Self reported respiratory symptoms and diseases among hairdressers

Self-reported symptoms in Swedish hairdressers and association with exposure to volatile organic compounds (VOCs), including aldehydes

BACKGROUND

Working as a hairdresser involves combined exposure to multiple chemicals in hair treatment products that may induce symptoms in airways and skin.

METHODS

In this cross-sectional study, perceived symptoms among Swedish hairdressers at 10 hair salons were surveyed through a questionnaire. Associations with personal exposure to volatile organic compounds (VOCs), including aldehydes, and their corresponding hazard index (HI), based on the estimated risk for non-cancer health effects, were examined. The prevalence of four out of 11 symptoms was compared to available reference datasets from two other studies of office workers and school staff.

RESULTS

All 11 surveyed symptoms were reported among the hairdressers (n = 38). For the whole study group, the most prevalent symptoms were dripping nose (n = 7) and headache (n = 7), followed by eczema (n = 6), stuffed nose (n = 5), cough (n = 5) and discomfort with strong odors (n = 5). Significant relationships between exposure and symptoms were scarce. The exception was total VOC (TVOC) exposure adjusted to worked years in the profession; a difference was observed for any symptom between hairdressers in the group with 20 + years compared to 0-5 years in the profession (logistic regression, OR 0.03, 95% CI 0.001-0.70). Out of the four symptoms available for comparison, the prevalence of headache and cough was significantly higher in hairdressers than in controls (OR 5.18, 95% CI 1.86-13.43 and OR 4.68, 95% CI 1.17-16.07, respectively).

CONCLUSIONS

Adverse health effects related to occupation was common among the hairdressers, implying a need for exposure control measures in hair salons. Symptoms of headache and cough were more frequently reported by hairdressers than staff in offices and schools. A healthy worker effect among the hairdressers was indicated in the group with 20 + years compared to 0-5 years in the profession. Significant relationships between measured exposure and symptoms were scarce but gave information about advantages and disadvantages of the different exposure measures. The study design could be improved by increasing the size of the study population, using a better match of reference data and increasing the applicability and representability over time of the measured exposure.

Occupational respiratory morbidity and associated factors among hairdressers in Ethiopia: a cross-sectional study

OBJECTIVE

This study was designed to determine the prevalence and factors associated with occupational respiratory morbidity among hairdressers in Northwestern Ethiopia.

DESIGN

A cross-sectional study was conducted from 6 July 2022 to 17 August 2022. The data were collected using a standardised American Thoracic Society questionnaire. The collected data were entered into EpiData V.4.6 and analysed using Stata V.14. A multivariable logistic regression analysis was conducted to identify factors associated with occupational respiratory morbidity. The association was determined using an adjusted OR (AOR) with a 95% CI at a p value of <0.05.

SETTING

The study was conducted in Gondar city, Northwestern Ethiopia.

PARTICIPANTS

A total of 403 hairdressers participated in this study.

OUTCOME MEASURES

The primary outcome is the prevalence of occupational respiratory morbidity.

RESULTS

The total response rate was 95.5%. The majority, 250 (62%) of the respondents were women. The mean age (±SD) of the respondents was 27 (±6.0) years. The overall prevalence of occupational respiratory morbidity during the past 12 months was found to be 134 (33.3%) (95% CI (28.7% to 38.1%)). Female hairdressers (18.6%) showed greater respiratory morbidity than male hairdressers (14.7%). Working experience 3-5 years (AOR: 3.05; 95% CI (1.76 to 5.30)) and working experience >5 years (AOR: 6.22; 95% CI (2.73 to 14.16)), overweight (body mass index (BMI)) (AOR: 3.01; 95% CI (1.19 to 7.58)) and working near roadsides (AOR: 2.15; 95% CI (1.33 to 3.37)) were risk factors of occupational respiratory morbidity among hairdressers.

CONCLUSIONS

This study concluded that one-third of hairdressers experienced occupational respiratory morbidity. Longer work experience, higher BMI and working near roadsides were identified as significant risk factors for respiratory morbidity in hairdressers. Dietary calorie restrictions for overweight individuals and the development and implementation of air pollution mitigation measures targeted at roadside workers are advised to curb the problem.

Respiratory afflictions during hairdressing jobs: case history and clinical evaluation of a large symptomatic case series

OBJECTIVES

Respiratory symptoms at work are common among hairdressers. Various working materials, most notably bleaching ingredients such as ammonium persulfate, have been made responsible. The objective of this study is to achieve a better understanding of work-related respiratory symptoms of hairdressers by describing common features in a large affected collective.

METHODS

One hundred forty-eight hairdressers with respiratory symptoms at work presenting between 2012 and 2019 were consecutively included in a case series. Anamnestic and diagnostic data including pulmonary function and allergy testing were retrospectively compiled from records and analysed. Additionally, cases were categorised in five groups with respect to occupational causation certainty.

RESULTS

30% of the predominantly female collective had changed jobs or were on longer sick-leave. Besides respiratory symptoms, 10% also reported contact urticaria to blonde dyes. In 60% an obstructive airway disease was confirmed. A specific hypersensitivity reaction to ammonium persulfate was found in 15%. Group 1 with a proven immunological occupational causation showed significantly lower age (p < 0.001) and tenure time (p = 0.001), higher sensitization rates against environmental allergens as well as a higher total IgE (p = 0.015), compared to group 4 (obstructive airway disease, specific occupational causation unlikely).

CONCLUSIONS

This case series contributes to a better characterization of work-related respiratory symptoms in hairdressing as one of the largest examined collectives of symptomatic hairdressers. Ammonium persulfate as the most common specific cause showed signs of a type-I-like hypersensitivity reaction with typical risk factors for atopy. Prick testing is recommended in all symptomatic cases. However, a specific occupational causation often cannot be proved.

Long-Term Exposure to Essential Oils and Cardiopulmonary Health from a Population-Based Study

It is still unknown whether long-term inhalation of indoor air pollutants from ambient essential oil is associated with increased cardiopulmonary events. We recruited 200 healthy homemakers to conduct a prospective observation study in Northern Taiwan. We measured heart rate (HR), systolic blood pressure (SBP), diastolic BP (DBP), peak expiratory flow rate (PEFR), and indoor air pollutants four times per year for each participant between 2008 and 2018. Moreover, a questionnaire related to essential oil usage, home characteristics, and health status was filled out with each participant. The association between essential oil usage and cardiopulmonary health was determined using mixed-effects models. The mixed-effects models showed a significant association between essential oil usage and adverse cardiopulmonary effects including increased HR and BP and decreased % predicted PEFR among participants with heavy use of essential oils. No significant association between essential oils usage and adverse cardiopulmonary effects was observed among participants without essential oils usage or participants with mild use of essential oils (less than one hour per day). We concluded that exposure to indoor air pollution related to essential oils was associated with adverse cardiopulmonary effects among participants with essential oil usage more than one hour per day.

