Frequent use of household cleaning products is associated with rhinitis in Chinese children.

BACKGROUND: Despite the popular use of household cleaning products worldwide, there is no published study investigating the health effects of these products on rhinitis in children. OBJECTIVE: We sought to investigate the household use of cleaning products and rhinitis patterns in Chinese children. METHODS: A total of 2299 children were recruited from 21 primary schools with wide geographic coverage in Hong Kong. Self-administered questionnaires were completed by parents/guardians to collect detailed information on respiratory symptoms and household use of 14 types of chemical cleaning products, as well as clean water. Students were categorized into 4 mutually exclusive rhinitis patterns (never, occasional, frequent, and persistent). The total chemical burden (TCB) score was used as the exposure indicator by calculating the total time of exposure to the 14 cleaning products. Multinomial logistic regression was used to assess the relationship between rhinitis patterns and the use of household cleaning products. RESULTS: Every 10-unit increment of TCB score was associated with an increase in the odds of occasional (odds ratio [OR], 1.21; 95% CI, 1.05-1.41), frequent (OR, 1.36; 95% CI, 1.13-1.60), and persistent (OR, 1.21; 95% CI, 1.01-1.56) rhinitis after adjustment for a wide range of potential confounders. Compared with the children within the lowest tertile of TCB scores, the adjusted ORs of occasional, frequent, and persistent rhinitis in children within the highest tertile were 1.29 (95% CI, 1.01-1.65), 1.97 (95% CI, 1.40-2.76), and 1.67 (95% CI, 1.10-2.54), respectively. CONCLUSION: Frequent use of chemical cleaning products at home is associated with an increase in the odds of rhinitis in Chinese primary school children.

Who is more vulnerable to death from extremely cold temperatures? A case-only approach in Hong Kong with a temperate climate.

The short-term effects of ambient cold temperature on mortality have been well documented in the literature worldwide. However, less is known about which subpopulations are more vulnerable to death related to extreme cold. We aimed to examine the personal characteristics and underlying causes of death that modified the association between extreme cold and mortality in a case-only approach. Individual information of 197,680 deaths of natural causes, daily temperature, and air pollution concentrations in cool season (November-April) during 2002-2011 in Hong Kong were collected. Extreme cold was defined as those days with preceding week with a daily maximum temperature at or less than the 1st percentile of its distribution. Logistic regression models were used to estimate the effects of modification, further controlling for age, seasonal pattern, and air pollution. Sensitivity analyses were conducted by using the 5th percentile as cutoff point to define the extreme cold. Subjects with age of 85 and older were more vulnerable to extreme cold, with an odds ratio (OR) of 1.33 (95 % confidence interval (CI), 1.22-1.45). The greater risk of extreme cold-related mortality was observed for total cardiorespiratory diseases and several specific causes including hypertensive diseases, stroke, congestive heart failure, chronic obstructive pulmonary disease (COPD), and pneumonia. Hypertensive diseases exhibited the greatest vulnerability to extreme cold exposure, with an OR of 1.37 (95 % CI, 1.13-1.65). Sensitivity analyses showed the robustness of these effect modifications. This evidence on which subpopulations are vulnerable to the adverse effects of extreme cold is important to inform public health measures to minimize those effects.

Consumption of salted meat and its interactions with alcohol drinking and tobacco smoking on esophageal squamous-cell carcinoma.

Etiology of esophageal cancer has not yet been clearly documented, especially in high-risk regions. To evaluate the association between salted meat intake and esophageal squamous-cell carcinoma (ESCC) and to explore its joint effects with alcohol drinking and smoking, a population-based case-control study was conducted in a high ESCC risk area in China, including 942 incident ESCC cases and 942 age- and sex-matching controls. A validated food frequency questionnaire was used to collect information on dietary factors, alcohol drinking and tobacco smoking. Conditional logistic regressions were applied to estimate the association between salted meat intake and ESCC and its interactions with alcohol drinking and smoking, with adjustment for other confounders, including total energy intake. Salted meat intake was associated with an increased risk of ESCC, showing an exposure-response relationship (p for trend <0.001). Consumption of 50 g salted meat per week was related to an increased risk by 18% (odds ratio = 1.18, 95% confidence interval: 1.13-1.23). Salted meat in combination with either alcohol drinking or smoking had a greater risk than salted meat alone, which was more than additive. The strongest association was seen in the combination of all the three factors, particularly at the highest level of salted meat intake (odds ratio = 29.27, 95% confidence interval: 13.21-64.89). Salted meat intake is strongly associated with ESCC and its interactions with alcohol drinking and/or smoking highlights the significance of reducing salted meat intake among smokers and drinkers with respect to ESCC prevention.

