Water Vapor, Clouds, and Saturation in the Tropical Tropopause Layer.

The goal of this investigation is to understand the mechanism behind the observed high relative humidity with respect to ice (RHi) in the tropical region between ~14 km (150 hPa) and the tropopause, often referred to as the tropical tropopause layer (TTL). As shown by satellite, aircraft and balloon observations, high (>80%) RHi regions are widespread within the TTL. Regions with the highest RHi are co-located with extensive cirrus. During boreal winter, the TTL RHi is highest over the Tropical Western Pacific (TWP) with a weaker maximum over South America and Africa. In the winter, TTL temperatures are coldest and upward motion is the greatest in the TWP. It is this upward motion, driving humid air into the colder upper troposphere that produces the persistent high RHi and cirrus formation. Back trajectory calculations show that comparable adiabatic and diabatic processes contribute to this upward motion. We construct a bulk model of TWP TTL water vapor transport that includes cloud nucleation and ice microphysics that quantifies how upward motion drives the persistent high RHi in the TTL region. We find that atmospheric waves triggering cloud formation regulate the RHi, and that convection dehydrates the TTL. Our forward domain-filling trajectory (FDF) model is used to more precisely simulate the TTL spatial and vertical distribution of RHi. The observed RHi distribution is reproduced by the model and we show that convection increases RHi below the base of the TTL with little impact on the RHi in the TTL region.

Evaluation of UT/LS hygrometer accuracy by intercomparison during the NASA MACPEX mission.

Acquiring accurate measurements of water vapor at the low mixing ratios (< 10 ppm) encountered in the upper troposphere and lower stratosphere (UT/LS) has proven to be a significant analytical challenge evidenced by persistent disagreements between high-precision hygrometers. These disagreements have caused uncertainties in the description of the physical processes controlling dehydration of air in the tropical tropopause layer and entry of water into the stratosphere and have hindered validation of satellite water vapor retrievals. A 2011 airborne intercomparison of a large group of in situ hygrometers onboard the NASA WB-57F high-altitude research aircraft and balloons has provided an excellent opportunity to evaluate progress in the scientific community toward improved measurement agreement. In this work we intercompare the measurements from the Midlatitude Airborne Cirrus Properties Experiment (MACPEX) and discuss the quality of agreement. Differences between values reported by the instruments were reduced in comparison to some prior campaigns but were nonnegligible and on the order of 20% (0.8 ppm). Our analysis suggests that unrecognized errors in the quantification of instrumental background for some or all of the hygrometers are a likely cause. Until these errors are understood, differences at this level will continue to somewhat limit our understanding of cirrus microphysical processes and dehydration in the tropical tropopause layer.

Prevalence and incidence of respiratory symptoms in relation to indoor dampness: the RHINE study.

BACKGROUND: An association between indoor dampness and respiratory symptoms has been reported, but dampness as a risk factor for the onset or remission of respiratory symptoms and asthma is not well documented. METHOD: This follow up study included 16 190 subjects from Iceland, Norway, Sweden, Denmark, and Estonia who had participated in the European Community Respiratory Health Survey (ECRHS I). Eight years later the same subjects answered a postal questionnaire that included questions on respiratory symptoms and indicators of indoor dampness. RESULTS: Subjects living in damp housing (18%) had a significantly (p<0.001) higher prevalence of wheeze (19.1% v 26.0%), nocturnal breathlessness (4.4% v 8.4%), nocturnal cough (27.2% v 36.5%), productive cough (16.6% v 22.3%) and asthma (6.0% v 7.7%). These associations remained significant after adjusting for possible confounders. Indoor dampness was a risk factor for onset of respiratory symptoms but not for asthma onset in the longitudinal analysis (OR 1.13, 95% CI 0.92 to 1.40). Remission of nocturnal symptoms was less common in damp homes (OR 0.84, 95% CI 0.73 to 0.97). CONCLUSIONS: Subjects living in damp housing had a higher prevalence of respiratory symptoms and asthma. Onset of respiratory symptoms was more common and remission of nocturnal respiratory symptoms was less common in subjects living in damp housing.

