Effect of whole-body exposure to cold and wind on lung function in asthmatic patients

Asthma triggered by extreme temperatures: From epidemiological evidence to biological plausibility

BACKGROUND

There is rapidly growing evidence indicating that extreme temperature is a crucial trigger and potential activator of asthma; however, the effects of extreme temperature on asthma are inconsistently reported and the its potential mechanisms remain undefined.

OBJECTIVES

This review aims to estimate the impacts of extreme heat, extreme cold, and temperature variations on asthma by systematically summarizing the existing studies from epidemiological evidence to biological plausibility.

METHODS

We conducted a systematic search in PubMed, Embase, and Web of Science from inception to June 30, 2022, and we retrieved articles of epidemiology and biological studies which assessed associations between extreme temperatures and asthma. This protocol was registered with PROSPERO (CRD42021273613).

RESULTS

From 12,435 identified records, 111 eligible studies were included in the qualitative synthesis, and 37 articles were included in the meta-analysis (20 for extreme heat, 16 for extreme cold, and 15 for temperature variations). For epidemiological evidence, we found that the synergistic effects of extreme temperatures, indoor/outdoor environments, and individual vulnerabilities are important triggers for asthma attacks, especially when there is extreme heat or cold. Meta-analysis further confirmed the associations, and the pooled relative risks for asthma attacks in extreme heat and extreme cold were 1.07 (95%CI: 1.03-1.12) and 1.20 (95%CI: 1.12-1.29), respectively. Additionally, this review discussed the potential inflammatory mechanisms behind the associations between extreme temperatures and asthma exacerbation, and highlighted the regulatory role of immunological pathways and transient receptor potential ion channels in asthma triggered by extreme temperatures.

CONCLUSIONS

We concluded that both extreme heat and cold could significantly increase the risk of asthma. Additionally, we proposed a potential mechanistic framework, which is important for understanding the disease pathogenesis that uncovers the complex mechanisms of asthma triggered by extreme temperatures and protects the sensitive individuals from impacts of extreme weather events and climate change.

Acute effects of ambient temperature on lung function of a panel of school children living in Dhaka, Bangladesh

INTRODUCTION

Short-term exposure to ambient temperature plays a significant role in human health. However, studies examining ambient temperature and lung function are scarce in locations with a tropical environment. To address this research gap, the current study investigated the effects of short-term ambient temperature on lung function in children and seasonal variation in this association in Dhaka, Bangladesh.

METHODS

The study was conducted in three schools located in three cities inside and around Dhaka. Repeated lung function measurements were obtained from a panel of 315 school children (including 86 asthmatic children) aged 9-16 years in 2013. Linear mixed-effects models adjusted for potential confounders were used to examine the effect of ambient temperature on lung function.

RESULTS

Short-term exposure to low ambient temperature was associated with a significant decrement in children's lung function. For each 1 °C decrease in daily mean temperature at cumulative lag of the current and previous day, lung function parameter values were -3.02% (95% CI, -1.69 to -4.35) for peak expiratory flow (PEF), and -1.48% (95% CI, -0.75 to -2.22) for forced expiratory volume within 1 s (FEV1). A significant seasonal variation was also observed in these associations, as the estimated adverse effects of decrease in daily mean temperature on lung function measures were primarily evident in winter.

DISCUSSION

This study suggests that short-term ambient exposure to decrease in temperature adversely affect lung function. A significant seasonal modification in the association between temperature and lung function was also observed for these children living in an environment with a tropical climatic condition as the adverse effect of decrease in ambient temperature was primarily observed in winter than in summer.

Cold air exposure at - 15 °C induces more airway symptoms and epithelial stress during heavy exercise than rest without aggravated airway constriction

Purpose

Exposure to cold air may harm the airways. It is unclear to what extent heavy exercise adds to the cold-induced effects on peripheral airways, airway epithelium, and systemic immunity among healthy individuals. We investigated acute effects of heavy exercise in sub-zero temperatures on the healthy airways.

Methods

Twenty-nine healthy individuals underwent whole body exposures to cold air in an environmental chamber at − 15 °C for 50 min on two occasions; a 35-min exercise protocol consisting of a 5-min warm-up followed by 2 × 15 min of running at 85% of VO₂max vs. 50 min at rest. Lung function was measured by impulse oscillometry (IOS) and spirometry before and immediately after exposures. CC16 in plasma and urine, and cytokines in plasma were measured before and 60 min after exposures. Symptoms were surveyed pre-, during and post-trials.

Results

FEV₁ decreased after rest (− 0.10 ± 0.03 L, p < 0.001) and after exercise (− 0.06 ± 0.02 L, p = 0.012), with no difference between trials. Exercise in − 15 °C induced greater increases in lung reactance (X5; p = 0.023), plasma CC16 (p < 0.001) as well as plasma IL-8 (p < 0.001), compared to rest. Exercise induced more intense symptoms from the lower airways, whereas rest gave rise to more general symptoms.

Conclusion

Heavy exercise during cold air exposure at − 15 °C induced signs of an airway constriction to a similar extent as rest in the same environment. However, biochemical signs of airway epithelial stress, cytokine responses, and symptoms from the lower airways were more pronounced after the exercise trial.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00421-022-05004-3.

