogen dioxide and nitrate was also studied. Nitrite significantly increased the bactericidal effects on E. coli and lactobacilli. The bactericidal effects were enhanced by thiocyanate but not by L-ascorbic acid and iodide. L-Ascorbic acid and thiocyanate, but not iodide, enhanced the decomposition of acidified nitrite in nutrient broth. Acidified nitrite was converted to both nitric oxide and nitrate, but a portion of the acidified nitrite in nutrient broth may have been converted to other unidentified nitrogen compounds. Nitrogen dioxide was not detected in any of the samples. CONCLUSION: The bactericidal effects of nitrite appeared to be primarily related to nitrous acid, and possibly to other unidentified nitrogenous metabolites, but not to nitric oxide and nitrogen dioxide. SIGNIFICANCE AND IMPACT OF THE STUDY: The potential role of nitrite as an antimicrobial substance in the stomach may be of some importance in the ecology of the gastrointestinal tract and in host physiology.

Anti-Bacterial Agents↗
PubMed2005

Impact of ambient air pollution on birth weight in Sydney, Australia.

BACKGROUND: Studies in Asia, Europe, and the Americas have provided evidence that ambient air pollution may have an adverse effect on birth weight, although results are not consistent. METHODS: Average exposure during pregnancy to five common air pollutants was estimated for births in metropolitan Sydney between 1998 and 2000. The effects of pollutant exposure in the first, second, and third trimesters of pregnancy on risk of "small for gestational age" (SGA), and of pollutant exposure during pregnancy on birth weight were examined. RESULTS: There were 138,056 singleton births in Sydney between 1998 and 2000; 9.7% of babies (13,402) were classified as SGA. Air pollution levels in Sydney were found to be quite low. In linear regression models carbon monoxide and nitrogen dioxide concentrations in the second and third trimesters had a statistically significant adverse effect on birth weight. For a 1 part per million increase in mean carbon monoxide levels a reduction of 7 (95% CI -5 to 19) to 29 (95% CI 7 to 51) grams in birth weight was estimated. For a 1 part per billion increase in mean nitrogen dioxide levels a reduction of 1 (95% CI 0 to 2) to 34 (95% CI 24 to 43) grams in birth weight was estimated. Particulate matter (diameter less than ten microns) in the second trimester had a small statistically significant adverse effect on birth weight. For a 1 microgram per cubic metre increase in mean particulate matter levels a reduction of 4 grams (95% CI 3 to 6) in birth weight was estimated. CONCLUSION: These findings of an association between carbon monoxide, nitrogen dioxide, and particulate matter, and reduction in birth weight should be corroborated by further study.

Air Pollutants↗
PubMed1995

Effect of oxidant air pollutants on the respiratory system: insights from experimental animal research.

In the present paper, we have reviewed experimental animal studies on the effects of the two most important oxidant airborne pollutants, nitrogen dioxide and ozone, on the respiratory system. The toxic effects depend on concentration and length of exposure, and are generally similar for both oxidants, with ozone operative at lower concentrations. High doses of both oxidants cause death due to lung oedema. Exposure to sublethal levels causes functional alterations such as airflow limitation and airway hyperresponsiveness to bronchoconstrictor stimuli. These effects, which are generally reversible, are associated with epithelial injury, oedema and airway and parenchymal infiltration by inflammatory cells. Loss of cilia of airway epithelium and necrosis of type I alveolar epithelial cells are the most prominent consequences at the epithelial level. Inflammation is characterized by early neutrophilic infiltration, followed by an increased number of mononuclear cells, predominantly alveolar macrophages. After long-term exposure, whilst nitrogen dioxide causes predominantly emphysema, ozone produces mainly pulmonary fibrosis. Biochemical effects include lipid peroxidation, increased antioxidant metabolism, and alteration of enzyme activity. Nitrogen dioxide and ozone may also alter the immunological response and reduce the defence against infections, increasing the susceptibility of exposed animals to infections.

Animals↗
PubMed2005

Traffic air pollution and hospital admission for asthma: a case-control approach in a Turin (Italy) population.

OBJECTIVES: This study investigated the relationship between traffic air pollution and asthma, using a case-control design applied to routinely collected data. METHODS: Subjects resident in Turin during the period 1997-1999 and admitted for asthma were defined as cases; patients admitted for causes other than respiratory diseases or heart diseases were defined as controls. Nitrogen dioxide and total suspended particulate were considered as indicators of traffic air pollution. Statistical analysis were performed, separately for young (0-14 years), adult (15-64 years) and elderly (>64 years) patients, with a logistic regression model; results are expressed as percentage of risk modification for a 10 g/m(3) increase in exposure to pollutants. RESULTS: The risk of emergency admissions for asthma rose significantly with increased exposure to nitrogen dioxide [2.4%, 95% Confidence Interval: 0.5%; 4.3%], and total suspended particulate [2.3%, 95% Confidence Interval: 1.1%-3.6%]. The significant association was evident, in particular, among young and elderly patients for both pollutants. CONCLUSION: Using a case-control design both easy to use and manage, the study confirms the significant association between hospital emergency admissions for asthma and exposure to nitrogen dioxide and total suspended particulate pollutants.

Adolescent↗
PubMed2004

Cumulative exposure to dust and gases as determinants of lung function decline in tunnel construction workers.

AIMS: To study the relation between lung function decrease and cumulative exposure to dust and gases in tunnel construction workers. METHODS: A total of 651 male construction workers (drill and blast workers, tunnel concrete workers, shotcreting operators, and tunnel boring machine workers) were followed up by spirometric measurements in 1989-2002 for an average of six years. Outdoor concrete workers, foremen, and engineers served as a low exposed referent population. RESULTS: The between worker component of variability was considerably reduced within the job groups compared to the whole population, suggesting that the workers within job groups had similar exposure levels. The annual decrease in FEV1 in low-exposed non-smoking workers was 21 ml and 24 ml in low-exposed ever smokers. The annual decrease in FEV1 in tunnel construction workers was 20-31 ml higher than the low exposed workers depending on job group for both non-smokers and ever smokers. After adjustment for age and observation time, cumulative exposure to nitrogen dioxide showed the strongest association with a decrease in FEV1 in both non-smokers, and ever smokers. CONCLUSION: Cumulative exposure to nitrogen dioxide appeared to be a major risk factor for lung function decreases in these tunnel construction workers, although other agents may have contributed to the observed effect. Contact with blasting fumes should be avoided, diesel exhaust emissions should be reduced, and respiratory devices should be used to protect workers against dust and nitrogen dioxide exposure.

Adult↗