Differential distributed lag patterns of source-specific particulate matter on respiratory emergency hospitalizations.

While different emission sources and formation processes generate mixtures of particulate matter (PM) with different physicochemical compositions that may differentially affect PM toxicity, evidence of associations between PM sources and respiratory events is scarce. We estimated PM10 sources contributed from 19 chemical constituents by positive matrix factorization, and examined association of short-term sources exposure with emergency respiratory hospitalizations using generalized additive models for single- and distributed lag periods. PM10 contributions from eight sources were identified. Respiratory risks over a consecutive 6-day exposure period were the highest for vehicle exhaust [2.01%; 95% confidence interval (CI): 1.04, 2.99], followed by secondary sulfate (1.59%; 95% CI: 0.82, 2.37). Vehicle exhaust, regional combustion, and secondary nitrate were significantly associated with 0.93%-2.04% increase in respiratory hospitalizations at cumulative lag2-5; significant associations of aged sea salt (1.2%; 95% CI: 0.63, 1.78) and soil/road dust (0.42%; 95% CI: 0.03, 0.82) were at lag0-1. Some effect estimates were no longer significant in two-pollutant models adjusting for PM10; however, a similar temporal pattern of associations remains. Differential lag associations of respiratory hospitalizations with PM10 sources were indicated, which may reflect the different particle size fractions that sources tend to emit. Findings may have potential biological and policy implications.

Ambient carbon monoxide and the risk of hospitalization due to chronic obstructive pulmonary disease.

Data from recent experimental and clinical studies have indicated that lower concentrations of inhaled carbon monoxide might have beneficial antiinflammatory effects. Inhaled carbon monoxide has the potential to be a therapeutic agent for chronic obstructive pulmonary diseases (COPD). However, population-based epidemiologic studies of environmentally relevant carbon monoxide exposure have generated mixed findings. We conducted a time-series study in Hong Kong to estimate the association of short-term exposure to ambient carbon monoxide with emergency hospitalizations for COPD. We collected daily emergency hospital admission data and air pollution data from January 2001 to December 2007. We used log-linear Poisson models to estimate the associations between daily hospital admissions for COPD and the average daily concentrations of carbon monoxide while controlling for the traffic-related co-pollutants nitrogen dioxide and particulate matter with an aerodynamic diameter less than 2.5 µm. Results showed that ambient carbon monoxide was negatively associated with the risk of hospitalizations for COPD. After adjustment for levels nitrogen dioxide or particulate matter with an aerodynamic diameter less than 2.5 µm, the negative associations of carbon monoxide with COPD hospitalizations became stronger. The risk estimates were similar for female and male subjects. In conclusion, short-term exposure to ambient carbon monoxide was associated with a decreased risk of hospitalization for COPD, which suggests that carbon monoxide exposure provides some acute protection of against exacerbation of COPD.

Coarse particulate matter associated with increased risk of emergency hospital admissions for pneumonia in Hong Kong.