Asthma, allergy and vitamin E: Current and future perspectives

Asthma and allergic disease result from interactions of environmental exposures and genetics. Vitamin E is one environmental factor that can modify development of allergy early in life and modify responses to allergen after allergen sensitization. Seemingly varied outcomes from vitamin E are consistent with the differential functions of the isoforms of vitamin E. Mechanistic studies demonstrate that the vitamin E isoforms α-tocopherol and γ-tocopherol have opposite functions in regulation of allergic inflammation and development of allergic disease, with α-tocopherol having anti-inflammatory functions and γ-tocopherol having pro-inflammatory functions in allergy and asthma. Moreover, global differences in prevalence of asthma by country may be a result, at least in part, of differences in consumption of these two isoforms of tocopherols. It is critical in clinical and animal studies that measurements of the isoforms of tocopherols be determined in vehicles for the treatments, and in the plasma and/or tissues before and after intervention. As allergic inflammation is modifiable by tocopherol isoforms, differential regulation by tocopherol isoforms provide a foundation for development of interventions to improve lung function in disease and raise the possibility of early life dietary interventions to limit the development of lung disease.

Lung physiology and controlled exposure study design

Controlled human inhalation exposure ( CHIE) studies provide a unique opportunity to conduct formal experiments to examine the human health effects of airborne pollutants. Lung function, easily measured using spirometry, is a common physiological variable often utilized in these studies. By design, CHIE studies only induce mild and reversible acute effects, which may or may not predict adverse effects that may develop under chronic exposure conditions. There is substantial inter- and intra-individual variability in functional capacity and symptoms such as chest tightness and dyspnea, which are complex variables that are affected by individual perception, physiological lung impairment, and other variables (e.g., concomitant health conditions, and level of conditioning/fitness). Thus, the design of the CHIE study and physiological and environmental factors of study participants can affect each CHIE study's results. Researchers can address many of these critical issues in the problem formulation phase of CHIE studies, utilizing existing information on the expected effects of the substance of interest and possible modes of action. Thoughtful design and interpretation of CHIE studies will increase their utility for evaluating and setting environmental health policy.

An experimental exposure study revealing composite airway effects of physical exercise in a subzero environment

Exposure to a cold climate is associated with an increased morbidity and mortality, but the specific mechanisms are largely unknown. People with cardiopulmonary disease and winter endurance athletes are particularly vulnerable. This study aimed to map multiple domains of airway responses to exercise in subzero temperature in healthy individuals.

Thirty-one healthy subjects underwent whole-body exposures for 50 minutes on two occasions in an environmental chamber with intermittent moderate-intensity exercise in +10 °C and -10 °C. Lung function, plasma/urine CC16 , and symptoms were investigated before and after exposures.

Compared to baseline, exercise in -10 °C decreased FEV₁ (p=0.002), FEV₁/FVC (p<0.001), and increased R20Hz (p=0.016), with no differences between exposures. Reactance increased after +10 °C (p=0.005), which differed (p=0.042) from a blunted response after exercise in -10 °C. Plasma CC16 increased significantly within exposures, without differences between exposures. Exercise in -10 °C elicited more intense symptoms from the upper airways, compared to +10 °C. Symptoms from the lower airways were few and mild. 

Short-duration moderate-intensity exercise in -10 °C induces mild symptoms from the lower airways, no lung function decrements or enhanced leakage of biomarkers of airway epithelial injury, and no peripheral bronchodilatation, compared to exercise in +10 °C. 

Exercise in Sub-zero Temperatures and Airway Health: Implications for Athletes With Special Focus on Heat-and-Moisture-Exchanging Breathing Devices

Asthma is highly prevalent among winter endurance athletes. This "occupational disease" of cross-country skiers, among others, was acknowledged during the 1990s, with the pathogenesis attributed to repeated and prolonged exposure to cold, dry air combined with high rates of ventilation during exercise. Nevertheless, more than 25 years later, the prevalence of asthma among Scandinavian cross-country skiers is unchanged, and prevention remains a primary concern for sports physicians. Heat-and-moisture-exchanging breathing devices (HMEs) prevent exercise-induced bronchoconstriction in subjects with pre-existing disease and may have potential as a preventative intervention for healthy athletes undertaking training and competition in winter endurance sports. Herein we firstly provide an overview of the influence of temperature and humidity on airway health and the implications for athletes training and competing in sub-zero temperatures. We thereafter describe the properties and effects of HMEs, identify gaps in current understanding, and suggest avenues for future research.

Climate Change to Blame in Severe Oral Corticosteroid-Dependent Asthma? A Case Report

Patient: Female, 63-year-old

Final Diagnosis: Asthma

Symptoms: Wheeze

Medication: —

Clinical Procedure: —

Specialty: Pulmonology

Qualitative identification and characterisation of self-reported symptoms arising in humans during experimental exposure to cold air

Background: Exposure to cold air is associated with increased morbidity and mortality in the general population. It is difficult to study the effects of whole-body exposure to cold air under controlled conditions in real life. Objectives: The aim of this study was to (1) explore and describe the experience of symptoms in humans during experimental and controlled exposures to cold air, by using controlled environmental chamber exposures and qualitative methodology, and to (2) categorise the symptoms. Method: The study used a randomised, double blind design, in which 34 subjects undertook rest and moderate-intensity exercise in an environmental chamber set to two or three different temperatures (0, −10, and −17°C) on separate occasions. During the chamber exposures, subjects were interviewed. Qualitative content analysis was selected as the method of analysis. Findings: Subjects reported 50 distinct symptoms during the exposures. The symptoms were grouped into ten sub-categories and two major categories; airway versus whole-body symptoms. Conclusion: We have identified a broad range of symptoms in humans undertaking rest and moderate-intensity exercise at sub-zero temperatures. The symptoms and their categories may well be used to more extensively and quantitatively map cold-induced morbidity.