Working Conditions and Health Risk Assessment in Hair Salons

Objective:The aim of this study was to assess the chemical and physical work conditions in hair salons and to analyze health risk of exposure to VOCs for the hairdressers of hair salons. Methods: This study was carried out at 4 selected hair salons close to universities in Surat Thani province, Thailand. VOCs were collected by area sampling using charcoal tubes (9 samples per salon). The air samples were analyzed using GC/FID. The noise levels, illumination, and temperature were measured by using sound level meter, lux meter, and WBGT, respectively. Results: Toluene, cyclohexanone, xylene, and hexane were the most frequently found across the hair salons. All of the VOCs concentration was highest in the mixing area. All of hair salons had cancer risk exceeding 1 × 10-6 and HI > 1.0, indicating that indoor air pollution may affect hairdresser's health. The average VOCs concentrations after installation of local exhaust ventilation and open the door for 30 minutes before closing the hair salon, was significantly lower than before and after installation of the local exhaust ventilation. The WBGT indoors varied within 22 to 28°C, sound pressure levels within 71 to 76 dBA, and illumination within 70 to 400 lux. The noise levels and temperature in the hair salons were satisfactory on the scale of the Ministry of Labor (Thailand). Conclusions:Installing and using proper ventilation in hair salon are recommended to eliminate health effects. Hairdresser worked in poor lighting that should be improved to appropriate levels (>1000 lux).

Non-Combustible Source Indoor Air Pollutants Concentration in Beauty Salons and Associated Self-Reported Health Problems Among the Beauty Salon Workers

Background

Cosmetic products emits Total Volatile Organic Compound (TVOC) and Particulate Matter with an aerodynamic diameter of 10 micrometers (PM₁₀) of different sizes and characteristics with adverse health effects. Despite the increasing need for cosmetic products, related pollutants level of concentration from beauty salon is not well understood in developing countries.

Objective

This study aims to assess indoor air pollutant concentrations in the beauty salon and self-reported health problems among the salon workers in Jimma town.

Methods

A cross-sectional study design was used on 87 beauty salons from May 13-24, 2019. The concentrations of PM_10, TVOCs, CO₂, room temperature, and relative humidity were measured and triangulated with the survey data collected through measurements and questionnaires. A statistical software package, SPSS v.21, was used to analyze the data. A binary logistic regression was used to analyze categorical data and linear regressions to predict pollutants level and associated health outcomes.

Results

The results show that 93.1% of the respondents are females, and 85% were below 30 years old. More than 60% of the respondents were married individuals. 56.3% and 44.8% of the workers work over 10 hours per day and work the whole week. 34.6% of the workers reported as worked during pregnancy. About 70% of the workers know the harmful effects of cosmetics, benefits of ventilation, and Personal Protective Equipment (PPE) use, but only 19.4% use face masks. The majority (88.5%) reported health problems after starting work in the beauty salon. The mean volume of the beauty salon was 36.3 m^3, with a mean PM₁₀ concentration of 0.465 mg/m³ and a mean TVOC concentration of 1034.2 µg/m³. These air pollutants have shown a statistically significant association with self-reported health problems. Hence, urgent intervention with subsequent continuous awareness creation is needed to reduce the health consequences of a beauty salon's indoor air pollutants.

Occupational exposures and respiratory symptoms and lung function among hairdressers in Iran: a cross-sectional study

Objective

Exposures at hairdressers’ work have been reported to lead to an increased risk of several health outcomes. The present study aimed to investigate the relations between occupational exposures and respiratory symptoms and lung function among hairdressers in Iran.

Methods

We conducted a cross-sectional study to compare potential respiratory effects among 140 women working as hairdressers to such effects among 140 women working as office workers (administrative personnel). Both groups worked in Shiraz, Iran. Respiratory symptoms were assessed by a standard respiratory questionnaire. The questionnaire also inquired about substances used and workspace conditions, including ventilation type. Lung function levels were measured by spirometry.

Results

Respiratory symptoms, including cough, wheezing, shortness of breath, and chest tightness were significantly more frequent in hairdressers compared to the reference group (p < 0.05). After controlling for potential confounders, hairdressers had a prevalence ratio (PR) of 2.18 (95% CI 1.26–3.77) for cough, 9.59 (95% CI 1.004–91.73) for wheezing, 2.06 (95% CI 1.25–3.39) for shortness of breath, and 3.31 (95% CI 1.84–5.97) for chest tightness compared to the reference group. Lung function parameters (including VC, FVC, and FEV1) were significantly reduced in hairdressers (p < 0.001). Absence of air conditioning predicted greater reduction in lung function (p < 0.05) in the exposed. Decrease in FVC with normal FEV1/FVC in the exposed group suggested existence of restrictive lung function.

Conclusions

This study provides evidence of increased prevalence of respiratory symptoms and restrictive lung function impairment among hairdressers in Iran.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00420-020-01645-z.

Phthalates Exposure and Occupational Symptoms among Slovakian Hairdressing Apprentices

The objectives of the study were to examine occupational exposure to phthalates of hairdressing apprentices from Slovakia (n = 74, 89.2% females; 10.8% males), outcomes related to body composition and pulmonary functions. We used high-performance liquid chromatography and tandem mass spectrometry to the quantified urinary concentration of phthalates. Pulmonary function test (PFT), anthropometric measurements, and questionnaire were also conducted. We observed a decrease of % of predicted values of forced vital capacity (FVC% of PV) related exposure to mono(2-ethyl-5-oxohexyl) phthalate (MEOHP; p = 0.054) and sum of bis(2-ethylhexyl) phthalate metabolites (∑DEHP; p = 0.037), and a decrease of % of predicted values of vital capacity (VC% of PV) related to exposure to MEOHP, ∑DEHP (p = 0.008), and mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP; p = 0.014) in females. We detected associations between forced vital capacity (FVC) with weight (p = 0.002) and fat-free mass index (FFMI, p = 0.010). Vital capacity (VC) and VC% of PV increased with weight, body mass index (BMI), waist circumference (WC), hip circumference (HC), waist-hip ratio (WHR), the waist-height ratio (WHtR), fat mass index (FMI) and FFMI in females (p ≤ 0.014). Results of multivariate regression between PFT and anthropometric parameters adjusted to phthalates indicated exposure to MnBP and MEHP, changing body structure (BMI and FMI), subsequently affecting values of FEV1/FVC.