BACKGROUND: Epidemiological research on the effects of coarse particles (PMc, particulate matter between 2.5 and 10 µm in aerodynamic diameter) on respiratory morbidity is sparse and inconclusive. Pneumonia is an inflammatory condition of lung caused by infections, which may be triggered and exacerbated by PMc exposure. AIM: To estimate the effect of PMc on emergency hospital admissions for pneumonia after controlling for PM(2.5) and gaseous pollutants. METHOD: PMc concentrations were estimated by subtracting PM(2.5) from PM(10) measurements in each of the 10 air monitoring stations from January 2011 to December 2012 in Hong Kong and then citywide daily average concentrations of PMc were computed from the 10 stations. Generalised additive Poisson models were used to examine the relationship between PMc and daily emergency hospital admissions for pneumonia, adjusting for PM(2.5) and gaseous pollutants (NO(2), SO(2) and O(3)). Subgroup analyses by gender and age were also performed to identify the most susceptible subpopulations. RESULTS: PMc and PM(2.5) were significantly associated with emergency pneumonia hospitalisations. Every 10 µg/m(3) increment of PMc in the past 4 days (lag0-lag3) was associated with a 3.33% (95% CI 1.54% to 5.15%) increase in emergency hospitalisations for pneumonia. The effect estimates of PMc were robust to the adjustment of PM(2.5), NO(2) or SO(2), but attenuated on the inclusion of O(3) in the model. Women, children and older people might be more vulnerable to PMc exposure. CONCLUSIONS: Short-term PMc exposure is associated with emergency hospitalisations for pneumonia in Hong Kong. Air quality regulation specifically for PMc might be considered.

Ambient carbon monoxide associated with reduced risk of hospital admissions for respiratory tract infections.

RATIONALE: Recent experimental and clinical studies suggest that exogenous carbon monoxide (CO) at lower concentrations may have beneficial effects under certain circumstances, whereas population-based epidemiologic studies of environmentally relevant CO exposure generated mixed findings. OBJECTIVES: To examine the acute effects of ambient CO on respiratory tract infection (RTI) hospitalizations. METHODS: A time series study was conducted. Daily emergency hospital admission and air pollution data in Hong Kong were collected from January 2001 to December 2007. Log-linear Poisson models were used to estimate the associations between daily hospital admissions for RTI and daily average concentrations of CO across three background air monitoring stations and three roadside stations, respectively, controlling for other traffic-related copollutants. MEASUREMENTS AND MAIN RESULTS: CO concentrations were low during the study period with a daily average of 0.6 ppm in background stations and 1.0 ppm in roadside stations. Negative associations were found between ambient CO concentrations and daily hospital admissions for RTI. One ppm increase in background CO at lag 0-2 days was associated with -5.7% (95% confidence interval, -9.2 to -2.1) change in RTI admissions from the whole population according to single-pollutant model; the negative association became stronger when nitrogen dioxide or particulate matter with aerodynamic diameter less than 10 µm was adjusted for in two-pollutant models. The negative association seemed to be stronger in the adults than in the children and elderly. CONCLUSIONS: Short-term exposure to ambient CO was associated with decreased risk of hospital admissions for RTI, suggesting some acute protective effects of low ambient CO exposure on respiratory infection.

Effectiveness of participatory training for prevention of musculoskeletal disorders: a randomized controlled trial.

PURPOSE: Health and safety training program has been applied to prevent work-related musculoskeletal disorders (MSDs) in workplace. We evaluated the effectiveness of participatory training and didactic training programs on MSD prevention among frontline workers in Shenzhen, China. METHODS: The authors randomly assigned 918 workers from intervention factories to receive participatory training (intervention group), and 907 workers from intervention factories and 1,654 workers from control factories to receive didactic training (control_1 group, control_2 group, respectively) from June 1, 2008 to November 30, 2009. Participants were asked to report experience of ache, pain or discomfort in 10 body parts at baseline and 1 year after training. Data were analyzed to compare the MSD prevalence 1 year before and 1 year after training in different groups from 2009 to 2010. RESULTS: The follow-up rate was 61 % (2,120/3,479) at 1 year after training. In the year after training, there were no statistically significant changes in the proportion of workers who reported MSD in any body part. MSD prevalence rates in the intervention group reduced from 16.8 to 9.9 % for lower extremities (χ(2) = 13.102, p < 0.001) and from 12.9 to 8.3 % (χ(2) = 9.433, p = 0.002) for wrist and finger at 1 year after training. However, the rates did not change significantly for upper back, lower back, neck, shoulder and elbow in the intervention group and for all 10 body parts in two control groups. CONCLUSIONS: Overall, the training programs did not seem to prevent the occurrence of MSD among frontline workers. However, participatory training might be effective to reduce MSD in the lower extremities and wrist and finger.