[Meteorological variables and air pollution and their association with hospitalizations due to respiratory diseases in children: a case study in São Paulo, Brazil]

Urban climate changes, excessive air pollution, and increasing social inequalities have become determinant factors in the high risk of hospitalizations due to respiratory diseases. The current study thus aimed to understand how meteorological factors (air temperature, relative humidity, and precipitation) and air pollution (particulate matter with aerodynamic diameter less than 10µm - PM10) are related to hospitalizations due to respiratory diseases in children in 14 districts in the city of São Paulo, Brazil. The combination of generalized linear models with a negative binomial distribution and distributed lag non-linear model (DLNM) were used as the statistical method to analyze the relationship between hospitalizations, climatic factors, and pollution from 2003 to 2013. The results show statistically significant association with high relative risk between mean air temperature (17.5ºC to 21ºC, for the total analyzed), relative humidity (84% to 98% for females), precipitation (0mm to 2.3mm for the total and both sexes and > 120mm for females), and PM10 (> 35µg/m³ for the total and for females). These results showed that environmental factors contribute to the high risk of hospitalizations.

Estimating the spatial distribution of environmental suitability for female lung cancer mortality in China based on a novel statistical method

Lung cancer as one of the major causes of cancer mortality has been demonstrated to be closely related to the ambient atmospheric environment, but little has been done in the synthetic evaluation of the linkage between cancer mortality and combined impact of ambient air pollution and meteorological conditions. The present study determined the environmental suitability for female lung cancer mortality associated with air contaminants and meteorological variables. A novel fuzzy matter-element method was applied to identify the spatial distribution and regions for the environmental suitability for the female lung cancer mortality across China in 2013. The membership functions between the cancer mortality and 6 environmental factors, including PM_2.5, NO₂, SO₂, PM₁₀, the annual mean wind speed, and mean temperature, were generated and the weights of each of the environmental factors were established by the maximum entropy (MaxEnt) model. We categorized the environmental suitability combined with GIS spatial analysis into three zones, including low-suitable, medium-suitable, and high-suitable region where the cancer mortality ranging from low to high rate was identified. These three zones were quantified by the MaxEnt model taking different air pollutants and meteorological variables into consideration. We identified that NO₂ was a most significant factor among the 6 environmental factors with the weight of 24.88%, followed by the annual mean wind speed, SO₂, and PM_2.5. The high-suitable area, mainly in the North China Plain which is a most heavily contaminated region by air pollution in China, covers 1.6195 million square kilometers, accounting for 17.85% of the total area investigated in this study. Identification of the impact of various environmental factors on cancer mortality in the different suitable area provides a scientific basis for the environmental management, risk assessment, and lung cancer control.

Different sensitivities to ambient temperature between first- and re-admission childhood asthma cases in Hong Kong - A time series study

OBJECTIVES

Asthma can be triggered by various factors due to different etiologies. Environmental factors remain a common trigger of asthma, especially amongst children, and such ambient exposures can be harder to avoid compared to behavioral triggers. As such, the contribution of environmental factors may be enhanced when considering repeat asthma cases compared to initial presentations. To test this hypothesis, we assessed associations between ambient temperature and hospital admissions for asthma in Hong Kong and stratified admission records into first and repeat asthma hospitalizations.

METHODS

The daily number of asthma hospitalizations among children aged 0-5 years in Hong Kong during 2007-2011 was regressed on daily mean temperature using distributed lagged nonlinear models, with adjustment for seasonal patterns, day-of-week effects, and other meteorological factors and air-pollutants. Analyses were stratified by summer/winter and by type of admission (first admission and repeated admission).

RESULTS

About 33% of the 12284 asthma hospitalizations were repeat admissions. Repeat admissions demonstrated higher sensitivity to high temperature in the summer. During this period, high temperatures were associated with increased risk of repeat admission but not with first admissions: RR (95% CI) comparing 31 °C vs. 29 °C across lags 0-15 days was 3.40 (1.26, 9.18) and 0.74 (0.31, 1.77) for repeat and first admissions respectively. In the cold season, all admissions increased with falls in temperature, with slightly stronger associations apparent for repeat admissions compared to first admission: 1.20 (1.00, 1.44) vs. 1.10 (0.96, 1.26) respectively comparing risk at 15 °C vs. 12 °C across lags 0-5 days.

CONCLUSIONS

To our knowledge, this is the first study to show stronger associations between ambient temperature and repeat asthma admissions compared to first admissions. The higher sensitivity among those experiencing repeat admissions may allow for more personalized disease management. Given the substantial differences in associations by admission type, future studies of ambient exposures on asthma should consider analyzing the two groups separately.

Cold weather increases respiratory symptoms and functional disability especially among patients with asthma and allergic rhinitis

Cold weather affects the respiratory epithelium and induces bronchial hyperresponsiveness. We hypothesized that individuals with allergic rhinitis or/and asthma experience cold weather-related functional disability (FD) and exacerbation of health problems (EH) more commonly than individuals without these. This was a population-based study of 7330 adults aged 25–74 years. The determinants of interest, including doctor-diagnosed asthma and allergic rhinitis, and the outcomes, including cold weather-related FD and EH, were measured using a self-administered questionnaire. The prevalences of cold-related FD and EH were 20.3% and 10.3%, respectively. In Poisson regression, the risk of FD increased in relation to both allergic rhinitis (adjusted prevalence ratio (PR) 1.19, 95% CI 1.04–1.37 among men; 1.26, 95% CI 1.08–1.46 among women), asthma (1.29, 0.93–1.80; 1.36, 0.92–2.02, respectively) and their combination (1.16, 0.90–1.50; 1.40, 1.12–1.76, respectively). Also the risk of cold weather-related EH was related to both allergic rhinitis (1.53, 1.15,−2.04 among men; 1.78, 1.43–2.21 among women), asthma (4.28, 2.88–6.36; 3.77, 2.67–5.34, respectively) and their combination (4.02, 2.89–5.59; 4.60, 3.69–5.73, respectively). We provide new evidence that subjects with allergic rhinitis or/and asthma are more susceptible to cold weather-related FD and EH than those without pre-existing respiratory diseases.

