The IVAIRE project--a randomized controlled study of the impact of ventilation on indoor air quality and the respiratory symptoms of asthmatic children in single family homes

A randomized controlled trial was carried out to measure the impact of an intervention on ventilation, indoor air contaminants, and asthma symptoms of children. Eighty-three asthmatic children living in low-ventilated homes were followed over 2 years. Several environmental parameters were measured during the summer, fall, and winter. The children were randomized after Year 1 (43 Intervention; 40 Control). The intervention included the installation of either a Heat Recovery Ventilator (HRV) or Energy Recovery Ventilator (ERV). During the fall and winter seasons, there was a significant increase in the mean ventilation rate in the homes of the intervention group. A statistically significant reduction in mean formaldehyde, airborne mold spores, toluene, styrene, limonene, and α-pinene concentrations was observed in the intervention group. There was no significant group difference in change in the number of days with symptoms per 14 days. However, there was a significant decrease in the proportion of children who experienced any wheezing (≥1 episode) and those with ≥4 episodes in the 12-month period in the intervention group. This study indicates that improved ventilation reduces air contaminants and may prevent wheezing. Due to lack of power, a bigger study is needed.

PRACTICAL IMPLICATIONS

Positive findings from this study include the fact that, upon recruitment, most of the single family homes with asthmatic children were already equipped with a mechanical ventilation system and had relatively good indoor air quality. However, the 8-h indoor guideline for formaldehyde (50 μg/m3) was frequently exceeded and the ventilation rates were low in most of the homes, even those with a ventilation system. Both ERVs and HRVs were equally effective at increasing air exchange rates above 0.30 ACH and at preventing formaldehyde concentrations from exceeding the 50 μg/m3 guideline during the fall and winter seasons. Furthermore, the ERVs were effective at preventing excessively low relative humidities in the homes. Based on observed difference of risk, intervention to increase ventilation in five sample homes and children would prevent 1 home to exceed the indoor air long-term formaldehyde guideline and prevent 1 asthmatic child experiencing at least one episode of wheezing over a year.

A cross-sectional study of shift work, sleep quality and cardiometabolic risk in female hospital employees

OBJECTIVES

Investigating the potential pathways linking shift work and cardiovascular diseases (CVD), this study aimed to identify whether sleep disturbances mediate the relationship between shift work and the metabolic syndrome, a cluster of CVD risk factors.

DESIGN

Cross-sectional study.

SETTING

A tertiary-level, acute care teaching hospital in Southeastern Ontario, Canada.

PARTICIPANTS

Female hospital employees working a shift schedule of two 12 h days, two 12 h nights, followed by 5 days off (n=121) were compared with female day-only workers (n=150).

PRIMARY AND SECONDARY OUTCOME MEASURES

Each of the seven components of the Pittsburgh Sleep Quality Index (PSQI) was measured. Of these, PSQI global score, sleep latency and sleep efficiency were examined as potential mediators in the relationship between shift work and the metabolic syndrome.

RESULTS

Shift work status was associated with poor (>5) PSQI global score (OR=2.10, 95% CI 1.20 to 3.65), poor (≥2) sleep latency (OR=2.18, 95% CI 1.23 to 3.87) and poor (≥2) sleep efficiency (OR=2.11, 95% CI 1.16 to 3.84). Although shift work was associated with the metabolic syndrome (OR=2.29, 95% CI 1.12 to 4.70), the measured components of sleep quality did not mediate the relationship between shift work and the metabolic syndrome.

CONCLUSIONS

Women working in a rapid forward rotating shift pattern have poorer sleep quality according to self-reported indicators of the validated PSQI and they have a higher prevalence of the metabolic syndrome compared with women who work during the day only. However, sleep quality did not mediate the relationship between shift work and the metabolic syndrome, suggesting that there are other psychophysiological pathways linking shift work to increased risk for CVD.

Regulation of raft-dependent endocytosis

Raft-dependent endocytosis is in large part defined as the cholesterol-sensitive, clathrin-independent internalization of ligands and receptors from the plasma membrane. It encompasses the endocytosis of caveolae, smooth plasmalemmal vesicles that form a subdomain of cholesterol and sphingolipid-rich lipid rafts and that are enriched for caveolin-1. While sharing common mechanisms, like cholesterol sensitivity, raft endocytic routes show differential regulation by various cellular components including caveolin-1, dynamin-2 and regulators of the actin cytoskeleton. Dynamin-dependent raft pathways, mediated by caveolae and morphologically equivalent non-caveolin vesicular intermediates, are referred to as caveolae/raft-dependent endocytosis. In contrast, dynamin-independent raft pathways are mediated by non-caveolar intermediates. Raft-dependent endocytosis is regulated by tyrosine kinase inhibitors and, through the regulation of the internalization of various ligands, receptors and effectors, is also a determinant of cellular signaling. In this review, we characterize and discuss the regulation of raft-dependent endocytic pathways and the role of key regulators such as caveolin-1.