Insomnia is more common among subjects living in damp buildings.

BACKGROUND: Insomnia is a condition with a high prevalence and a great impact on quality of life. Little is known about the relation between and sleep disturbances and the home environment. AIM: To analyse the association between insomnia and building dampness. METHODS: In a cross-sectional, multicentre, population study, 16 190 subjects (mean age 40 years, 53% women) were studied from Reykjavik in Iceland, Bergen in Norway, Umeå, Uppsala, and Göteborg in Sweden, Aarhus in Denmark, and Tartu in Estonia. Symptoms related to insomnia were assessed by questionnaire. RESULTS: Subjects living in houses with reported signs of building dampness (n = 2873) had a higher prevalence of insomnia (29.4 v 23.6%; crude odds ratio 1.35, 95% CI 1.23 to 1.48). The association between insomnia and different indicators of building dampness was strongest for floor dampness: "bubbles or discoloration on plastic floor covering or discoloration of parquet floor" (crude odds ratio 1.96, 95% CI 1.66 to 2.32). The associations remained significant after adjusting for possible confounders such as sex, age, smoking history, housing, body mass index, and respiratory diseases. There was no significant difference between the centres in the association between insomnia and building dampness. CONCLUSION: Insomnia is more common in subjects living in damp buildings. This indicates that avoiding dampness in building constructions and improving ventilation in homes may possibly have a positive effect on the quality of sleep.

Obesity and nocturnal gastro-oesophageal reflux are related to onset of asthma and respiratory symptoms.

Several studies have identified obesity as a risk factor for asthma in both children and adults. An increased prevalence of asthma in subjects with gastro-oesophageal reflux (GOR) and obstructive sleep apnoea syndrome has also been reported. The aim of this investigation was to study obesity, nocturnal GOR and snoring as independent risk factors for onset of asthma and respiratory symptoms in a Nordic population. In a 5-10 yr follow-up study of the European Community Respiratory Health Survey in Iceland, Norway, Denmark, Sweden and Estonia, a postal questionnaire was sent to previous respondents. A total of 16,191 participants responded to the questionnaire. Reported onset of asthma, wheeze and night-time symptoms as well as nocturnal GOR and habitual snoring increased in prevalence along with the increase in body mass index (BMI). After adjusting for nocturnal GOR, habitual snoring and other confounders, obesity (BMI >30) remained significantly related to the onset of asthma, wheeze and night-time symptoms. Nocturnal GOR was independently related to the onset of asthma and in addition, both nocturnal GOR and habitual snoring were independently related to onset of wheeze and night-time symptoms. This study adds evidence to an independent relationship between obesity, nocturnal gastro-oesophageal reflux and habitual snoring and the onset of asthma and respiratory symptoms in adults.

Role of the stratospheric polar freezing belt in denitrification.

Homogeneous freezing of nitric acid hydrate particles can produce a polar freezing belt in either hemisphere that can cause denitrification. Computed denitrification profiles for one Antarctic and two Arctic cold winters are presented. The vertical range over which denitrification occurs is normally quite deep in the Antarctic but limited in the Arctic. A 4 kelvin decrease in the temperature of the Arctic stratosphere due to anthropogenic and/or natural effects can trigger the occurrence of widespread severe denitrification. Ozone loss is amplified in a denitrified stratosphere, so the effects of falling temperatures in promoting denitrification must be considered in assessment studies of ozone recovery trends.

Bronchial reactivity to cigarette smoke; relation to lung function, respiratory symptoms, serum-immunoglobulin E and blood eosinophil and leukocyte counts.