The association between ambient temperature and childhood asthma: a systematic review

The objectives of this study are to review available information on the association between ambient temperature and childhood asthma, and to elucidate the possible underlying mechanisms of this relationship. A systematic review was conducted based on the papers retrieved from four databases, including PubMed, ProQuest, ScienceDirect, and Scopus. Papers examining the association of absolute temperature or temperature variation with childhood asthma published from 1 January 2000 to 31 December 2016 were included. Thirteen papers have quantified the effect of absolute temperature on childhood asthma, and six papers have examined the effect of intra- or inter-day temperature variation on childhood asthma. All studies were conducted in urban areas. Aeroallergen sensitizations were only considered in the analyses of one study. Discrepancy existed in the significance of the relationship between absolute temperature and childhood asthma, and also in the shape of this relationship (i.e. linear or non-linear) and whether temperature effects were lagged. Increasing evidence is suggesting non-linear relationship between absolute temperature and childhood asthma. Future research should investigate the burden of childhood asthma specifically attributable to extreme temperatures and temperature variation using advanced statistical approach, particularly in rural areas, after properly considering aeroallergens and air pollution. Projecting future burden of childhood asthma under climate change scenarios is also warranted.

Oxidative Stress: Harms and Benefits for Human Health

Oxidative stress is a phenomenon caused by an imbalance between production and accumulation of oxygen reactive species (ROS) in cells and tissues and the ability of a biological system to detoxify these reactive products. ROS can play, and in fact they do it, several physiological roles (i.e., cell signaling), and they are normally generated as by-products of oxygen metabolism; despite this, environmental stressors (i.e., UV, ionizing radiations, pollutants, and heavy metals) and xenobiotics (i.e., antiblastic drugs) contribute to greatly increase ROS production, therefore causing the imbalance that leads to cell and tissue damage (oxidative stress). Several antioxidants have been exploited in recent years for their actual or supposed beneficial effect against oxidative stress, such as vitamin E, flavonoids, and polyphenols. While we tend to describe oxidative stress just as harmful for human body, it is true as well that it is exploited as a therapeutic approach to treat clinical conditions such as cancer, with a certain degree of clinical success. In this review, we will describe the most recent findings in the oxidative stress field, highlighting both its bad and good sides for human health.

Vitamin E: Emerging aspects and new directions

The discovery of vitamin E will have its 100th anniversary in 2022, but we still have more questions than answers regarding the biological functions and the essentiality of vitamin E for human health. Discovered as a factor essential for rat fertility and soon after characterized for its properties of fat-soluble antioxidant, vitamin E was identified to have signaling and gene regulation effects in the 1980s. In the same years the cytochrome P-450 dependent metabolism of vitamin E was characterized and a first series of studies on short-chain carboxyethyl metabolites in the 1990s paved the way to the hypothesis of a biological role for this metabolism alternative to vitamin E catabolism. In the last decade other physiological metabolites of vitamin E have been identified, such as α-tocopheryl phosphate and the long-chain metabolites formed by the ω-hydroxylase activity of cytochrome P-450. Recent findings are consistent with gene regulation and homeostatic roles of these metabolites in different experimental models, such as inflammatory, neuronal and hepatic cells, and in vivo in animal models of acute inflammation. Molecular mechanisms underlying these responses are under investigation in several laboratories and side-glances to research on other fat soluble vitamins may help to move faster in this direction. Other emerging aspects presented in this review paper include novel insights on the mechanisms of reduction of the cardiovascular risk, immunomodulation and antiallergic effects, neuroprotection properties in models of glutamate excitotoxicity and spino-cerebellar damage, hepatoprotection and prevention of liver toxicity by different causes and even therapeutic applications in non-alcoholic steatohepatitis. We here discuss these topics with the aim of stimulating the interest of the scientific community and further research activities that may help to celebrate this anniversary of vitamin E with an in-depth knowledge of its action as vitamin.

Association between children's forced vital capacity and long-term exposure to local ambient temperature in China: A national cross-sectional survey

It is well documented that short-term exposure to extreme ambient temperature is associated with respiratory disorder. However, few studies have assessed the long-term effect of temperature on children's lung function. The present study aimed to investigate the association between long-term exposure to local ambient temperature and children's forced vital capacity (FVC) in China. We analyzed the FVC data of 71,768 children from the 2010 Chinese National Survey on Students' Construction and Health (CHNSCH), and local annual average ambient temperature, relative humidity, air pollutants data from China Meteorological Administration and Ministry of Environment Protection of China. Generalized additive model (GAM) with non-linear function was used to examine the effect of ambient temperature on children's FVC. The results showed that low temperature was significantly associated with decrease of FVC in Chinese children within certain temperature range while adjusting for individual characteristics, socioeconomic conditions, air pollutants and relative humidity. The largest alteration of FVC related to the annual average temperature difference among cities from 20.4°C to 4.5°C was observed, being 242.7ml (95%CI: 220.0, 265.3) decrease in FVC. The similar association was found in both physically active and inactive children, while the largest alteration of FVC related to the temperature difference reached 329.1ml (95%CI: 296.7, 361.6) in physically active children and 290.5ml (95%CI: 255.7, 325.3) in physically inactive ones. Public health policy should be developed for protecting children's respiratory health during growth and development in some areas with cold weather. Key message What is the key question? Few studies have assessed the long-term effect of temperature on children's forced vital capacity (FVC). We analyzed the Chinese national survey data to clarify the association between children's forced vital capacity and long-term exposure to local ambient temperature. What is the bottom line? Our study found that low temperature was significantly associated with decrease of forced vital capacity in children of 30 cities in China. The largest alteration of FVC related to the temperature difference from 20.4°C to 4.5°C was observed, being 242.7ml (95%CI: 220.0, 265.3) decrease in FVC. Why read on? The presented study provide some evidence about long-term effect of temperature on children's respiratory health and public health policy should be developed for protecting children from adverse effects of low temperature on their respiratory health during growth and development in some areas with cold weather.

