Respiratory infections among junior high school students in upper northern Thailand: The role of building dampness and mould, biomass burning and outdoor relative air humidity (RH).

BACKGROUND: Few studies exist on environmental risk factors for respiratory infections in Thai school children. AIM: To study associations between home and outdoor environment and respiratory infections among school children in Northern Thailand in dry and wet season. METHODS: A repeated questionnaire survey among the children (N = 1159). Data on ambient temperature and relative air humidity (RH) and PM10 and ozone was collected from nearby monitoring stations. We used logistic regression to calculate odds ratios (OR). RESULTS: 14.1% had current respiratory infections (last 7 days), 32.1% had any respiratory infection last 3 months, and 26.1% had any respiratory infection last 12 months with antibiotic treatment. Students with diagnosed allergy (7.7%) and diagnosed asthma (4.7%) had more often respiratory infections (ORs 1.40-5.40; p < 0.05). Current respiratory infections were more common in dry (18.1%) than in wet season (10.4%) (p < 0.001) and was associated with indoor mould (OR 2.16; p = 0.024) and outdoor RH (OR 1.34 per 10% RH; p = 0.004.) in the total material. In wet season, mould (OR 2.32; p = 0.016), window pane condensation (OR 1.79; p = 0.050), water leakage (OR 1.82; p = 0.018), environmental tobacco smoke (ETS) (OR 2.34; p = 0.003) and outdoor RH (OR 2.70 per 10% RH; p = 0.01) were risk factors for current respiratory infections. In dry season, mould (OR 2.64; p = 0.004) and outdoor RH (OR 1.34 per 10% RH; p = 0.046) were associated with current respiratory infections. Irrespectively of season, biomass burning inside or outside the home was a risk factor for respiratory infections (ORs 1.32-2.34; p < 0.05). Living in a wooden house decreased the risk of respiratory infections (OR 0.56: p = 0.006). CONCLUSIONS: Dry season, high outdoor RH, household dampness, indoor mould and ETS can increase childhood respiratory infections. Living in a traditional wooden house can reduce respiratory infections, possibly due to better natural ventilation. Smoke from biomass burning can increase childhood respiratory infections in northern Thailand.

Asthma and rhinitis in wet and dry season among students in upper Northern Thailand: the role of building dampness and household air pollution.

We investigated associations between domestic exposure and respiratory health in students inNorthern Thailand in wet and dry season (1159 participants), calculating odds ratios (OR) with 95% confidence intervals (CI) by multilevel logistic regression. Totally 6.0% had wheeze, 23.0% dyspnoea, 4.0% current asthma, 54.6% rhinitis and 31.5% rhinoconjunctivitis. Girls had less wheeze (OR 0.66; 95% CI 0.43-1.00) and current asthma (OR 0.32; 95% CI 0.19-0.54). Water leakage was associated with wheeze (OR 2.35; 95% CI 1.09-5.06), dyspnea (OR 2.00; 95% CI 1.24-3.23) and rhinoconjunctivitis (OR 1.62; 95% CI 1.11-2.38). Mould was associated with rhinitis (OR 1.89; 95% CI 1.06-3.38). Window pane condensation was associated with wheeze (OR 2.60; 95% CI 1.13-5.98) and rhinoconjunctivitis (OR 1.70; 95% CI 1.08-2.67). Biomass burning was associated with wheeze, dyspnoea, rhinitis and rhinoconjunctivitis. In conclusion, household dampness and pollution from domestic biomass burning can increase asthma symptoms and rhinitis symptoms in students in northern Thailand.

Fractional exhaled nitric oxide (FeNO) in students in Northern Thailand: associations with respiratory symptoms, diagnosed allergy and the home environment.