Occupational phthalate exposure and health outcomes among hairdressing apprentices

We studied occupational exposure to phthalates from first-morning-void urine sample of hairdressing apprentices by HPLC-MS/MS analyses and association with health status. Metabolites of mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono ethyl phthalate (MEP), mono- n-butyl phthalate (MnBP) and mono-iso-butyl phthalate (MiBP) were detected in all urine samples, followed by metabolites mono(2-ethyl-5-oxohexyl) phthalate (MEOHP) and mono(2-etylhexyl) phthalate (MEHP) occurring in 97.06% and 86.76% of samples, respectively. Positive associations for females were observed between MnBP and fat-free mass index (FFMI) and age; negative associations were found between MEHP, MEOHP, MEHHP, sum of MEHP, MEHHP, MEOHP and vital capacity and also between MEHP and forced vital capacity (FVC of predicted value (PV)). Lengths of exposure were associated to MnBP, MEHHP, and MEP. We also documented positive associations between anthropometry (body mass index, waist-to-height ratio (WHtR), FFMI, fat mass index) and pulmonary function FVC% of PV for females and negative associations between WHtR, waist-to-hip ratio, FFMI and ratio of forced expiratory volume in 1 s (FEV₁) to FVC (FEV₁/FVC). We assume that factors of occupational environment of hairdressing apprentices are affected by phthalates and resulted in negative outcomes in breathing mechanism and influence of body composition. Adipose tissue could play role as confounding factor in urine excretion of phthalates because of their lipid solubility and accumulation.

Exposure of hairdressers to the main cosmetics used in hairdressing salons in France: A preliminary study

In recent years, more attention has been given to chemical exposure in hairdressers. This increasing interest is largely due to the various respiratory and skin symptoms observed in hairdressers. According to these symptoms, hairdressers are in contact with various sources of exposure. Particularly in France, little information is available to assess professional exposure of hairdressers. In order to gather information to assess exposure in hairdressers, 11 hairdressing salons were visited. All the salons were located in Brest City (France). Preferentially, small hairdressing salons were visited. Observations were performed to obtain salon characteristics and to record workers' practices. Calculations revealed that in the worst-case scenario, dermal professional exposure reaches 14.68 and 13.67 mg/kg/day for hair coloring and highlighting mixtures, respectively. Inhalation exposure represents 14.2 and 18.1 mg/kg/day for hair coloring and highlighting mixtures, respectively. These exposure values represent baseline values for exposure of French hairdressers working in small hairdressing salons.

High occurrence of rhinitis symptoms in hairdressing apprentices

BACKGROUND

Little is known about the occurrence of respiratory symptoms among hairdressing apprentices during their training. Therefore, in this study, we examined whether hairdressing apprentices are at increased risk of rhinitis and asthma symptoms when compared with other young adults from the general population.

METHODS

A questionnaire was completed by 504 hairdressing apprentices and 1400 control participants from the general population with a similar age, gender, and geographic distribution.

RESULTS

The 1-year prevalence of rhinitis symptoms was higher in hairdressing apprentices than in controls (58.1% vs 46.6%; odds ratio, 1.59; 95% confidence interval, 1.30-1.98), and the prevalence was higher among hairdressing apprentices in the last years of training compared with apprentices in the first year of training (62.4% vs 41.8%, p = 0.003). Current smoking was more common in hairdressing apprentices (28.4% vs 17.2%, p < 0.001). Asthma symptoms were equally common in the 2 groups; however, hairdressing apprentices had a later age of onset of wheezing than did the controls (18 years vs 14 years, p < 0.00001) and a decreased risk of wheezing (odds ratio, 0.72; 95% confidence interval, 0.54 to 0.95) after adjusting for smoking, education level, and degree of rurality. Bleaching products were the most frequently reported cause of rhinitis and asthma symptoms in hairdressing apprentices.

CONCLUSIONS

Hairdressing apprentices seem to have an increased risk of occupational rhinitis, and bleaching products are the main cause of respiratory symptoms. In addition, our findings suggest that a healthy worker effect exists in relation to asthma among hairdressing apprentices.

Dust-free bleaching powder may not prevent symptoms in hairdressers with bleaching-associated rhinitis

Objective:

Hairdressers have an increased risk for airway symptoms especially when using hair-bleaching powder containing persulfate. To minimize exposure, dust-free bleaching powder (DFP) has been made available. We studied the effects of regular powder (RP) or DFP on the airway symptoms of hairdressers with hair-bleaching associated rhinitis.

Methods:

Twelve hairdressers each performed three hair-bleachings on a wig in an exposure chamber. Half of the subjects used RP and half used DFP. Exposure to persulfate and ammonia was measured. Before and after each bleaching, the participants stated their degree of airway symptoms on a visual analogue scale. Nasal lavage and blood were sampled before exposure, after the last bleaching, and in the morning after exposure to measure inflammatory markers.

Results:

Exposure to persulfate was higher when using RP compared to DFP, 22 (11-55) vs. 12 (8-13) μg/m³; median (min-max). Exposure to ammonia did not differ between the groups. Both groups reported an increase in asthma-like symptoms and this increase was significant. Neutrophils, lymphocytes, and monocytes increased after exposure in both groups; monocytes decreased the day after. In nasal lavage, IL-8 was increased the morning after for both types of powder, and the increase was significant in the total group. IL-6 increased immediately after exposure and the day after only in the group using RP.

Conclusions:

Although DFP powder emits lower levels of persulfate, effects are still elicited in symptomatic hairdressers.