The short-term association between asthma hospitalisations, ambient temperature, other meteorological factors and air pollutants in Hong Kong: a time-series study

BACKGROUND

Previous studies have found associations between meteorological variables and asthma hospitalisations but the nature of these associations has varied and few studies have been done in subtropical areas or evaluated effect modification by age.

OBJECTIVES

This study aimed to evaluate associations between asthma hospitalisations and meteorological factors and to assess effect modification of these associations by age and season in Hong Kong.

METHODS

Poisson generalised additive models combined with distributed lag nonlinear models and piecewise linear models were used to model associations between daily asthma hospitalisations from 2004 to 2011 and meteorological factors and air pollutants, adjusting for day of week, seasonality and trend. Subgroup analyses by age and season were performed.

RESULTS

In the hot season, hospitalisations were lowest at 27°C, rose to a peak at 30°C, then plateaued between 30°C and 32°C. The cumulative relative risk for lags 0-3 days (RRlag0-3) for 30°C vs 27°C was 1.19 (95% CI 1.06 to 1.34). In the cold season, temperature was negatively associated with asthma hospitalisations. The cumulative RRlag0-3 for 12°C vs 25°C was 1.33 (95% CI 1.13 to 1.58). Adult admissions were most sensitive to temperatures in both seasons while admissions among children under 5 were least associated. Higher humidity and ozone levels in the hot season, and low humidity in the cold season were also associated with more asthma admissions.

CONCLUSIONS

People with asthma should avoid exposure to adverse conditions by limiting outdoor activities during periods of extreme temperatures, combinations of high humidity and high temperature, and low humidity and low temperature, and high ozone levels.

Air quality and temperature effects on exercise-induced bronchoconstriction

Exercise-induced bronchoconstriction (EIB) is exaggerated constriction of the airways usually soon after cessation of exercise. This is most often a response to airway dehydration in the presence of airway inflammation in a person with a responsive bronchial smooth muscle. Severity is related to water content of inspired air and level of ventilation achieved and sustained. Repetitive hyperpnea of dry air during training is associated with airway inflammatory changes and remodeling. A response during exercise that is related to pollution or allergen is considered EIB. Ozone and particulate matter are the most widespread pollutants of concern for the exercising population; chronic exposure can lead to new-onset asthma and EIB. Freshly generated emissions particulate matter less than 100 nm is most harmful. Evidence for acute and long-term effects from exercise while inhaling high levels of ozone and/or particulate matter exists. Much evidence supports a relationship between development of airway disorders and exercise in the chlorinated pool. Swimmers typically do not respond in the pool; however, a large percentage responds to a dry air exercise challenge. Studies support oxidative stress mediated pathology for pollutants and a more severe acute response occurs in the asthmatic. Winter sport athletes and swimmers have a higher prevalence of EIB, asthma and airway remodeling than other athletes and the general population. Because of fossil fuel powered ice resurfacers in ice rinks, ice rink athletes have shown high rates of EIB and asthma. For the athlete training in the urban environment, training during low traffic hours and in low traffic areas is suggested.

Temperature effects on outpatient visits of respiratory diseases, asthma, and chronic airway obstruction in Taiwan

This study evaluated the risk of outpatient visits for respiratory diseases, asthma, and chronic airway obstruction not elsewhere classified (CAO) associated with ambient temperatures and extreme temperature events from 2000 to 2008 in Taiwan. Based on geographical and socioeconomics characteristics, this study divided the whole island into seven areas. A distributed lag non-linear model was used to estimate the area-disease-specific cumulative relative risk (RR), and random-effect meta-analysis was used to estimate the pooled RR of outpatient visits, from lag 0 to lag 7 days, associated with daily temperature, and added effects of prolonged extreme heat and cold for population of all ages, the elderly and younger than 65 years. Pooled analyses showed that younger population had higher outpatient visits for exposing to low temperature of 18 °C, with cumulative 8-day RRs of 1.36 (95% confidence interval (CI) 1.31-1.42) for respiratory diseases, 1.10 (95% CI 1.03-1.18) for asthma, and 1.12 (95% CI 1.02-1.22) for CAO. The elderly was more vulnerable to high temperature of 30 °C with the cumulative 8-day RR of 1.08 (95% CI 1.03-1.13) for CAO. Elevated outpatient visits for all respiratory diseases and asthma were associated with extreme heat lasting for 6 to 8 days. On the contrary, the extreme cold lasting more than 8 days had significant negative association with outpatient visits of all respiratory diseases. In summary, elderly patients of respiratory diseases and CAO are vulnerable to high temperature. Cold temperature is associated with all types of respiratory diseases for younger patients.

Vitamin E and D regulation of allergic asthma immunopathogenesis

Asthma occurs as complex interactions of the environmental and genetics. Clinical studies and animal models of asthma indicate dietary factors such as vitamin E and vitamin D as protective for asthma risk. In this review, we discuss opposing regulatory functions of tocopherol isoforms of vitamin E and regulatory functions of vitamin D in asthma and how the variation in global prevalence of asthma may be explained, at least in part, by these dietary components.

