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Background: Allergic disease is a recognized global epidemic and a significant cause of ill health and poor quality of life. The prevalence of pollen allergy is high throughout the world, and pollen exposure itself plays a role in emergency department presentations and hospitalizations for asthma. Lung function and airway inflammation are important measures of asthma activity and control., Objective: To examine associations between exposure to multiple pollen types and lung function and markers of airway inflammation at 8 and 14 years of age, and to explore potential modification by residential greenness., Methods: A cohort of high-risk children living in Sydney, Australia had spirometry and fractional exhaled nitric oxide (FeNO) measured at 8 and 14 years of age. Ambient pollen concentration on the day of lung function measurement and up to three days prior was used as the exposure measure. Residential greenness was derived from satellite imagery. We modelled the association between six pollen types and lung function and FeNO. We also assessed modifying effects of residential greenness., Results: Casuarina, cypress and Pinus pollen in the air the day before measurement and 3 days prior respectively, were associated with reduced lung function in 8-year-olds. The pollen exposures were associated with decreases in FEV 1 and FVC; however, the FEV 1 /FVC ratio was not affected. Effect modification by greenness was not observed due to loss of power., Conclusions & Clinical Relevance: Airborne tree pollen of cypress, Casuarina and Pinus and not grass in some regions may be detrimental to childhood lung function., (© 2020 John Wiley & Sons Ltd.)

Background: Studies of potential adverse effects of traffic related air pollution (TRAP) on allergic disease have had mixed findings. Nutritional studies to examine whether fish oil supplementation may protect against development of allergic disease through their anti-inflammatory actions have also had mixed findings. Extremely few studies to date have considered whether air pollution and dietary factors such as fish oil intake may interact, which was the rationale for this study., Methods: We conducted a secondary analysis of the Childhood Asthma Prevention Study (CAPS) birth cohort, where children were randomised to fish oil supplementation or placebo from early life to age 5 years. We examined interactions between supplementation and TRAP (using weighted road density at place of residence as our measure of traffic related air pollution exposure) with allergic disease and lung function outcomes at age 5 and 8 years., Results: Outcome information was available on approximately 400 children (~ 70% of the original birth cohort). Statistically significant interactions between fish oil supplementation and TRAP were seen for house dust mite (HDM), inhalant and all-allergen skin prick tests (SPTs) and for HDM-specific interleukin-5 response at age 5. Adjusting for relevant confounders, relative risks (RRs) for positive HDM SPT were RR 1.74 (95% CI 1.22-2.48) per 100 m local road or 33.3 m of motorway within 50 m of the home for those randomised to the control group and 1.03 (0.76-1.41) for those randomised to receive the fish oil supplement. The risk differential was highest in an analysis restricted to those who did not change address between ages 5 and 8 years. In this sub-group, supplementation also protected against the effect of traffic exposure on pre-bronchodilator FEV 1 /FVC ratio., Conclusions: Results suggest that fish oil supplementation may protect against pro-allergic sensitisation effects of TRAP exposure. Strengths of this analysis are that supplementation was randomised and independent of TRAP exposure, however, findings need to be confirmed in a larger experimental study with the interaction investigated as a primary hypothesis, potentially also exploring epigenetic mechanisms. More generally, studies of adverse health effects of air pollution may benefit from considering potential effect modification by diet and other factors., Trial Registration: Australia New Zealand Clinical Trial Registry. www.anzctr.org.au Registration: ACTRN12605000042640 , Date: 26th July 2005. Retrospectively registered, trial commenced prior to registry availability.

Background: There are long-standing concerns about adverse effects of gas appliances on respiratory health. However, the potential adverse effect of low-NOx (nitrogen oxide) unflued gas heaters on children's health has not been assessed., Objectives: Our goal was to compare the respiratory health effects and air quality consequences of exposure to low-NOx unflued gas heaters with exposure to non-indoor-air-emitting flued gas heaters in school classrooms., Methods: We conducted a double-blind, cluster-randomized, crossover study in 400 primary school students attending 22 schools in New South Wales, Australia. Children measured their lung function and recorded symptoms and medication use twice daily. Nitrogen dioxide (NO2) and formaldehyde concentrations were measured in classrooms using passive diffusion badges., Results: NO2 concentrations were, on average, 1.8 times higher [95% confidence interval (CI), 1.6-2.1] and formaldehyde concentrations were, on average, 9.4 ppb higher (95% CI, 5.7-13.1) during exposure to unflued gas versus flued gas heaters. Exposure to the unflued gas heaters was associated with increased cough reported in the evening [odds ratio (OR) = 1.16; 95% CI, 1.01-1.34] and wheeze reported in the morning (OR = 1.38; 95% CI, 1.04-1.83). The association with wheeze was greater in atopic subjects. There was no evidence of an adverse effect on lung function., Conclusions: We conclude that classroom exposure to low-NOx unflued gas heaters causes increased respiratory symptoms, particularly in atopic children, but is not associated with significant decrements in lung function. It is important to seek alternative sources of heating that do not have adverse effects on health.