STUDY OBJECTIVES: The aim of the study was to investigate the relationship between the immediate bronchial response to inhaled cigarette smoke [cigarette smoke bronchial reactivity (CBR)] and lung function, respiratory symptoms and markers of allergy and inflammation. DESIGN, PARTICIPANTS AND MEASUREMENTS: This cross-sectional study included 98 smokers. Their lung function and reversibility to inhaled terbutaline was measured. Their clinical history was obtained, an allergological examination was done, and bronchial reactivity to methacholine and inhaled cigarette smoke was measured. Questionnaires about respiratory symptoms, smoking history and drug usage were completed and a blood sample was obtained. Participants were divided into three groups: with asthma, chronic bronchitis and persons without asthma or chronic bronchitis (the respiratory healthy). RESULTS: Forced expiratory volume in 1sec (FEV1) residuals were independently related to the % fall in FEV1 after 12 cigarette smoke inhalations (DFEV%) in all participants (P<001), in asthmatic smokers (P<0.01) and in smokers with chronic bronchitis (P<0.05). In smokers with asthma and chronic bronchitis FEV1 residuals explained 51% and 13% of the variation in DFEV%, respectively, but only 8% (P<0.05) and 1% (N.S.) of the variation in the methacholine bronchial reactivity. In the total population the presence of wheeze (P<0.01), attacks of breathlessness (P<0.05) and daily expectoration (P<0.001) were related to higher DFEV% readings. Serum immunonoglobulin (ES-IgE) was independently related to DFEV% in all participants (P<0.01), in smokers with chronic bronchitis (P<0.01) and in the respiratory healthy (0.05

Bronchial reactivity to cigarette smoke in smokers: repeatability, relationship to methacholine reactivity, smoking and atopy.

Bronchial reactivity to cigarette smoke (CBR) in a cross-section of 98 smokers has been investigated. All participants were subjects to skin-prick tests to common allergens, lung function measurements and bronchial challenges with methacholine and cigarette smoke. In 38 participants a rechallenge with cigarettes was performed 1 h after the first cigarette challenge. Lung function indices analysed were: forced expiratory volume in one second (FEV1); maximal expiratory flow at 75% of the forced vital capacity (MEF75%); and forced mid-expiratory flow between 25 and 75% of the forced vital capacity (FEF(25-75%)). All participants were tested for asthma and allergy, and were required to provide information regarding respiratory symptoms, first degree relatives with asthma and allergy and smoking habits. A substantial decrease was seen in all lung function indices after 12 cigarette-smoke inhalations, but only FEV1 was related to other variables. The maximal mean percentage fall in FEV1 was 10%, which was directly related to the number of inhalations (p<0.05). In multiple regression analyses the percentage fall in FEV1 was directly related to: FEV1/vital capacity (VC) (p<0.01); to the asthmatic/bronchitic status (p<0.05); and to the accumulated and standardized cigarette consumption (p<0.05). The percentage fall in FEV1 bore no relationship to methacholine bronchial reactivity, sex or age and had a continuous distribution. The repeat challenge showed a smaller fall in FEV1 compared to the first challenge after 12 cigarette smoke inhalations (p<0.05). The percentage fall in FEV1 correlated after the first and the repeat challenge (p<0.05). Repeatability of the challenge could not be determined in this study because of tachyphylaxis. Bronchial reactivity to cigarette smoke is a tobacco smoke-specific bronchial response. All participants responded and the response showed a continuous distribution. Bronchial reactivity to cigarette smoke may be of importance for symptoms and prognosis in chronic bronchitis and chronic obstructive pulmonary disease and should be studied in relation to the degree of accelerated lung function loss in smokers and other cigarette induced lung abnormalities.

Blood eosinophil and monocyte counts are related to smoking and lung function.

The aim of this study was to investigate the predictive value of peripheral eosinophil and monocyte blood counts regarding lung function in smokers and non-smokers, and to investigate the influence of smoking on these cell counts. Forced expiratory volume in 1 s (FEV1) measurements and blood samples were collected from 298 non-atopic smokers and 136 never-smokers. Blood samples were repeated in 160 smokers after cessation of smoking (quitters) and 30 continuing smokers, 2, 6, 12 and 26 weeks after smoking cessation. Monocyte (P < 0.05) but not eosinophil blood counts were higher in never-smokers compared to smokers. In never-smokers, blood eosinophil counts and monocyte counts correlated inversely (P < 0.05) and directly (P < 0.01), respectively, with standardized FEV1 residuals (FEVR). In smokers, blood eosinophil (P < 0.05) and monocyte (P < 0.05) counts correlated directly with FEVR independent of smoking history. After smoking cessation, monocyte blood counts (P < 0.05) increased. Both eosinophil and monocyte blood counts showed a greater increase in quitters with decreased lung function (P < 0.05). Former heavy smokers had higher blood eosinophil (P < 0.05) but lower monocyte (P < 0.05) count increase than had former light smokers. These data suggest that smoking influences eosinophil and monocyte blood counts and that this is associated with a small negative effect on lung function. Eosinophil blood counts had an opposite relation to lung function in smokers and non-smokers. Further research should include investigations of relations between smoking and stimulatory factors for recruitment and activity of eosinophils and monocytes.