Fine particulate matter, temperature, and lung function in healthy adults: findings from the HVNR study

Both ambient particulate air pollution and temperature alterations have been associated with adverse human health effects, but the interactive effect of ambient particulate and temperature on human health remains uncertain. The present study investigated the effects of ambient particulate matter with an aerodynamic diameter⩽2.5 μm (PM2.5) and temperature on human lung function simultaneously in a panel of 21 healthy university students from the Healthy Volunteer Natural Relocation (HVNR) study in the context of suburban/urban air pollution in Beijing, China. Each study subject used an electronic diary meter to record peak expiratory flow (PEF) and forced expiratory volume in 1s (FEV1) twice a day for 6 months in three periods before and after relocating from a suburban area to an urban area with changing ambient PM2.5 and temperature levels in Beijing. Hourly-averaged environmental data were obtained from central air-monitoring sites. Exposure effects were estimated using generalized linear mixed models controlling for potential confounders. Study subjects provided 6494 daily measurements on PEF and 6460 daily measurements on FEV1 over the study. PM2.5 was associated with reductions in evening PEF and morning/evening FEV1 whereas temperature was associated with reductions in morning PEF. The estimated PM2.5 effects on evening PEF and morning/evening FEV1 in the presence of high temperature were generally stronger than those in the presence of low temperature, and the estimated temperature effects on morning/evening PEF and morning FEV1 in the presence of high PM2.5 were also generally stronger than those in the presence of low PM2.5. For example, there were a 2.47% (95% confidence interval: -4.24, -0.69) reduction and a 0.78% (95% confidence interval: -1.59, 0.03) reduction in evening PEF associated with an interquartile range increase (78.7 μg/m(3)) in PM2.5 at 4-d moving average in the presence of high temperature (⩾21.6 °C) and low temperature (<21.6 °C), respectively. Our findings suggest that ambient particulate and temperature may interact synergistically to cause adverse respiratory health effects.

The vitamin E isoforms α-tocopherol and γ-tocopherol have opposite associations with spirometric parameters: the CARDIA study

Background

Clinical studies of the associations of vitamin E with lung function have reported conflicting results. However, these reports primarily examine the α-tocopherol isoform of vitamin E and have not included the isoform γ-tocopherol which we recently demonstrated in vitro opposes the function of α-tocopherol. We previously demonstrated, in vitro and in animal studies, that the vitamin E isoform α-tocopherol protects, but the isoform γ-tocopherol promotes lung inflammation and airway hyperresponsiveness.

Methods

To translate these findings to humans, we conducted analysis of 4526 adults in the Coronary Artery Risk Development in Young Adults (CARDIA) multi-center cohort with available spirometry and tocopherol data in blacks and whites. Spirometry was obtained at years 0, 5, 10, and 20 and serum tocopherol was from years 0, 7 and 15 of CARDIA.

Results

In cross-sectional regression analysis at year 0, higher γ-tocopherol associated with lower FEV₁ (p = 0.03 in blacks and p = 0.01 in all participants) and FVC (p = 0.01 in blacks, p = 0.05 in whites, and p = 0.005 in all participants), whereas higher α-tocopherol associated with higher FVC (p = 0.04 in blacks and whites and p = 0.01 in all participants). In the lowest quartile of α-tocopherol, higher γ-tocopherol associated with a lower FEV₁ (p = 0.05 in blacks and p = 0.02 in all participants). In contrast, in the lowest quartile of γ-tocopherol, higher α-tocopherol associated with a higher FEV₁ (p = 0.03) in blacks. Serum γ-tocopherol >10 μM was associated with a 175–545 ml lower FEV₁ and FVC at ages 21–55 years.

Conclusion

Increasing serum concentrations of γ-tocopherol were associated with lower FEV1 or FVC, whereas increasing serum concentrations of α-tocopherol was associated with higher FEV1 or FVC. Based on the prevalence of serum γ-tocopherol >10 μM in adults in CARDIA and the adult U.S. population in the 2011 census, we expect that the lower FEV₁ and FVC at these concentrations of serum γ-tocopherol occur in up to 4.5 million adults in the population.

Asthma and allergic rhinitis increase respiratory symptoms in cold weather among young adults

BACKGROUND

The occurrence of cold temperature-related symptoms has not been investigated previously in young adults, although cold weather may provoke severe symptoms leading to activity limitations, and those with pre-existing respiratory conditions may form a susceptible group. We tested the hypothesis that young adults with asthma and allergic rhinitis experience cold-related respiratory symptoms more commonly than young adults in general.

METHODS

A population-based study of 1623 subjects 20-27 years old was conducted with a questionnaire inquiring about cold weather-related respiratory symptoms, doctor-diagnosed asthma and rhinitis, and lifestyle and environmental exposures.

RESULTS

Current asthma increased the risk of all cold weather-related symptoms (shortness of breath adjusted PR 4.53, 95% confidence interval 2.93-6.99, wheezing 10.70, 5.38-21.29, phlegm production 2.51, 1.37-4.62, cough 3.41, 1.97-5.87 and chest pain 2.53, 0.82-7.79). Allergic rhinitis had additional effect especially on shortness of breath (7.16, 5.30-9.67) and wheezing (13.05, 7.75-22.00), some on phlegm production (3.69, 2.49-5.47), but marginal effect on cough and chest pain.

INTERPRETATION

Our study shows that already in young adulthood those with asthma, and especially those with coexisting allergic rhinitis, experience substantially more cold temperature-related respiratory symptoms than healthy young adults. Hence, young adults with a respiratory disease form a susceptible group that needs special care and guidance for coping with cold weather.