Occupational Respiratory and Musculoskeletal Symptoms among Egyptian Female Hairdressers

Hairdressing is associated with exposure to a variety of harmful agents which have been linked to respiratory and musculoskeletal disorders in hairdressers. This study aimed to identify respiratory and musculoskeletal disorders in hairdressers compared to office workers. A cross-sectional study was conducted on 80 female hairdressers and 50 matched controls. A structured questionnaire was used to collect information on personal and occupational data, hairdressing activities, the presence of respiratory symptoms and the prevalence of musculoskeletal pain in the past 12 months. Reported symptoms were compared between hairdressers and controls. The associations between self-reported symptoms and hairdressing activities were investigated. Hairdressers were more likely to report symptoms than controls particularly for those who were older, with higher body mass index and longer duration of work as hairdresser. There were significant associations between frequent hair treatments (bleaching, dye and wave) and hand dermatitis (P < 0.001), running nose (P < 0.05), eye irritation (P < 0.01) and phlegm (P < 0.05). Elbow pain and shoulder and back pain were the most prevalent musculoskeletal pains in the past 12 months (13.8 and 12.5% respectively), back and knee pains were the most frequent chronic pain (7.5%), hand and wrist pain led 12.5% of hairdressers to visit a doctor and shoulder pain and back pain indicated a period of sickness absence in 13.8% of hairdressers. Musculoskeletal disorders were associated with manual handling, prolonged standing, strenuous shoulder movements and awkward body posture. Hairdressing is associated with increased risk to respiratory and musculoskeletal disorders due to adverse work conditions.

Targeted proteomic analyses of nasal lavage fluid in persulfate-challenged hairdressers with bleaching powder-associated rhinitis

Hairdressers have an increased risk for developing airway symptoms, for example, asthma and rhinitis. Persulfates, which are oxidizing agents in bleaching powder, are considered important causal agents for these symptoms. However, the underlying mechanisms are unclear. The aim was therefore to measure proteomic changes in nasal lavage fluid from persulfate-challenged subjects to identify proteins potentially involved in the pathogenesis of bleaching powder-associated rhinitis or candidate effect biomarkers for persulfate. Also, oxidized peptides were measured to evaluate their usefulness as biomarkers for persulfate exposure or effect, for example, oxidative stress. Samples from hairdressers with and without bleaching powder-associated rhinitis were analyzed with liquid chromatography tandem mass spectrometry using selected reaction monitoring to target 246 proteins and five oxidized peptides. Pathway analysis was applied to obtain a functional overview of the proteins. Several proteins involved in biologically meaningful pathways, functions, or disorders, for example, inflammatory responses, oxidative stress, epithelium integrity, and dermatological disorders, changed after the persulfate challenge. A list with nine proteins that appeared to be affected by the persulfate challenge and should be followed up was defined. An albumin peptide containing oxidized tryptophan increased 2 h and 5 h after the challenge but not after 20 min, which indicates that such peptides may be useful as oxidative stress biomarkers.

Asthma and respiratory symptoms among hairdressers in Denmark: results from a register based questionnaire study

BACKGROUND

Hairdressers are at risk of developing occupational respiratory disorders due to persulfates and other hairdressing chemicals.

METHODS

A register based questionnaire study comprising 7,840 graduates from hairdressing vocational schools was conducted. The postal questionnaire concerned self-reported asthma, airway symptoms, occupation, smoking, and atopic dermatitis.

RESULTS

A response rate of 67.9% was obtained. The hairdressers reported asthma (11.2%), cough (25.3%), nasal congestion (24.0%), and rhinitis (18.2%). Less than 1/3 of all hairdressers with suspected occupational asthma reported their asthma as an occupational disease to the authorities. In total, 27.3% were daily smokers; the smoking pattern was similar between hairdressers with and without asthma. Local exhaust ventilation was only used consistently by 63.8% for permanent waving and hair coloring procedures.

CONCLUSIONS

Asthma and especially respiratory symptoms were commonly reported by hairdressers, but rarely reported as an occupational disease. Local exhaust ventilation was inconsistently used. Our results underline the need for improved measures to ascertain and prevent occupational asthma in hairdressers.

Respiratory function and chemical exposures among female hairdressers in Palestine

BACKGROUND

Hairdressers are exposed to chemicals and work tasks that may cause respiratory symptoms. There is little awareness of occupational health among hairdressing salons in Palestine.

AIMS

To characterize respiratory symptoms, lung function, and knowledge of exposure to hazards among female Palestinian hairdressers.

METHODS

Cross-sectional study of female hairdressers and controls of female university students and staff. Working history and respiratory symptoms were collected using questionnaire. Lung function was measured. Working conditions were characterized in salons.

RESULTS

A total of 170 hairdressers from 56 salons and 170 controls participated. Nineteen per cent of the hairdressers reported wheezing versus 11% in the control group. The mean forced vital capacity was 3.31 l compared with 3.42 l for controls. Adjusting for age and height, there was a forced expiratory volume in 1 s reduction of 0.093 l (95% confidence interval (CI) = 0.06-0.15) comparing hairdressers with controls. A small number of hairdressers used respiratory protective equipment, and satisfactory ventilation in salons were lacking.

CONCLUSIONS

Female hairdressers had higher prevalence of reported asthma and respiratory symptoms than the controls, but these differences reduced markedly when adjusted for age, height, weight and years of education. They had lower lung function measurements than the control group. Increasing the awareness of occupational health hazards and improving the work conditions for the hairdressers in Palestine is needed. Possible bias could be present as hairdressers might have over reported symptoms or lung function measurements might be affected by differences in socioeconomic status between the two groups.

Self-reported work-related symptoms in hairdressers

BACKGROUND

Detailed studies of current symptoms reported by hairdressers and of the training received to reduce the health risks associated with this work are uncommon.

AIMS

To document current levels of self-reported health problems in hairdressers, compared to non-hairdressing controls.

METHODS

An interviewer-led questionnaire recording demographic information, work history, health training levels and the presence of self-reported respiratory, skin, musculoskeletal and non-specific symptoms was administered.

RESULTS

In total, 147 hairdressers, 86% of whom were female (median age 27 years) and 67 non-hairdressing controls, all female (median age 38 years) were recruited. Following adjustment for age, smoking and years worked, hairdressers reported significantly higher levels of musculoskeletal problems, including work-related shoulder pain (OR 11.6, 95% CI 2.4-55.4), work-related wrist and hand pain (2.8, 1.1-7.6), work-related upper back pain (3.8, 1.0-14.9), work-related lower back pain (4.9, 1.5-15.9) and work-related leg/foot pain (31.0, 3.8-267.4). The frequency of self-reported asthma was similar in both groups (hairdressers 16%, controls 17%) as was chest tightness and wheeze. Work-related cough was significantly more frequently reported in hairdressers than in controls (13.2, 1.3-131.5). While hairdresser training was commonplace, such training did not always appear to have resulted in awareness of potential workplace health risks.

