Niina Jaakkola

Home dampness and molds, parental atopy, and asthma in childhood: a six-year population-based cohort study

Previous studies of how parental atopy and exposure to dampness and molds contribute to the risk of asthma have been mainly cross-sectional or prevalent case–control studies, where selection and information bias and temporality constitute problems. We assessed longitudinally the independent and joint effects of parental atopy and exposure to molds in dwellings on the development of asthma in childhood. We conducted a population-based, 6-year prospective cohort study of 1,984 children 1–7 years of age at the baseline in 1991 (follow-up rate, 77%). The study population included 1,916 children without asthma at baseline and complete outcome information. The data collection included a baseline and follow-up survey. The outcome of interest was development of asthma during the study period. The studied determinants were parental allergic diseases and four indicators of exposure at baseline: histories of water damage, presence of moisture and visible molds, and perceived mold odor in the home. A total of 138 (7.2%) children developed asthma during the study period, resulting in an incidence rate of 125 cases per 10,000 person-years [95% confidence interval (CI), 104–146]. In Poisson regression adjusting for confounding, parental atopy [adjusted incidence rate ratio (IRR) 1.52; 95% CI, 1.08–2.13] and the presence of mold odor in the home reported at baseline (adjusted IRR 2.44; 95% CI, 1.07–5.60) were independent determinants of asthma incidence, but no apparent interaction was observed. The results of this cohort study with assessment of exposure before the onset of asthma strengthen the evidence on the independent effects of parental atopy and exposure to molds on the development of asthma.

Smoking and asthma in adults

Studies on the effect of smoking on adulthood asthma have provided contradictory results. The current authors conducted a population-based incident case-control study to assess the effects of current and past smoking on the development of asthma in adults. During a 2.5 yr study period, all new asthma cases clinically diagnosed (n=521) and randomly selected controls (n=932) from a geographically defined district in southern Finland were recruited. The risk of developing asthma was significantly higher among current smokers with an adjusted odds ratio (OR) of 1.33 (95% confidence interval 1.00–1.77) and among ex-smokers with an adjusted OR 1.49 (1.12–1.97) compared with never-smokers. Among current smokers, the risk increased up to 14 cigarettes·day−1, and a similar trend was observed in relation to cumulative smoking. In conclusion, the current results support the hypothesis that smoking causes asthma in adulthood.

Environmental Tobacco Smoke and Adult-Onset Asthma: A Population-Based Incident Case–Control Study

OBJECTIVES The authors assessed the effects of environmental tobacco smoke (ETS) on the development of asthma in adults. METHODS In the Pirkanmaa district of South Finland, all 21- to 63-year-old adults with new cases of asthma diagnosed during a 2.5-year period (n = 521 case patients, out of 441 000 inhabitants) and a random sample of control subjects from the source population (932 control subjects) participated in a population-based incident case-control study. RESULTS Risk of asthma was related to workplace ETS exposure (adjusted odds ratio [OR] = 2.16; 95% confidence interval [CI] = 1.26, 3.72) and home exposure (OR = 4.77; 95% CI = 1.29, 17.7) in the past year. Cumulative ETS exposure over a lifetime at work and at home increased the risk. CONCLUSIONS This study indicates for the first time that both cumulative lifetime and recent ETS exposures increase the risk of adult-onset asthma.

Dampness and molds in day-care centers as an occupational health problem

To assess the occurrence of respiratory and other symptoms among workers in relation to dampness in day-care centers, a random sample of 30 day-care centers in the city of Espoo, Finland, was selected for the study. The study population consisted of 268 female day-care workers, who filled in a questionnaire. Dampness was found to be common: water damage had taken place in 70% of the centers, and workers perceived mold odor in 17% of them. Adjusted risk of work-related eye and respiratory symptoms was in general higher among the day-care workers exposed to both water damage and mold odor than among the unexposed. The prevalence of eye symptoms was statistically significantly higher. The results provide new evidence of the importance of dampness and mold problems in the work environment as determinants of respiratory and irritative symptoms.

Breastfeeding and childhood asthma: a six-year population-based cohort study

BackgroundThe question of the protective effect of breastfeeding on development of asthma has raised substantial interest, but the scientific evidence of the optimal duration of breastfeeding is controversial.MethodsThe authors elaborated the optimal duration of breastfeeding with respect to the risk of asthma primarily, and secondarily to the risk of persistent wheezing, cough and phlegm in school age in a population-based cohort study with the baseline in 1991 and follow-up in 1997. The study population comprised 1984 children aged 7 to 14 years at the end of the follow-up (follow-up rate 77). Information on breastfeeding was based on the baseline survey and information on the health outcomes at the follow-up.ResultsThere was a U-shaped relation between breastfeeding and the outcomes with the lowest risk with breastfeeding from four to nine months for asthma and seven to nine months for persistent wheezing, cough and phlegm.ConclusionOur results suggest a U shape relation between duration of breastfeeding and risk of asthma with an optimal duration of 4 to 6 months. A true concave relation would explain the inconsistent results from the previous studies.

Ventilation and indoor air quality in Finnish daycare centers

Abstract The purpose of this study was to assess the performance of ventilation and the indoor air quality in Finnish daycare centers and to evaluate the effect of ventilation and building design on indoor air quality. A random sample of 30 daycare centers in the city of Espoo (part of the Helsinki metropolitan area) was selected for the study. The measurements during October and November 1990 consisted of air flows, temperature, relative humidity, concentration of CO 2 , VOC and formaldehyde, and odor intensity. The measurement period was one day. The air flows in the childrens rooms varied remarkably, the range being 0–11 L/s per person (average 3.8 L/s per person). Only 30% of the rooms achieved the Finnish guide value of 5 L/s per person. The air temperature varied from 19°C to 26°C (average 22.2°C). The carbon dioxide concentration measured when the room was occupied varied from 400 to 2500 μL/L (average 810 μL/L). On average, the CO 2 concentration was statistically significantly higher in the older daycare centers (constructed before 1981) with mechanical exhaust than in the newer buildings (constructed from 1981 onward) with balanced mechanical ventilation. Correspondingly, the air flows and temperatures were significantly lower on average. The workers were asked to state their experience of poor indoor air quality during the past twelve months; the most common perception was unpleasant odors (60%). Water damage and moisture problems were also common in the daycare centers (70%). The results indicate that there is much room for improvement in the indoor air quality of daycare centers.

Ventilation rate as a determinant of symptoms and perceived odors among workers in daycare centers

Abstract The objective of this study was to assess symptoms related to the sick building syndrome (SBS) and perceived odors among daycare workers, relative to ventilation rates in Finnish daycare centers. A random sample of 30 daycare centers in the city of Espoo was selected for the study. The study population consisted of 268 female nursing workers, who filled in a questionnaire inquiring about symptoms, perceived air quality, and their possible personal and environmental determinants. The response rate was 96%. The ventilation system in most of the daycare centers (63%) was mechanical supply and exhaust; the rest of the centers (37%) had mechanical exhaust only. The exhaust airflows in the childrens rooms varied remakably, ranging from 0 to 11 L/s per person (average 4.0 L/s per person). The air change rate varied from 0 to 5 m 3 /hm 3 (average 1.61/h). Though potential personal and environmental confounders were controlled, no consistent associations were observed between the magnitude of airflows or air change rate and the occurence of symptoms or unpleasant odors experienced by the workers. The results indicate that relatively low mehanical ventilation rates are not associated with SBS symptoms and unpleasant odors in conditions where the potential sources of odor are strong and air change is not totally dependent on mechanical ventilation (windows are openable).