Assessment of EIB: What you need to know to optimize test results

Respiratory symptoms and asthma control questionnaires are poor predictors of the presence or severity of exercise-induced bronchoconstriction (EIB), and objective measurement is recommended. To optimize the chance of a positive test result, there are several factors to consider when exercising patients for EIB, including the ventilation achieved and sustained during exercise, water content of the inspired air, and the natural variability of the response. The high rate of negative exercise test results has led to the development of surrogates to identify EIB in laboratory or office settings, including eucapnic voluntary hyperpnea of dry air and inhalation of hyperosmolar aerosols.

Exercise capacity and exercise-induced bronchoconstriction (EIB) in a cold environment

INTRODUCTION

Exercise in a cold environment has been reported to increase exercise-induced bronchoconstriction (EIB). However, the effect of a cold environment upon exercise capacity in subjects with EIB has, to our knowledge, not been previously reported.

PURPOSE

Primary: To examine the influence of changing environmental temperature upon exercise capacity measured by peak oxygen uptake (VO(2 peak)), peak ventilation (VE(peak)) and peak running speed in subjects with diagnosed EIB. Secondary: To assess the influence of changing environmental temperature upon EIB.

METHODS

Twenty subjects (10-45 years old, male/female: 13/7) with EIB underwent exercise testing by running on a treadmill in a climate chamber under standardised, regular conditions, 20.2 degrees C (+/-1.1) and 40.0% (+/-3.3) relative humidity [mean(+/-SD)], and in a standardised cold environment, -18.0 degrees C (+/-1.4) and 39.2% (+/-3.8) relative humidity in random order on separate days. Oxygen uptake (VO(2)), minute ventilation (V E), respiratory exchange ratio (RER), heart rate (HR) and running speed were measured during exercise. Lung function (flow volume loops) was measured before and 1, 3, 6, 10 and 15 min after exercise and 15 min after inhalation of salbutamol.

RESULTS

VO(2 peak) decreased 6.5%, from 47.9 (45.0, 50.8) to 44.8 ml kg(-1)min(-1) (41.2, 48.4) [mean (95% confidence intervals)] (p=0.004) in the cold environment. Also running speed was significantly lower in the cold environment (p=0.02). No differences were found for VE(peak), RER(peak) or HR(peak). The post-exercise reduction in forced expiratory volume in 1s (FEV(1)) (DeltaFEV(1)) increased significantly from 24% (19,29) to 31% (24,38), respectively (p=0.04) after exercise in the cold environment. No correlation was found between reduction in VO(2 peak) and the increased maximum fall in FEV(1) in the cold environment.

CONCLUSION

Exercise capacity (VO(2 peak) and peak running speed) was markedly reduced during exercise in a cold environment whereas EIB increased in subjects suffering from EIB.

Asthma, airway inflammation and treatment in elite athletes

Highly trained athletes are repeatedly and strongly exposed to cold air during winter training and to many inhalant irritants and allergens all year round. Asthma occurs most commonly in athletes engaging in endurance events such as cross-country skiing, swimming, or long-distance running. As well as the type of training, a major risk factor is atopic disposition. A mixed type of eosinophilic and neutrophilic airway inflammation has been shown to affect elite swimmers, ice-hockey players, and cross-country skiers. The inflammation may represent a form of repeated thermal, mechanical, or osmotic airway trauma resulting in a healing or remodelling process. Elite athletes commonly use antiasthma drugs to treat exercise-induced bronchial symptoms. Only a few controlled studies have been conducted on the effects of antiasthma drugs on asthma symptoms, bronchial hyperresponsiveness and airway inflammation in elite athletes. Inhaled beta(2)-adrenoceptor agonists are effective against exercise-induced bronchospasm. In contrast, airway inflammation, bronchial hyperresponsiveness and symptoms have responded poorly to inhaled corticosteroids and leukotriene antagonists. As discontinuing high-level exercise has proved effective in reducing eosinophilic airway inflammation, exercise or training should be restricted in athletes having troublesome symptoms and sputum eosinophilia. Switching training to less irritating environments should be considered whenever possible. It appears to be difficult to change the 'natural course' of asthma in athletes by anti-inflammatory treatment.

Influence of low temperature on bronchodilatation induced by terbutaline administered by metered dose or dry powder inhalers in asthmatics

Low temperatures may affect dose delivery efficacy and clinical effectiveness of medication aerosols. In this study we examine the effect of cold ambient temperature on the bronchodilatation produced by terbutaline delivered from a chlorofluorocarbon pressurized metered dose inhaler (pMDI) compared to a multi-dose dry powder inhaler (DPI). Fourteen stable asthmatics were studied on two consecutive days. On day 1, after measuring FEV1 at room temperature (22 degrees C), each patient was randomized to receive 500 microg of terbutaline delivered from pMDI or DPI stored for 24 h at 22 degrees C with FEV1 recorded 20 min post-dose; then, patients were placed in a chamber at -10 degrees C, and after obtaining FEV1, each patient received 500 microg of terbutaline delivered from pMDI or DPI (same formulation as previously administered) stored for 24 h at -10 degrees C, and FEV1 was obtained 20 min post-dose. On day 2, a similar protocol was followed but each patient received terbutaline as the alternative to the formulation administered on day 1. Pairwise comparisons of the FEV1 (% predicted) values obtained on day 1 and day 2 at 22 degrees C and -10 degrees C (pre-dose) showed no significant differences. Similar bronchodilatations were observed for terbutaline DPI administration at 22 degrees C and -10 degrees C (24.85 +/- 11.72 and 20.08 +/- 6.27% increase of FEV1; P > 0.05). By contrast, the bronchodilatation obtained for terbutaline pMDI at 22 degrees C (21.07 +/- 8.55% increase in FEV1) was not reproduced at -10 degrees C (0.72 +/- 2.84%; P < 0.05 from 22 degrees C). In five asthmatics a cumulative dose-response curve for terbutaline pMDI was obtained. This part of the study showed that a higher dose of terbutaline pMDI was necessary at -10 degrees C to obtain a bronchodilator response (10.04 +/- 6.75% increase of FEV1 after 2,000 microg) that remained lower than the bronchodilatation for 500 microg terbutaline pMDI at -10 degrees C. In conclusion, the clinical effectiveness of terbutaline delivered from chlorofluorocarbon pMDIs is compromised by cold storage while DPIs are not affected.