Prospective study on the effect of smoking and nicotine substitution on leucocyte blood counts and relation between blood leucocytes and lung function.

BACKGROUND: The influence of smoking and of nicotine substitution on the counts of total blood leucocytes and leucocyte subsets and the relations between the counts and lung function was investigated. METHODS: The study was a combined cross sectional and prospective study of 298 smokers and 136 non-smokers. Forced expiratory volume in one second (FEV1) was measured in all participants at baseline and six months after quitting smoking in 160 ex-smokers (quitters) and 138 persons with smoking relapse. Blood samples were obtained from all participants at baseline and from 160 quitters and 30 continuing smokers two, six, 12, and 26 weeks after smoking cessation and from 92 quitters one year after the cessation of smoking. RESULTS: Blood leucocyte counts and leucocyte subsets were all higher in smokers than in non-smokers. In cigarette smokers total leucocyte, neutrophil, and lymphocyte blood counts showed a dose dependent relationship with the daily cigarette consumption and pack years consumption. In smokers the neutrophil blood count was independently associated negatively with FEV1 residuals. After quitting smoking total leucocyte, neutrophil, and lymphocyte blood counts decreased during the first 26 weeks and after one year lymphocyte blood counts were higher than in non-smokers. In quitters substituted with nicotine chewing gum (2 mg) the accumulated number of pieces of chewing gum used in the 12 weeks had an inverse relationship with the decrease in the total lymphocyte blood count at 12 weeks after smoking cessation. CONCLUSIONS: Leucocyte blood counts are raised in smokers and decrease after smoking cessation. Neutrophil blood counts had an inverse relationship with lung function and nicotine may increase lymphocyte blood counts in smokers.

Serum eosinophilic cationic protein and lactoferrin related to smoking history and lung function.

Some smokers have an accelerated loss of lung function, possibly due to a chronic bronchial inflammation in which granulocytes are involved. Eosinophil cationic protein (ECP) and lactoferrin (LF) are granule proteins in the eosinophil and neutrophil granulocyte, respectively. We wanted to investigate the relationship of serum (s) ECP and LF concentrations to smoking history and lung function alteration. This partly cross-sectional and partly prospective study included 98 nonatopic smokers and 31 lifetime nonsmokers. As participants in a smoking cessation programme, 50 of the 98 smokers ceased smoking for > or = 1 year. Smoking history, lung function and blood samples were obtained at the start of the study, and smokers and ex-smokers also gave blood samples 3, 6 and 12 months later. s-ECP and s-LF were elevated in smokers compared to people who had never smoked. s-ECP was linearly associated with daily cigarette consumption and forced expiratory volume in one second (FEV1) residuals. In a multiple linear regression analysis, low s-ECP and high s-LF were associated with decreased FEV1 residuals. s-ECP and s-LF together accounted for 10.2% of the variation in FEV1 residuals. After smoking cessation, s-ECP and s-LF decreased within 6 months. s-ECP and s-LF are raised in smokers, and may serve as indicators of granulocyte activation. We speculate that they might contribute to prediction of accelerated lung function loss in smokers, but this question needs further investigation in a prospective study.

Investigation of smoking habits among 14-17-year-old boarding school pupils: factors which influence smoking status.