OBJECTIVE: There are few studies on fractional exhaled nitric oxide (FeNO) among children in subtropical areas. We studied associations between FeNO and respiratory symptoms, reported diagnosed allergies and indoor and outdoor environmental factors in first grade junior high school students (N = 270) in upper northern Thailand. METHODS: Data on demographics, health and home environment were collected by a questionnaire distributed in dry season (February-March 2018). FeNO was measured when the research team visited the school. Daily outdoor pollution data (PM10 and ozone) were collected from the nearest monitoring station 3 days (lag 3) and 7 days (lag 7) before the FeNO measurements. Two-level (student, school) linear mixed models were used to analyze associations, adjusting for gender and family education level. RESULTS: In total, 29.6% had elevated FeNO level (>20 ppb) and 7.8% reported any allergy diagnosed by a doctor. Male gender (p = 0.02), diagnosed allergy (p = 0.001), especially to cat (p = 0.001) and house dust mite (HDM) allergies (p = 0.001) were associated with FeNO. Eye symptoms (p = 0.01), rhinitis symptoms (p = 0.03) and dyspnea (p = 0.05) in the last 3 days were associated with FeNO. Household indoor mold (p = 0.03), gas cooking (p = 0.03) and PM10 (lag 3 and lag 7) were negatively (protective) associated with FeNO. CONCLUSIONS: Diagnosed allergy, especially to cat and HDM, can be associated with increased FeNO. Indoor mold and gas cooking can be associated with lower FeNO. Ocular, nasal and dyspnea symptoms reported by students in dry season in northern Thailand can be associated with FeNO, a biomarker of Th2 driven airway inflammation.

Associations between indoor environment in residential buildings in wet and dry seasons and health of students in upper northern Thailand.

We performed a repeated questionnaire study on home environment and health (six medical symptoms) in 1159 junior high school students (age 12.8 ± 0.7 years) in upper northern Thailand in wet and dry seasons. Data on outdoor temperature, relative humidity (RH), and air pollution were collected from nearest monitoring station. Odds ratios (OR) were calculated by multi-level logistic regression. Most common symptoms were rhinitis (62.5%), headache (49.8%), throat (42.8%), and ocular symptoms (42.5%). Ocular symptoms were more common at lower RH and rhinitis more common in dry season. Water leakage (28.2%), indoor mold (7.1%), mold odor (4.1%), and windowpane condensation (13.6%) were associated with all six symptoms (ORs: 1.3-3.5). Other risk factors included cat keeping, environmental tobacco smoke (ETS), other odor than mold odor, gas cooking, and cooking with biomass fire. Biomass burning inside and outside the home for other reasons than cooking was associated with all six symptoms (ORs: 1.5-2.6). Associations between home environment exposure and rhinitis were stronger in wet season. In conclusion, dampness-related exposure, windowpane condensation, cat keeping, ETS, gas cooking, and biomass burning can impair adolescent health in upper northern Thailand. In subtropical areas, environmental health effects should be investigated in wet and dry seasons.

Health Risk Assessment of Heavy Metals in Indoor Household Dust in Urban and Rural Areas of Chiang Mai and Lamphun Provinces, Thailand.

Indoor exposure to heavy metals poses human health risks worldwide, but study reports from Thailand are still limited, particularly in rural and urban areas. We measured the heavy metals in a hundred indoor household dust samples collected from urban and rural areas in Chiang Mai and Lamphun provinces and found a significantly higher concentration of As in rural areas and Cd in urban areas with industrial activities. The source identification of the heavy metals showed significant enrichment from traffic emissions, paint, smoking, and mixed sources with natural soil. From health risk assessment models, children were more vulnerable to noncarcinogenic risks (HI = 1.45), primarily via ingestion (HQ = 1.39). Lifetime cancer risks (LCRs) due to heavy metal exposure were found in adults (LCR = 5.31 × 10-4) and children (LCR = 9.05 × 10-4). The cancer risks from As were higher in rural areas via ingestion, while Cr and Ni were higher in urban areas via inhalation and ingestion, respectively. This study estimated that approximately 5 out of 10,000 adults and 9 out of 10,000 children among the population may develop cancer in their lifetime from exposure to indoor heavy metals in this region.

Estimation of lung cancer deaths attributable to indoor radon exposure in upper northern Thailand.

Radon exposure is the second leading cause of lung cancer, after smoking. In upper northern Thailand (UNT), lung cancer incidence was frequently reported by Thailand National Cancer Institute. Besides smoking, radon exposure may also influence the high lung cancer incidence in this region. Indoor radon concentrations were measured in 192 houses in eight provinces of UNT. Indoor radon concentrations ranged from 11 to 405 Bq m-3 and estimated annual effective dose ranged from 0.44 to 12.18 mSv y-1. There were significant differences in indoor radon concentrations between the houses of lung cancer cases and healthy controls (p = 0.033). We estimated that 26% of lung cancer deaths in males and 28% in females were attributable to indoor radon exposure in this region. Other factors influencing indoor radon levels included house characteristics and ventilation. The open window-to-wall ratio was negatively associated with indoor radon levels (B = -0.69, 95% CI -1.37, -0.02) while the bedroom location in the house and building material showed no association. Indoor radon hence induced the fractal proportion of lung cancer deaths in UNT.