CONCLUSIONS

This study identified frequently reported musculoskeletal, skin and respiratory symptoms in hairdressers. This points to a need to develop training that not only deals with risk assessment but also informs hairdressers about the health risks of their work.

Occupational health risks of barbers and coiffeurs in Izmir

The objective of this study was to examine self-reported occupational health risks and health complaints of barbers and hairdressers. A total of 1284 individuals from 300 workplaces in Izmir participated in this study. The workers completed the questionnaires during their training in occupational health. Self-reported symptoms were allergy: 35% and musculoskeletal symptoms: 32%. The frequency of allergy complaints was found to be significantly higher in older individuals and in women. Allergic complaints were more frequent in i) those having history of allergy, ii) in the group where the use of protective clothing and gloves was lower, iii) in smokers and in those who found ventilation in the workplace to be inadequate. Only 41.2% reported that they used gloves and 15.2% reported the use of protective clothing within the last month. It appears that poor occupational factors in barbers' salons and exposure to hairdressing chemicals bring about health problems of the hairdressers.

Trends in occupational airway diseases in German hairdressers: frequency and causes

BACKGROUND

Hairdressers are exposed to several allergens and irritants known to cause obstructive airway diseases (OAD). In the early 1990s, high incidence rates of OAD were observed in German hairdressers. It was expected that modification of formulations would resolve the problem of high OAD rates in hairdressers.

METHODS

The numbers of confirmed cases are reported of allergen-, latex- and irritant-induced OAD in German hairdressers, as registered by the responsible compensation board during 1998 and 2007. Hairdressing components reported as causative for OAD in hairdressers were analyzed. The incidence rates of OAD in hairdressers were compared with rates in healthcare professionals, as both occupations had high rates of OAD in the 1990s.

RESULTS

From 1998 until 2003, the total number of confirmed cases of allergen-, latex- and irritant-induced OAD stayed at a plateau of 60 cases annually in hairdressers, after which a downward trend was apparent. The number of irritant-induced OAD cases did not fall during this overall downward trend. Hair dyes and acid perms were most often identified as the substances causing OAD in hairdressers. In healthcare professionals, the downward trend in OAD is more pronounced than in hairdressers, mainly due to a decrease in latex-induced cases.

CONCLUSIONS

The number of allergen- and irritant-induced cases of OAD in German hairdressers is still high. Exposure to known airway irritants is still occurring in spite of modification of the formulations. Continuous medical surveillance of hairdressers is recommended, in order to detect individual susceptibility, especially in apprentices.

Adverse health outcomes among cosmetologists and noncosmetologists in the Reproductive Outcomes of Salon Employees (ROSE) study

The purpose of this study was to examine adverse health outcomes, including those related to cardiovascular and skin health as well as respiratory functions, among cosmetologists aged 21 to 55 yr and to compare data to women of the same age working in other occupations. Self-reported data were analyzed from 450 cosmetologists and 511 women in other occupations who participated in the Reproductive Outcomes of Salon Employees (ROSE) study in Maryland. Odds ratios (OR) and 95% confidence intervals (95% CI) were computed using logistic regression to examine the associations between cosmetologist occupation and each adverse health outcome adjusted for age, education, and smoking status. Cosmetologists were at significantly increased risk of depression compared to noncosmetologists after adjustment for age, education, and smoking status (OR 1.49; 95% CI 1.10, 2.00). There were no statistically significant associations between cosmetology occupation and the other adverse health outcomes, including those related to allergies and skin disorders, in both the unadjusted and adjusted analyses. Cosmetologists may be exposed to chemicals in the salon that lead to depression. Future study needs to be conducted to examine specific chemical exposures in the salon. This will help to provide information required for the development of best occupational safety practices among salon workers.

Chemical exposure and occupational symptoms among Portuguese hairdressers

Hairdressing is predominantly a female activity, in which several chemicals are handled, some of which are known to be allergenic and potentially carcinogenic. Several epidemiological studies showed an association between occupational exposure to chemicals in hairdressing salons and skin and respiratory-tract conditions. The aim of this study were to characterize the occupational exposure to total volatile organic compounds (VOC) and ammonia (NH₃) in 50 Portuguese hairdressers' salons and to analyze the prevalence of respiratory and skin symptoms in 134 hairdressing professionals. Data indicated that internal sources of total VOC are mainly due to indoor sources, with average concentrations (1.4 mg/m³) above the Portuguese reference levels (0.6 mg/m³). Of the hairdressers' salons studied, 4% had a mean NH₃ concentration higher than Portuguese (20 ppm) and American Conference of Industrial Hygienists (ACGIH) (25 ppm) reference levels. Hand dermatitis was the occupational symptom most reported by hairdressers (50%), followed by eye irritation (43%). The results of this study suggest that hairdressers' occupational activities are linked with higher risk of developing hand and wrist/arm dermatitis and symptoms in the upper respiratory tract. The proper use of disposable gloves, hands, wrists, and arms skin monitoring, and the frequent use of moisturizers in the workplace are effective measures to prevent the occurrence of dermatitis in these professionals. Displacement ventilation and/or local exhaust with adequate air exchange rate are recommended particularly in technical areas where hairdressing chemicals are mixed.

Time-dependent proteomic iTRAQ analysis of nasal lavage of hairdressers challenged by persulfate

Hairdressers are frequently exposed to bleaching powder containing persulfates, a group of compounds that may induce hypersensitivity in the airways. The mechanism causing this reaction is not clear. The aim of this study was to identify changes in the nasal lavage fluid proteome after challenge with potassium persulfate in hairdressers with bleaching powder-associated rhinitis. Furthermore, we aimed to compare their response to that of hairdressers without nasal symptoms, and atopic subjects with pollen-associated nasal symptoms. To study the pathogenesis of persulfate-associated rhinitis, the response in protein expression from the upper airway was assessed by time-dependent proteomic expression analysis of nasal lavage fluids. Samples were prepared by pooling nasal lavage fluids from the groups at different time points after challenge. Samples were depleted of high-abundant proteins, labeled with iTRAQ and analyzed by online 2D-nanoLC-MS/MS. Differences in the protein pattern between the three groups were observed. Most proteins with differentially expressed levels were involved in pathways of lipid transportation and antimicrobial activities. The major finding was increased abundance of apolipoprotein A-1, 20 min postchallenge, detected solely in the group of symptomatic hairdressers. Our results suggest there may be differences between the mechanisms responsible for the rhinitis in the symptomatic and atopic group.