Increasing trend of primary NO(2) exhaust emission fraction in Hong Kong.

Despite the successful reduction in roadside NO( x ) levels, no such decrease has been detected in roadside NO(2) concentration in Hong Kong. One underlying cause could be the rising primary NO(2) fraction of the total emission of NO( x ). Primary NO(2) can be particularly detrimental to Hong Kong because a large fraction of the population are exposed to the traffic-related primary pollutants in the street canyons formed by congested high-rise buildings. In this study, hourly mean concentration data for roadside nitrogen oxides (NO( x )), nitrogen dioxide (NO(2)), and background ozone (O(3)) were used to estimate the mean primary NO(2) fraction from vehicle exhausts in Hong Kong. An overall increasing trend was observed for the primary NO(2) fraction (f-NO(2)) values in all the three roadside air monitoring sites. The primary NO(2) as a fraction of total NO( x ) (f-NO(2)) increased approximately from 2% in 1998 to 13% in 2008 in Hong Kong. The two particular periods of rising f-NO(2) coincided with the two implementation periods of the diesel retrofit programs for the light-duty vehicles and heavy-duty vehicles. Future vehicle emission control strategies should target not only total NO( x ) but also primary NO(2). Health benefit or disease burden estimates should be taken into account and updated in the process of policy planning and evaluation.

Possible role of aerosol transmission in a hospital outbreak of influenza.

BACKGROUND: We examined the role of aerosol transmission of influenza in an acute ward setting. METHODS: We investigated a seasonal influenza A outbreak that occurred in our general medical ward (with open bay ward layout) in 2008. Clinical and epidemiological information was collected in real time during the outbreak. Spatiotemporal analysis was performed to estimate the infection risk among patients. Airflow measurements were conducted, and concentrations of hypothetical virus-laden aerosols at different ward locations were estimated using computational fluid dynamics modeling. RESULTS: Nine inpatients were infected with an identical strain of influenza A/H3N2 virus. With reference to the index patient's location, the attack rate was 20.0% and 22.2% in the "same" and "adjacent" bays, respectively, but 0% in the "distant" bay (P = .04). Temporally, the risk of being infected was highest on the day when noninvasive ventilation was used in the index patient; multivariate logistic regression revealed an odds ratio of 14.9 (95% confidence interval, 1.7-131.3; P = .015). A simultaneous, directional indoor airflow blown from the "same" bay toward the "adjacent" bay was found; it was inadvertently created by an unopposed air jet from a separate air purifier placed next to the index patient's bed. Computational fluid dynamics modeling revealed that the dispersal pattern of aerosols originated from the index patient coincided with the bed locations of affected patients. CONCLUSIONS: Our findings suggest a possible role of aerosol transmission of influenza in an acute ward setting. Source and engineering controls, such as avoiding aerosol generation and improving ventilation design, may warrant consideration to prevent nosocomial outbreaks.

Risk of second primary malignancies following nasopharyngeal carcinoma in Hong Kong.

Nasopharyngeal carcinoma (NPC) is rare in most of the world but common among southeast Asians. Since NPC is usually diagnosed at relatively young ages and most patients now survive, the issue of second primary tumors (SPTs) has become important. Previous studies of SPTs among NPC survivors have given conflicting results. Data on patients with NPC diagnosed between 1996 and 2002 were abstracted from the medical records of two Hong Kong oncology centers. SPT incidence in these patients was compared to that of Hong Kong's general population using standardized incidence ratios (SIR). Eight-four patients were observed to have at least 1 SPT and 92 total additional cancers (SIR = 1.93, 95% CI = 1.55-2.37). The excess risk was greater for women and patients under 40 at diagnosis. Significant excesses were found for tongue, lung, nasal and middle ear, and brain cancers. The pattern of sites at which the greatest excess risk occurred is consistent with the hypothesis that much of the excess is due to treatment effects. The greater excess risk among patients diagnosed before 40 points to possible genetic influences. More research is needed to determine the reasons for greater excess risk among women.

Previous pulmonary disease and family cancer history increase the risk of lung cancer among Hong Kong women.