[1998 Quebec Social and Health Survey: determinants of chronic respiratory diseases]

In the course of the "1998 Health and Social Survey", questions were included to verify the prevalence of chronic respiratory diseases and also of wheezing. The objectives of this study were 1) to verify the prevalence of wheezing and its validity as an indicator of chronic respiratory diseases in Québec; and 2) to examine the relationship between chronic respiratory diseases and some of their potential determinants. A total of 30,386 individuals participated in the study. For all ages, the prevalence of wheezing was 5.4%. It was associated with asthma, allergies, chronic bronchitis and emphysema. A low familial income and tobacco smoking were associated with wheezing, asthma, chronic bronchitis and emphysema. Passive smoking was associated with wheezing whereas the presence of carpets was associated with wheezing and asthma. Between 32 and 48% of families with an asthmatic or an allergic member modified their dwelling to alleviate respiratory problems. The prevalence of wheezing documented here was lower than in anglosaxon countries. This result could be explained by a cultural factor (the French translation or the perception of wheezing). This study emphasizes the role of reducing tobacco smoking in the prevention of chronic respiratory diseases.

Radon in residences: influences of geological and housing characteristics

222Rn is a radioactive gas emitted during the decay of 238U. 222Rn is a recognized lung carcinogen in humans and a common indoor air contaminant. This paper describes the results of research undertaken in 894 residences of the Province of Quebec (Canada), in which one of the objectives was to evaluate the influence of geological and housing characteristics on 222Rn levels. After a random selection of homes, 222Rn concentrations were measured with alpha track detectors in the basement and the main bedroom during two consecutive 6-mo periods. Geological subsoil characteristics were determined from various sources (e.g., geological maps, databanks on uranium sampling in lake and stream sediments), and housing characteristics were documented with a questionnaire. Statistical variance analysis of data indicates that geological factors only explain 5% and 4.5% of the variations in 222Rn concentrations, respectively, in the basement and on the first floor. When variables relative to housing characteristics are added, the analysis explains only 18% and 15% of the variations in 222Rn concentrations in the basement and on the first floor. These results illustrate the difficulties in predicting 222Rn concentrations in homes.

Characteristics of subjects with a high frequency of emergency visits for asthma

The determinants of frequent visits to the emergency department (ED) for asthma were evaluated in 30 patients who made 2 or more ED visits for asthma (mean, 3.1; range, 2 to 9) over a period of 1 year. They were matched for age, sex, and medication with a control group of asthmatic patients who had made no ED visits within the same period. Evaluation included measurements of expiratory flows (baseline FEV1; PEFR 4 times daily for 3 weeks), airway responsiveness to methacholine, perception of induced bronchoconstriction, and questionnaires on quality of life and knowledge of asthma and its management. In comparison with the control group, the study group showed a trend toward inferior socioeconomic status, education level, and technical abilities (eg, inhaler use). Both groups had similar baseline FEV1, reversibility of airflow obstruction, methacholine-induced changes in expiratory flows, and perception of bronchoconstriction. Diurnal variation in PEFR was slightly increased in the study group. Absenteeism from work or school was higher in the study group but quality of life score was similar to controls. Patients with frequent ED visits showed significantly lesser knowledge of asthma control criteria, as well as an overall trend toward reduced asthma management knowledge and skills. In conclusion, in addition to the previously reported undertreatment of asthma, other factors such as insufficient asthma management knowledge and skills may contribute to frequent ED visits for asthma.

[Pesticides and cancer in a Quebec rural farming population: a geographical interpretation]

Data on the use of pesticides in agriculture and three types of cancer among the rural farm population were compiled for 34 drainage basins of the province of Québec for 1982 and 1983. The basins were divided following three categories of exposure (low, intermediate, high) on the basis of the level of pesticides sales. Results at the scale of the three categories show that among women living in rural farm areas, the relative risk (RR) for cancers of the lymphatic tissues is of 1.62 when highly exposed basins were compared to low exposed basins (95% Confidence Interval = 1.16; 2.25), and of 1.63 (95% CI = 1.08; 2.45) when they were compared to basins with intermediate exposure. For women of 35-64 age group, RR values are respectively of 3.15 (95% CI = 1.67; 5.93) in the first case, and 3.73 (95% CI = 1.54; 9.01) in the second case. By another way, at the level of the 34 drainage basins, correlation analysis have shown statistically significant positive associations between several variables representing pesticides utilization in agriculture and geographic variations of some cancers, according to sex and age groups, especially for the following: men, cancer of the brain (1-14 and 15-34 age groups), cancers of the lymphatic tissues (34-64) and leukaemia (1-14); for women, cancer of the brain (35-64), the lymphatic tissues (35-64, 65 and more, all ages) and leukaemia (15-34, 35-64, 65 and more and all ages). After that, principal components analysis has been performed using variables representing pesticides utilization and socio-economic status by basin. Height factors have been produced, including two socio-economic and six pesticides-factors. Factor scores have been introduced in multiple regression analysis to see the role of each factor in the explanation of spatial distribution of those cancers who had been identified in the correlation analysis before. Results have shown that in most of the cases, only pesticides-factors have significant relationship with those cancers. Socio-economic factors play a significant role only for the following cancers: men, lymphatic tissues, 65 years old and more; women, cancer of the brain all ages, leukaemia 1-14 and 65 years old and more. However, these results must be interpreted with caution for the goal of the study is to describe potential relationships.(ABSTRACT TRUNCATED AT 400 WORDS)