Musculoskeletal disorders among cosmetologists

A cross-sectional study was performed to investigate the relationships between physical, psychosocial, and individual characteristics and different endpoints of low back, neck, shoulder, hand/wrist and knee musculoskeletal complaints among cosmetologists in Athens, Greece. The study population consisted of 95 female and seven male beauty therapists (response rate 90%) with a mean age and duration of employment of 38 and 16 years, respectively. Neck pain was the most prevalent musculoskeletal complaint, reported by 58% of the subjects, while hand/wrist and low back complaints resulted more frequently in self-reported consequences (chronicity, care seeking and absenteeism). Significant relationships were found between self-reported physical risk factors like prolonged sitting, use of vibrating tools, reaching far and awkward body postures and the occurrence of musculoskeletal disorders at various body sites. Among psychosocial variables co-worker support and skill discretion seem to be the most important reflecting organizational problems and cognitive-behavioral aspects. The study results also suggest that effective intervention strategies most likely have to take into account both ergonomic improvements and organizational aspects.

Trichoptysis: a hairy presentation of a rare tumour

We describe the case of a 17-year-old hairdresser who presented with haemoptysis and trichoptysis due to benign intrapulmonary teratoma and her surgical management. The clinical and radiological features of this rare tumour are reviewed and the symptom of trichoptysis discussed.

Effect of occupation and smoking on respiratory symptoms in working children

OBJECTIVES

To compare the respiratory symptoms and the lung function of children who work in different occupational groups.

METHODS

The study was performed among children attending vocational training centers. The participants were evaluated in six different occupation groups. Chronic cough, wheezing and shortness of breath were evaluated by questionnaire. The association of independent variables with the respiratory symptoms was investigated through both univariate and multivariate methods.

RESULTS

Among 642 children, 534 were males; the mean age was 17.7 +/- 1.0 years. Using an internal reference group, the odds ratios of chronic cough were significantly higher in the lathe (OR: 2.0, 95%CI: 1.07-3.74), coiffure (OR: 1.94. 95%CI: 1.01-3.70), and electricity-construction (OR: 2.63, 95%CI: 1.06-6.54) groups after adjustment for smoking, age, gender, and work characteristics. There were no significant differences in spirometric values between occupational groups in either smoking or non-smoking males. In non-smoking females, median values of FEV(1) (P: 0.046), PEF (P: 0.005) and FEF(25-75%) (P: 0.019) were lower in the textile compared to the coiffure group. There was no significant association between the total working time and spirometric values. There was no statistically significant relationship between the work-related factors and the smoking status.

CONCLUSIONS

The prevalence of chronic cough was higher in the lathe, coiffure, and electricity-construction groups and pulmonary function tests were lower in the non-smoking textile female group. Working children should be screened for respiratory symptoms and disease.

Gene expression in nasal lavage from hairdressers exposed to persulphate

OBJECTIVES

Many hairdressers experience work-related symptoms from the airways caused by bleaching powder. This contains persulphates, which could be irritating to the mucous membrane and also may evoke an allergic reaction. However, specific IgE antibodies are difficult to detect. We found earlier that hairdressers with work-related bleaching powder-associated nasal symptoms reacted to persulphate, but that atopics also did and that the mechanism appeared to be similar in the two groups. In this study, we analysed gene expression of cytokines in the nose in order to further investigate the mechanism for work-related bleaching powder-associated nasal symptoms.

METHODS

The study subjects belonged to either hairdressers with work-related bleaching powder-associated nasal symptoms (S; n = 6), hairdressers without work-related bleaching powder-associated symptoms (WS; n = 7) or atopics (A; n = 6). Nasal lavage was performed before and during (up to 4 h after the last challenge) provocation with potassium persulphate. Expression of two genes involved in allergic inflammation [interleukin 5 (IL5) and IL13] and one involved in cell-mediated immunity (interferon-gamma; IFNG) were analysed in nasal lavage with quantitative PCR.

RESULTS

The change of IL5 in the S group differed when compared to the WS group (P = 0.0051), in the A group when compared to the WS group (P = 0.014), but not in the S group when compared to the A group (P = 0.82). The change of IL13 in the A group differed when compared to the S (P = 0.041) and WS (P = 0.014) groups, but no difference was noticed between the S and WS groups (P = 0.30). The relative level of IFNG increased from before challenge to during challenge in the S group (P = 0.031).

CONCLUSIONS

Symptomatic hairdressers showed increased expression of IL5 and IFNG, but not IL13, during challenge. Hairdressers without work-related bleaching powder-associated nasal symptoms showed no markedly changed reaction. Atopics showed increased expression of IL5 and IL13. Thus, this may indicate a difference in the mechanism of symptoms between symptomatic hairdressers and atopics. However, due to the low number of participants, further studies are needed to elucidate the mechanism for persulphate-associated nasal symptoms.

Persulphate challenge in female hairdressers with nasal hyperreactivity suggests immune cell, but no IgE reaction

PURPOSE

The aim of this study was to examine the effects of persulphate on the nasal mucosa and on the immune cells in hairdressers suffering from bleaching powder associated rhinitis (BAR) versus subjects with rhinitis not previously exposed to bleaching powder.

METHODS

Fifteen hairdressers (S) with BAR, 14 without symptoms (WS) and 12 atopics (A) with rhinitis but without exposure to bleaching powder were studied. Each performed a nasal challenge with persulphates. Effect parameters were symptom score, acoustic rhinometry, albumin in nasal lavage, subpopulations of lymphocytes in blood and specific serum antibodies.

RESULTS

The S group had a post-challenge increase in nasal symptoms and nasal lavage albumin. The A group reacted to a lesser intent. The S and A groups showed an increase in Th1 cells. An HLA class II cell expression was noticed in both groups of hairdressers. No evidence of a type 1 reaction (immediate type) to persulphate was noticed.

CONCLUSIONS

Persulphate challenge affects hairdressers with BAR, but also atopics. The reaction may be driven by a Th1 cell activation.

Inhalation challenge test in the diagnosis of occupational rhinitis

BACKGROUND

Evaluations of rhinitis reactions in inhalation challenges (ICs) are sparse compared with research on nasal challenges. This study evaluates the outcome of IC tests in assessing occupational rhinitis (OR). It presents the largest rhinologic IC data in the literature, analyzing the exposure method of various agents causing OR and their relation to asthma.