Background: The proportion of asthma in adults that is due to occupational exposures is not known., Aim: To examine the contribution of workplace exposures to the development of asthma in adults in New South Wales (NSW) in a cross sectional, population-based study., Methods: A randomly selected population of 5,331 18- to 49-year olds completed and returned a mailed questionnaire (response rate 37%). In adult-onset asthmatics we examined the association of asthma with reported exposure, within 1 year of asthma onset, to a list of occupations and exposures known to be at risk for occupational asthma (high-risk jobs and exposures)., Results: Among 910 subjects (18%) with asthma, 383 (7%) subjects reported adult-onset disease. After adjusting for sex, age and smoking, working in any high-risk job or exposure at the time of asthma onset was significantly associated with adult-onset asthma (OR 1.51, 95% CI 1.19-1.92). The population attributable risk (PAR) of adult-onset asthma for either a high-risk job or an exposure was 9.5%. Sudden onset, irritant or reactive airways dysfunction syndrome type exposures were associated with adult-onset asthma (OR 4.65, 95% CI 1.64-13.2). The PAR of adult-onset asthma for these exposures was 0.2%., Conclusion: Reported adult onset of asthma is common and occupational exposures may be associated with 9.5% of prevalent cases of adult-onset asthma in NSW.

Background: Asthma and allergic sensitization to cats frequently coexist, although recent studies show less atopic disease among people who had pets in infancy. However, no longterm evaluations have been performed thus far., Objective: We sought to evaluate the relationship between cat ownership at different age periods (< 18, > 18, and both periods and atopic disease at age 28., Methods: Australian school children aged 8 to 10 years were recruited in 1982 and participated in follow-up surveys until 2002. Cat ownership was defined by surveys in 1992 and 2002 as having a cat before age 18 only, after age 18 only, or in both periods of life. Health outcomes were defined at a mean age of 28.5 years., Results: Complete data were available for 224 subjects, 50 of whom had a cat before 18 years of age only, 14 after age 18 only, and 70 in both periods. Compared with 90 subjects that never had a cat, having a cat before age 18 protected against atopy to outdoor allergens, airway hyperresponsiveness (AHR) to histamine, current wheeze, and current asthma (P < .05). In contrast, subjects who acquired their first cat after age 18 showed a trend toward higher prevalence rates for asthma symptoms and AHR (P > .10)., Conclusions: Having had a cat before 18 years of age protects against adult asthma and atopy.

To evaluate the association between growth in height and growth in lung function, and to identify the potential temporal relationships between airway hyperresponsiveness (AHR), respiratory symptoms, and lung function growth during adolescence and young adulthood, we analyzed data collected from the Belmont cohort. Among the 718 schoolchildren initially studied at 1982 (aged 8-10 yr), 557 were studied between two times and six times at 2-yr intervals until 1992. Baseline lung function, AHR by histamine inhalation test, and recent wheeze by questionnaires, were measured at each visit. We found that between 17 and 19 yr of age, when growth in height had stopped, growth in FEV(1) was approximately 200 ml/yr in boys and 100 ml/yr in girls. Peak growth velocity of height occurred at age 13 both in boys and in girls, whereas peak growth velocity of FEV(1) occurred at the same age only in girls and 1 yr later in boys. Having AHR and recent wheeze at the previous study time were both associated with lower subsequent growth in FEV(1), but not with subsequent growth in FVC. We conclude that lung function continues to grow after the cessation of height growth and that growth in FEV(1) is reduced in subjects with AHR and/or recent wheeze.

Background and Aims: To assess accurately the effect of parental smoking on the respiratory health of New South Wales (NSW) school children, we obtained a large data set by pooling data from seven cross-sectional studies conducted in NSW between 1991 and 1993., Methods: A random sample of 6394 children age eight to 11 years was studied. Respiratory symptoms, family history of asthma and parental smoking history were measured by questionnaire, atopy by skin prick test and airway hyper-responsiveness (AHR) by histamine inhalation test., Results: In total, 58.3% of children had at least one parent who smoked; 38.5% were exposed to maternal smoking. After adjusting for potential confounders, such as atopy, parental history of asthma and bronchitis in the first two years, children who were exposed to maternal smoking had a significantly increased risk of recent wheeze but not of AHR (odds ratios 1.33; 95% CI: 1.2-1.5 and 1.00; 95% CI: 0.9-1.2)., Conclusions: The positive association with wheeze and the lack of an association with AHR suggests that exposure to parental smoking leads to wheezing, but does not increase airway responsiveness.