A questionnaire-based investigation was performed to elucidate factors with possible influence on smoking status in 557 14-17-year-old boarding school pupils. A representative sample of boarding school pupils in Denmark participated. Before entering boarding school an increased risk of being a smoker was present if a majority of one's schoolmates were smokers (odds ratio 5.9; P < 0.0001); if parents were not living together (odds ratio 2.1; P < 0.005); if older brother or sister was a smoker (odds ratio 3.1; P < 0.0001); and if both parents smoked (odds ratio 1.9; P < 0.01). After changing to boarding school there was an increased risk of starting to smoke if a majority of the schoolmates were smokers (odds ratio 4.6; P < 0.0001). Believing that smoking causes damage to the smokers' own health decreased the risk (odds ratio 2.9; P < 0.01). More efficient smoking prevention programmes should be created by aiming particularly at the special problems encountered in certain age groups, and possibly through a better understanding of the influence that psycho-social factors may have on youngsters' risk of becoming smokers.

Serum IgE in nonatopic smokers, nonsmokers, and recent exsmokers: relation to lung function, airway symptoms, and atopic predisposition.

The influence of smoking on serum IgE (s-IgE) was studied in a selected nonatopic population. The variation in s-IgE was followed during 1 year of smoking abstinence. The study included 287 smokers and 137 never smokers. IgE was higher in smokers compared with IgE in never smokers (p less than 0.005). Male smokers had higher s-IgE than female smokers (p less than 0.01). S-IgE was independent of age and claims of atopy among first-degree relatives. Weighted pack-years consumption was defined for cigarette smokers by modifying pack-years consumption by nicotine content of the brand smoked. Weighted pack-years consumption was associated with level of s-IgE (p less than 0.05). S-IgE was higher in smokers with airway symptoms compared with that in smokers without symptoms (p less than 0.01). In smokers older than 50 years of age, there tended to be decreased FEV1 residuals (0.05 less than p less than 0.06), and presence of airway symptoms was (p less than 0.03) associated with high levels of s-IgE independent of each other. In 92 quitters, s-IgE increased during the first 26 weeks of abstinence (p less than 0.05), and after 1 year, s-IgE had returned to baseline. The increase was only observed in smokers younger than 40 years and had no relation to variations in FEV1 during the 1-year follow-up. The increase in s-IgE after smoking cessation was transient, of minor clinical importance, and probably caused by a relief from an immunosuppressive influence.

The effect of nicotine, silver acetate, and placebo chewing gum on the cessation of smoking. The influence of smoking type and nicotine dependence.

The effects of nicotine (NI), silver acetate (SA), and ordinary (PL) chewing gum on the cessation of smoking were compared through ratings on six smoking types and physiological nicotine dependence (F-score) in a placebo-controlled and randomized study that included 496 smokers in a group-support setting. Results were evaluated after 26 weeks. Ratings on smoking types 1, 3, 4, 5, and 6 and F-score were related to success rates. The effect of NI was superior to SA in smokers with high type 1 ratings, the effects of NI and SA were almost equal and superior to PL in smokers with high type 4 and 6 ratings, and the effect was independent of the F-score. Treatment of smokers with NI and SA should be restricted to smoking types in which an effect superior to PL is documented, and research should be performed to find support for smoking types where SA and NI have a clear effect.

Effect on smoking cessation of silver acetate, nicotine and ordinary chewing gum. Influence of smoking history.

In a randomized smoking cessation study 211, 203 and 82 persons were supported with nicotine, silver acetate and ordinary chewing gum, respectively. After 26 weeks there was no overall difference in number of abstainers between treatments. Participants were divided into subsets with low and high weighted packyears consumption (WPY) which modifies tobacco consumption by nicotine content. Abstainer rates in the total population controlled for treatment decreased with increasing WPY (P less than 0.005). In participants with low WPY abstainer rate was higher in the silver acetate group compared to the nicotine (P less than 0.0005) and ordinary (P less than 0.05) chewing gum groups. Nicotine chewing gum was more effective than silver acetate (P less than 0.05) and ordinary (P less than 0.05) chewing gum in smokers with high WPY. Ratings on some inconveniences experienced during earlier attempts to quit smoking influenced the ability to break the habit but had no influence on chewing gum effects. This study indicated that through consideration of smoking history it should be possible to individualize pharmacological support to smokers wanting to quit, with silver acetate chewing gum most effective for smokers with a low WPY and nicotine chewing gum most effective for smokers with a high WPY.