METHODS

Challenge tests performed on 829 individuals with suspected cases of OR were reviewed. Results from both exposures with occupational agents (n = 1229) and placebo (n = 838) were evaluated.

RESULTS

A total of 10% of the occupational ICs (n = 123) were positive, suggesting OR, and 13% (n = 161) showed asthmatic reaction in the same challenge. In control challenges 2% showed rhinitis and 6% showed asthma symptoms. The most common agents tested were molds (160 tests), flours, and animal fodders (115 tests) and formaldehyde (122 tests). Obeche wood dust and latex produced positive nasal reactions the most frequently, followed by acid anhydrides.

CONCLUSION

Although IC is a resource-intensive methodology, the evaluation of nasal symptoms and signs together with bronchial reactions saves time and expense compared with the organization of multiple individual challenges. We encourage the simultaneous evaluation of both nasal and bronchial reactions in IC tests.

Respiratory effects of exposure to methacrylates among dental assistants

BACKGROUND

Case reports of occupational asthma in dental personnel have been published, but there is little data on the risk of respiratory disorders related to occupational exposure to methacrylates in dental assistants. The objective of this study was to investigate the relation of exposure to methacrylates to occurrence of respiratory symptoms and diseases among dental assistants.

METHODS

A cross-sectional study of female dental assistants from the membership register of the Finnish Association of Dental Hygienists and Assistants was conducted in the Helsinki metropolitan area. A CATI was carried out to collect information on health and exposures. A total of 799 dental assistants participated (response rate 87%).

RESULTS

Daily use of methacrylates was related to a significantly increased risk of adult-onset asthma (adjusted OR 2.65, 95% CI 1.14-7.24), nasal symptoms (1.37, 1.02-1.84), and work-related cough or phlegm (1.69, 1.08-2.71). Nasal symptoms showed a dose-response relation with increasing years of exposure to methacrylates, and those with >10 years of exposure had also increased risk of hoarseness, dyspnoea, and wheezing with dyspnoea. Dental assistants with a history of atopic diseases were particularly susceptible to exposure to methacrylates, the adjusted OR for adult asthma being in this group 4.18 (95% CI 1.02-28.55) and for nasal symptoms 2.11 (1.08-4.19).

CONCLUSIONS

This study provides new evidence that the risk of adult-onset asthma, nasal symptoms and other respiratory symptoms increase significantly with daily use of methacrylates in dental assistants' work. The results suggest that exposure to methacrylates poses an important occupational hazard for dental assistants.

Risk factors for asthma among cosmetology professionals in Colorado

PROBLEM

After receiving several reports of occupational asthma among cosmetology professionals, we studied the prevalence, work-attributable risk, and tasks associated with asthma in this industry.

METHODS

We selected a stratified random sample of cosmeticians, manicurists, barbers, and cosmetologists holding licenses in Colorado for a mail survey instrument.

RESULTS

The prevalence of physician-diagnosed asthma among the 1883 respondents (68% response rate) was 9.3%; of these, 67 (38%) developed asthma after entering the cosmetology profession. Multivariate analyses showed that hairstyling, application of artificial nails, and shaving and honing were significantly associated with asthma arising in the course of employment (P < 0.005) with relative risks of 2.6-2.9.

CONCLUSIONS

The increased risk of asthma with onset during employment among cosmetologists is probably attributable to their exposure to sensitizers and irritants in tasks demonstrated to be associated with asthma.

Exposure of hairdressing apprentices to airborne hazardous substances

BACKGROUND

Few studies have investigated exposure of hairdressing apprentices to airborne irritants. This study describes exposure levels of apprentices to chemical products used in hairdressing salons in relation with their activity.

METHODS

Following a two stages study design, a group of 300 students completed a questionnaire on their work activities and environment. Among these, a group of 28 subjects volunteered to undergo personal exposure and workplace concentrations measurements over a work shift, during a cold and a hot season, with the agreement of the salon owners. Three chemical substances were studied (ammonia, hydrogen peroxide and persulfates) because they are respiratory tract irritants and because their concentrations could be quantified within a 5 to 8 hour shift period.

RESULTS

Personal exposure values for H2O2 and NH3 (averages [standard deviations] are 0.05 [0.04] and 0.90 [0.76] mg.m(-3), respectively) were greater than workplace ambient air concentrations (corresponding values of 0.04 [0.03] and 0.68 [0.42] mg.m(-3)) for H2O2 and NH3, with no significant seasonal variation. By contrast, workplace concentrations of persulfates (0.019 [0.018] mg.m(-3)) were greater than personal exposure (0.016 [0.021] mg.m(-3), a finding that is consistent with the fact that bleaching is more often undertaken by senior hairdressers. However, all exposure values were lower than the current TLV TWA values. This study also shows that over half of technical spaces where chemical substances used for dying, permanenting or bleaching are manipulated, have no ventilation system, and not even a door or a window opening outside.

CONCLUSION

The study hairdressing salons, on average, were small, the most probable reason why occupational hygiene measures such as appropriate ventilation were too seldom implemented. As a consequence, young apprentices and senior hairdressers experience substantial exposure to known airways irritants.

Correlation between chemical-safety knowledge and personal attitudes among Taiwanese hairdressing students

BACKGROUND

Hairdressers are exposed daily to a variety of chemicals; insufficient protection and non-compliance are issues of concern in this trade. We examined the relationship between the knowledge hairdressing-students have concerning chemical safety and precautionary handling practices with their intentions and beliefs as regards chemical use, handling precautions, perceptions of associated risk, peer norms, and perceived self-efficacy toward preventing personal exposure.

METHODS

A total of 163 full-time students from two vocational schools were recruited to complete a questionnaire and a 60-min structured interview.

RESULTS

Students scoring lower in knowledge regarding chemicals were less likely to report the intention to wait for favorable air conditions prior to their using chemicals in the workplace (odds ratio (OR)=2.45, 95% confidence interval (95% CI=2.03-2.96). Those scoring higher were more likely to disagree with the statement that exposure to certain hairdressing-related chemicals is not harmful to human health (OR=0.13, 95% CI=0.03-0.62), and that such chemical exposure does not cause cancer (OR=0.13, 95% CI=0.04-0.40), and were more unlikely to report being too busy to use personal-protective equipment when occupationally using such chemicals (OR=0.45, 95% CI=0.21-0.95). Those participants revealing a low knowledge score with regards to chemicals were also shown to exhibit a poor perception of the long-term harm posed by skin exposure to certain work-related chemicals (OR=2.33, 95% CI=1.10-4.93). Associations between knowledge of chemicals and preventive measures, however, were not found in this study.