Objective: To compare the prevalence and severity of asthma and of allergic sensitisation in children in different regions. We hypothesised that regions with different standardised hospital admission rates would have different prevalences of childhood asthma and that diverse climates would result in a range of sensitisations to different allergens., Design and Setting: We studied large random population samples of children in seven regions in New South Wales (NSW) in 1991-1993. Hospitalisation rates were obtained from NSW Department of Health data., Participants: 6394 children aged 8-11 years., Outcome Measures: History of respiratory symptoms by self-administered questionnaire; airway hyperresponsiveness by histamine inhalation test; and sensitisation to allergens by skin-prick tests., Results: Children in all regions had a high prevalence of recent wheeze (22%-27%), of diagnosed asthma (24%-38%) and of use of asthma medications (22%-30%), but no region was consistently higher or lower for all measurements. The prevalence of current asthma in children living in three coastal regions (where sensitisation to house-dust mites was high) and in the far west (where sensitisation to alternaria was high) was 12%-13%, which was significantly higher than the prevalence of 7%-10% in children living in three inland regions (where sensitisation to these allergens was lower) (P < 0.01)., Conclusions: We found significant variations in the prevalence and severity of childhood asthma in NSW. The prevalence of hospitalisations, diagnosed asthma, recent symptoms and medication use may relate to different regional diagnostic patterns, whereas current asthma prevalence may relate to different levels of allergic sensitisation.

We wanted to examine the predictive nature, over one year, of bronchial hyperresponsiveness (BHR) and recent wheeze (in the previous 12 months), which are the measurements frequently used to classify asthma for epidemiology. A prospective cohort study of 236 children, aged 8-11 yrs, was undertaken, with an initial baseline study, followed by four studies at three monthly intervals over one year. At each study, we measured bronchial responsiveness to histamine by the rapid method, respiratory symptoms by parent questionnaire, and atopy by skin prick tests to common allergens. Airflometer readings, which are closely related to FEV1, were self-recorded. Baseline data were used to classify children into the four categories of "current asthma" (BHR and wheeze), "wheeze only", "BHR only", or "normal". During the year following baseline study, the group initially classified as "wheeze only" had normal Airflometer variability, and 59% had wheeze, and 33% had BHR, which tended to be mild. In the group initially classified as "BHR only", 52% had wheeze with a peak in winter, and 62% had BHR during the following year. This group had more severe bronchial responsiveness and Airflometer variability than the normal and wheeze only groups. The group initially classified as current asthma had a more severe condition, with continued BHR (100%), and wheeze (93%), increased Airflometer variability and more atopy. Thus, the natural history of bronchial responsiveness, respiratory symptoms and allergic history in this group was different from the other three groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Because there is no "gold standard" for defining asthma for epidemiology, we have defined current asthma as bronchial hyperresponsiveness (BHR) plus recent wheeze (in the 12 months prior to study). To describe the characteristics of groups categorized by these measurements, we studied two samples of children aged 7 to 12 yr: 210 from a population sample and 142 self-identified asthmatics. Bronchial responsiveness to histamine was measured by the rapid method, respiratory symptom history, and asthma medication use by self-administered questionnaire to parents and atopy by skin prick tests to 14 allergens. Children recorded daily Airflometer readings and symptom scores for 2 wk. Children with current asthma had more severe bronchial responsiveness, greater Airflometer variability, more symptoms, more atopy (particularly to house dust mites), and used more asthma medication than children with BHR or recent wheeze alone. Children with BHR, but not with recent wheeze, were intermediate between the current asthma and normal groups in terms of bronchial responsiveness, Airflometer variability, and atopy. Children with recent wheeze and normal responsiveness differed from the normal group only in symptoms and medication use. Our definition of current asthma discriminates a group of children that is clearly different in terms of both clinical features and physiologic measures. As such, it is the most useful definition to date for measuring the prevalence of clinically important asthma in populations.

To measure the repeatability of the bronchial challenge test and the comparability of histamine and methacholine as provoking agents, we studied a population sample of children and conducted histamine bronchial challenge tests on each of 3 consecutive days followed by a methacholine bronchial challenge on the fourth day. Bronchial responsiveness was measured using the rapid inhalation method. A total of 393 children had satisfactory bronchial challenge data for all 4 days. The measurements derived from the dose-response curve were the PD20 FEV1, which was measured as the provoking dose causing a 20% fall in FEV1, and the dose-response slope (DRS), which was measured as the percentage fall in FEV1 at final dose/total dose administered. Children who had a PD20 FEV1 were categorized as having bronchial hyperresponsiveness (BHR). The percentage of children with BHR each day was between 7 and 11. One-third of the children with BHR reacted only to histamine or methacholine. The within-subject range for histamine PD20 FEV1 values compared with methacholine suggested that histamine and methacholine are not directly comparable bronchial challenge agents. The dose-response slope values, which could be obtained for all children, had slightly better repeatability than PD20 FEV1 values. Because DRS values obtain data for the entire sample, have good repeatability, and are equally repeatable in children with normal responsiveness or bronchial hyperresponsiveness, they should prove more useful than PD20 FEV1 values for measuring bronchial responsiveness in populations.