Effect of nicotine, silver acetate, and ordinary chewing gum in combination with group counselling on smoking cessation.

Four hundred and ninety six smokers participated in a randomised comparison of the effect of silver acetate, nicotine, and ordinary chewing gum on smoking cessation. All were motivated to stop smoking abruptly and all had smoked at least 10 cigarettes a day for at least five years. Side effects and taste acceptability were related to outcome after six months. The participants attended nine meetings over a year, at which lectures, support, and advice about stopping smoking were given. Tobacco abstinence was confirmed by measurement of carbon monoxide in expired air. The chewing gums were used for 12 weeks. After 12 weeks there was a trend towards more abstainers in the nicotine group (59%) than in the silver acetate (50%) and ordinary (45%) chewing gum groups that was not quite significant (p = 0.07). At 26 and 52 weeks the number of cigarette abstainers was similar in the three treatment groups. Subjects in the nicotine chewing gum group had a longer mean time before relapse than those in the silver acetate and ordinary chewing gum groups. Mean success rates for all subjects combined at 12, 26, and 52 weeks were 52.8%, 39.7%, and 23.3%. The side effects of nicotine and silver acetate chewing gum were generally mild and transient, and unimportant except for mouth irritation from silver acetate, which had a negative effect on outcome, and the low taste acceptability of nicotine, which had a strong negative influence on the success rate. The results suggest a short term effect on nicotine chewing gum on smoking cessation, but the abstinence rates after one year were generally disappointing.

Lung function and bronchial reactivity in farmers.

The purpose of this study was to evaluate the prevalence and type of lung function disorders in Danish farmers. Three samples of farmers were drawn from a group of unselected farmers who had participated in an epidemiological study. Group I (47 persons) was a sample of the 8% of all farmers who had reported that they had asthma; group II (63 persons) was a sample of the 28% of farmers who had had wheezing, shortness of breath, or cough without phlegm; and group III (34 persons) a sample of the farmers (64% of the total) who had no asthma and no respiratory symptoms. The farmers with symptoms (groups I and II) had low mean levels of FEV1 and high values for residual volume, whereas the symptomless farmers had normal lung function and no airways obstruction. The proportion of farmers with an FEV1 below the 95% confidence limit for predicted values was 43% in group I and 23% in group II; there were none in group III. Bronchial hyperreactivity to histamine occurred in 96% of asthmatic farmers, 67% of farmers with wheezing or shortness of breath, and 59% of symptomless farmers. A low level of FEV1 was associated with the number of years in pig farming and bronchial hyperreactivity in group II but not group I or III. Most of the bronchial hyperreactivity was explained in the multiple regression analysis by a low FEV1, though this was significant only for farmers in group II. Thus farmers who reported asthma, wheezing, shortness of breath, or a dry cough in general had airways obstruction with an increased residual volume, whereas symptomless farmers had normal lung function. Severe bronchial hyperreactivity was mostly explained by a diagnosis of asthma and poor lung function, though some farmers with normal lung function and no respiratory symptoms had increased bronchial reactivity.

Serum concentrations and accumulation of silver in skin during three months treatment with an anti-smoking chewing gum containing silver acetate.

Silver acetate chewing gum was used for 12 weeks as a smoking deterrent in 21 adults. The effect of silver on serum concentrations, its accumulation in the skin and the risk of developing clinically evident argyria were investigated. Serum concentrations of silver clearly rose after chewing gum use had started, and concentrations quickly returned to normal after use had ceased. In most cases the number of silver granules in skin biopsies, observed by autometallography, increased after the gum had been used for 12 weeks. No one developed clinical signs of argyria. Silver acetate containing remedies can be used as an aid to stop smoking, but the consumption must be monitored to avoid accumulation of larger amounts of silver in the body.