Asthma and allergy among schoolchildren in a mountainous, dry, non-polluted area in Norway

The aim of this study was to assess prevalence of asthma and allergy in the non-polluted mountain area of Upper Hallingdal, Norway. All schoolchildren (7-16 years) who in a previous questionnaire survey (n = 1177) reported 'sometime' asthma were enrolled in group I (n = 80), the 59 who reported asthma-like symptoms in the past 12 months formed group II, and 77 of the healthy controls were randomly selected as group III. All 216 children underwent clinical examination, skin prick test, spirometry, bronchial provocation (PD20 metacholine) and treadmill exercise test. Subsequently they were reclassified as (1) healthy, never had asthma or symptoms, (2) symptoms not confirmed as asthma, (3) previous asthma, now healthy, (4) current asthma. Lifetime asthma prevalence was 10.2%. Based upon clinical examination, the specificity and sensitivity of the questionnaire for asthma diagnosis were 88 and 74%, respectively. Forced vital capacity was significantly higher among the asthmatics (group 4 versus 1), whereas forced expiratory volume in one second (FEV1) and forced expiratory flow at 50% of vital capacity were similar in all groups. More than 10% reduction in FEV1 following treadmill-run was found in 20% of children. Children with current asthma compared to controls had significantly; lower mean values of PD20 (9.1 versus 16.5 micromol), higher eosinophil cationic protein (13.4 versus 7.7 micromol) and more frequent sensitization to animal dander (56% versus 10%). In conclusion, despite a favorable climate, little mite sensitization and low outdoor pollution, asthma prevalence was surprisingly high in Upper Hallingdal. Sensitization to animal dander was the most important contributing factor for current asthma.

Influence of Storage at Low Temperatures on the Aerosol Output from Metered-Dose and Dry-Powder Inhalation Devices

Objective:

To determine whether storage at low temperatures affects the drug delivery efficacy of a chlorofluorocarbon (CFC)-free aerosol and a dry-powder inhaler (DPI).

Design:

Aerosol output from a CFC-free hydrofluoroalkane (HFA-134a) metered-dose inhaler (albuterol) and a multidose DPI (terbutaline) were examined at different ambient temperatures and canister loads.

Results:

After the HFA-134a formulation was stored at low temperatures for 24 hours, a small decrease of aerosol output (2.1–2.7% at 0 °C, 5.0–8.0% at −10 °C; p < 0.05 from 22 °C) was observed. In addition, the aerosol output from devices with one-half or one-fifth the initial content was marginally decreased compared with output from inhalers with full content. Image analysis techniques applied to fully formed aerosol plume emitted from the HFA-134a formulation showed that the product could still be aerosolized at 10 °C, but there was a reduction of the distance reached by the aerosol. In contrast, condensed droplets markedly altered the aerosols formed from CFC inhalers at −10 °C. Aerosol output from the DPI apparently was not altered following 24-hour storage at −10 °C.

Conclusions:

Aerosols emitted by the HFA-134a and DPIs studied were less affected by exposure to cold temperatures compared with those from marketed CFC devices.

Exercise-induced bronchoconstriction in adults with asthma--comparison between running and cycling and between cycling at different air conditions

The bronchial response to cycling and running was compared in six adult asthmatic persons. The effects of different air conditions during cycling regarding the induction of bronchoconstriction was studied. The exercise consisted of 6 minutes' work at an intensity of 80-85% of maximal heart rate. Heart rate, oxygen consumption and ventilation were measured to check that the exercise level was the same in all tests. Peak expiratory flow (PEF) was used to test for bronchoconstriction. Bicycling and treadmill running were performed under indoor conditions and bicycling while breathing cold, dry air (-18 degrees C) and room-tempered humid air (60% RH), respectively. No difference in bronchoconstriction was found between cycling and running under indoor conditions. However, bicycling exercise with inhalation of cold dry air provoked more bronchoconstriction than when inhalating humid air (PEF reductions of 19.4+/-6% and 6.1+/-2%, respectively). No differences were found between the exercise modes in heart rate, oxygen consumption, ventilation per minute, respiratory rate, carbon dioxide elimination or subjective ratings of perceived exertion and breathlessness. It is concluded that it is not the type of exercise, but the ventilation demand and humidity of the inspired air that are the main determinants of the occurrence and degree of bronchoconstriction.

How Pollution and Airborne Allergens Affect Exercise

In brief Air pollution, airborne allergens, and changing weather conditions-alone or in combination-can hinder physical activity. In any active individual, high ozone levels can cause restrictive lung dysfunction, and high carbon monoxide levels can impair oxygen delivery. Sulfur dioxide worsens nasal symptoms in people who have allergies and causes bronchospasm in those who have asthma. Airway irritation from fine particulates can lead to bronchospasm. Atopic individuals suffer from the well-known effects of fungi and pollen. If a change in exercise routine or activity doesn't relieve symptoms, pharmacologic treatment may include antihistamines, immunotherapy, inhaled corticosteroids, and/or inhaled beta-₂ bronchodilators.