Chinese women in Hong Kong have among the highest incidence and mortality of lung cancer in the world, in spite of a low prevalence of smoking. We carried out this population-based case-control study to evaluate the associations of previous lung disease and family cancer history with the occurrence of lung cancer among them. We selected 212 cases that were newly diagnosed with primary lung cancer, and randomly sampled 292 controls from the community, frequency matched by age group. All the cases and controls were lifetime nonsmokers. We estimated the main effects of preexisting asthma, pulmonary tuberculosis, pneumonia, chronic bronchitis, and family lung/all cancer history, using unconditional logistic regression, accounting for various potential risk factors and confounders. All of the previous lung diseases, except chronic bronchitis, were related to an elevated risk for lung cancer, and the association with asthma was significant. Those who had more than one previous lung disease tended to be at higher risk than those with only one of them. Positive family history of any cancer was associated with over 2-fold risk than negative family history. The joint effect of positive history of previous pulmonary diseases and positive family cancer history appeared to be additive, indicating the two factors acted independently. The results support an etiological link of preexisting lung disease and family cancer history to the risk of lung cancer.

Dose-response relationship between cooking fumes exposures and lung cancer among Chinese nonsmoking women.

The high incidence of lung cancer among Chinese females, despite a low smoking prevalence, remains poorly explained. Cooking fume exposure during frying could be an important risk factor. We carried out a population-based case-control study in Hong Kong. Cases were Chinese female nonsmokers with newly diagnosed primary lung cancer. Controls were female nonsmokers randomly sampled from the community, frequency matched by age groups. Face-to-face interviews were conducted using a standardized questionnaire. The "total cooking dish-years," categorized by increments of 50, was used as a surrogate of cooking fumes exposure. Multiple unconditional logistic regression was used to estimate the odds ratios (OR) for different levels of exposure after adjusting for various potential confounding factors. We interviewed 200 cases and 285 controls. The ORs of lung cancer across increasing levels of cooking dish-years were 1, 1.17, 1.92, 2.26, and 6.15. After adjusting for age and other potential confounding factors, the increasing trend of ORs with increasing exposure categories became clearer, being 1, 1.31, 4.12, 4.68, and 34. The OR of lung cancer was highest for deep-frying (2.56 per 10 dish-years) followed by that of frying (1.47), and stir-frying had the lowest OR (1.12) among the three methods. Cumulative exposure to cooking by means of any form of frying could increase the risk of lung cancer in Hong Kong nonsmoking women. Practical means to reduce exposures to cooking fumes should be given top priority in future research.

Evidence of airborne transmission of the severe acute respiratory syndrome virus.

BACKGROUND: There is uncertainty about the mode of transmission of the severe acute respiratory syndrome (SARS) virus. We analyzed the temporal and spatial distributions of cases in a large community outbreak of SARS in Hong Kong and examined the correlation of these data with the three-dimensional spread of a virus-laden aerosol plume that was modeled using studies of airflow dynamics. METHODS: We determined the distribution of the initial 187 cases of SARS in the Amoy Gardens housing complex in 2003 according to the date of onset and location of residence. We then studied the association between the location (building, floor, and direction the apartment unit faced) and the probability of infection using logistic regression. The spread of the airborne, virus-laden aerosols generated by the index patient was modeled with the use of airflow-dynamics studies, including studies performed with the use of computational fluid-dynamics and multizone modeling. RESULTS: The curves of the epidemic suggested a common source of the outbreak. All but 5 patients lived in seven buildings (A to G), and the index patient and more than half the other patients with SARS (99 patients) lived in building E. Residents of the floors at the middle and upper levels in building E were at a significantly higher risk than residents on lower floors; this finding is consistent with a rising plume of contaminated warm air in the air shaft generated from a middle-level apartment unit. The risks for the different units matched the virus concentrations predicted with the use of multizone modeling. The distribution of risk in buildings B, C, and D corresponded well with the three-dimensional spread of virus-laden aerosols predicted with the use of computational fluid-dynamics modeling. CONCLUSIONS: Airborne spread of the virus appears to explain this large community outbreak of SARS, and future efforts at prevention and control must take into consideration the potential for airborne spread of this virus.