CONCLUSIONS

Our study's findings support the need to promote primary prevention of potential hazardous chemical exposure by providing a safe occupational environment for hairdressers by means of providing appropriate education and training with regard to safety measures necessary for the safe handling of relevant chemicals.

The incidence of respiratory symptoms in female Swedish hairdressers

BACKGROUND

Airway diseases in hairdressers are a concern. The objective of this investigation is to evaluate the risk for three respiratory symptoms, wheeze, dry cough, and nasal blockage, in hairdressers.

METHODS

A questionnaire on respiratory symptoms, atopy, smoking, and work history was answered by 3,957 female hairdressers and 4,905 women from the general population as referents. Incidence rates (IR) and incidence rate ratios (IRRs) for the three symptoms were estimated.

RESULTS

The IRs of all three studied symptoms were higher in the hairdressers compared with the referents. Smoking modified the effects of cohort affiliation for all three symptoms; the combined effect from hairdressing work and smoking was less than expected. In addition, the effect of cohort affiliation for wheeze was also modified by atopy, and the effect of cohort affiliation for nasal blockage was also modified by calendar year.

CONCLUSIONS

Hairdressing work was associated with increased incidences of respiratory symptoms. Smoking had a negative modifying effect.

Healthy worker effect and changes in respiratory symptoms and lung function in hairdressing apprentices

AIMS

To compare the prevalence and incidence of respiratory symptoms and lung function values between hairdressing apprentices and office apprentices.

METHODS

A total of 322 hairdressing apprentices and 277 office apprentices (controls) were studied. Two cross sectional surveys were conducted in 1994 and 1996/97 with longitudinal follow up for a subgroup of apprentices (191 hairdressing apprentices and 189 office apprentices).

RESULTS

In the initial phase, the prevalence of respiratory symptoms was significantly lower among hairdressing apprentices than among office apprentices. Lung function test results showed significantly higher values for hairdressing apprentices. Non-specific bronchial reactivity was similar in the two groups. In the final phase, results for respiratory symptoms were similar. The incidence of respiratory symptoms was not significantly different between hairdressing apprentices and office apprentices. Subjects who dropped out had lower values for FVC and FEV1 in the initial phase than those who completed the final phase. There was a significant deterioration of FEV1 and FEF25-75% in hairdressing apprentices compared to office apprentices. There was a link between atopy and the incidence of most of the respiratory symptoms (day/night cough, wheezing, dyspnoea, mucosal hyperresponsiveness) and between smoking and the incidence of bronchial hyperreactivity. There was no significant correlation between change in lung function tests and specific hairdressing activities reported at the end of the apprenticeship or with environmental working conditions in hairdressing salons.

CONCLUSIONS

Although a healthy worker effect can be suspected, results showed a significant deterioration of baseline values of lung function tests in the hairdressing apprentice group. However, no clear link was shown between change in lung function tests and specific parameters of occupational activities.

Prevalence and risk factors of occupational asthma among hairdressers in Turkey

This study was designed to evaluate the questionnaire-based prevalence and possible risk factors of occupational asthma among hairdressers in Turkey. We investigated occupational history and respiratory, ocular, dermal, and nasal symptoms using a standardized questionnaire, evaluated worksite pulmonary function tests, and performed allergen skin testing. We then determined asthma risk factors using age- and gender-adjusted logistic regression models. The prevalence of occupational asthma in hairdressers was 14.6%. The odds ratio for hairdressers in a high work intensity group was 3.6 (95% confidence interval, 1.2 to 10.9) with a significant dose-response trend (chi 2 trend = 4.875; P = 0.027). The odds ratio for occupational asthma among workers with atopy was 4.5 (95% confidence interval, 1.2 to 17.2). We also observed an excess risk of occupational asthma with allergic rhinitis and conjunctivitis. Occupational asthma did not differ among subgroups of hairdressers. We observed an important risk of occupational asthma among hairdressers. The most prominent risk factors were work intensity and atopy.

Smoking, respiratory symptoms, and diseases : a comparative study between northern Sweden and northern Finland: report from the FinEsS study

STUDY OBJECTIVES

The influences of different smoking categories on the prevalence of respiratory symptoms, asthma, and chronic bronchitis have been examined in the most northern province of Sweden, Norrbotten, and in Lapland, Finland. The two areas have similar geographic and demographic conditions.

METHODS AND STUDY POPULATION

The study is a part of the FinEsS studies, which are epidemiologic respiratory surveys in progress in Sweden, Finland, and Estonia. A random sample of 20- to 69-years-olds were invited to answer a postal questionnaire about respiratory symptoms, smoking habits, and occupation. In Norrbotten, 8,333 subjects were invited and 7,104 responded (85%). In Lapland, 8,005 were invited and 6,633 responded (83%).

RESULTS

The participation by age and sex was similar in both countries. The prevalence of smokers in Lapland was 32% vs 26% in Norrbotten. Significantly more women than men in Norrbotten were smokers, while the opposite was true for Lapland. Sputum production was the most prevalent symptom in both areas, 25% in Lapland vs 19% in Norrbotten. The prevalence of chronic productive cough was 11% in Lapland and 7% in Norrbotten. Bronchitic symptoms were more prevalent in Lapland among both smokers and nonsmokers. A positive family history of chronic obstructive airway disease together with increased number of consumed cigarettes showed an additive effect for both chronic productive cough and wheezing. The odds ratio (OR) for wheezing during the last 12 months was 3.8 for subjects without a family history of obstructive airway disease who consumed > 14 cigarettes per day compared with nonsmokers, but if the subjects had a family history of obstructive airway disease, the risk for wheezing increased to OR 8.4.

CONCLUSION

Bronchitic symptoms were more common in Finland. The difference remained also after correction for demographic variables including smoking habits, age and socioeconomic group, and family history of obstructive airway disease. Identical methods, sample composition, and the high participation rate contribute to the validity of the results. Air pollution, including environmental tobacco smoke, may contribute to the difference. To explain the difference, further analysis and investigations of social and environmental factors as well as genetic factors are needed.