Association between air pollution and general practitioner visits for respiratory diseases in Hong Kong.

BACKGROUND: Few studies have explored the relation between air pollution and general practitioner (GP) consultations in Asia. Clinic attendance data from a network of GPs were studied, and the relationship between daily GP consultations for upper respiratory tract infections (URTI) and non-URTI respiratory diseases and daily air pollutant concentrations measured in their respective districts was examined. METHODS: A time series study was performed in 2000-2002 using data on daily patient consultations in 13 GP clinics distributed over eight districts. A Poisson regression model was constructed using the generalised additive model approach for each GP clinic, and associations with daily numbers of first visits for URTI were sought for daily concentrations of the following air pollutants: SO(2), NO(2), O(3), PM(10,) and PM(2.5). A summary relative risk of first visits to the GP for URTI per unit increase in concentration for each air pollutant was derived using a random effect model. First visits for non-URTI respiratory diseases were analysed in three GP clinics. RESULTS: Significant associations were observed between first visits for URTI and an increase in the concentrations of NO(2), O(3), PM(10), and PM(2.5). The excess risk was highest for NO(2) (3.0%), followed by O(3) (2.5%), PM(2.5) (2.1%), and PM(10) (2.0%). Similar associations with these air pollutants were found for non-URTI respiratory diseases. CONCLUSIONS: These results provide further evidence that air pollution contributes to GP visits for URTI and non-URTI respiratory diseases in the community.

Household gas cooking: a risk factor for respiratory illnesses in preschool children.

AIMS: To explore the association of household gas cooking and respiratory illnesses in preschool children and their relation to outdoor air pollution. METHODS: Cross-sectional study among households that used gas stoves for cooking in two housing estates with contrasting air qualities in Hong Kong. A structured questionnaire was administered to parents of 426 children aged 0-6 years on their exposure to gas cooking and passive smoking, and the prevalence of respiratory illnesses. RESULTS: A total of 111 children (26.1%) were reported to have one or more respiratory illnesses (allergic rhinitis, asthma, bronchitis, sinusitis, and pneumonia). Of these, 21 (18.9%), 41 (36.9%), and 49 (44.1%) children were from households that cooked once, twice, and three times a day with gas. Hierarchical logistic regression models adjusting for socioeconomic, demographic, and indoor risk factors including passive smoking showed that household gas cooking was positively associated with respiratory illnesses. There was a dose-response relation between the frequency of gas cooking and the prevalence of respiratory illnesses in the estate with lower outdoor air pollution (OR = 6.1 and 3.2 respectively, for cooking three and two meals a day, compared to one meal a day). This relation was not observed in the more polluted estate. The association between the presence of a cigarette smoker in the household and the prevalence of respiratory illnesses was not significant. CONCLUSIONS: As gas cooking is common in urban households, the findings could have important public health implications.

Agreement between hearing thresholds measured in non-soundproof work environments and a soundproof booth.

AIMS: To study the agreement between audiometric test results measured in non-soundproof environments at the worksite, and in a soundproof booth. METHODS: In a cross sectional prevalence study on noise induced hearing loss, 885 transport workers whose hearing thresholds were measured by a standard audiometric test method in non-soundproof environments at the worksite were identified to have some hearing loss (>25 dB), and were retested in a soundproof booth. RESULTS: At 4-8 KHz, the mean of the absolute differences in hearing threshold obtained by these two methods was 2 dB or less. When the proportions of hearing loss (> or =30 dB for any frequencies at 3-8 KHz, or > or =90 dB for three low frequencies at 0.5-2 KHz, or > or =90 dB for three high frequencies at 3-6 KHz) were compared, considerable differences existed. A much better agreement was obtained when the criteria for hearing loss as measured in the field test under non-soundproof conditions were relaxed by 5 dB. At 4 KHz, the difference between the proportion of subjects with hearing loss as measured in the field and that as measured in the booth was the smallest. The kappa statistic was highest at 3 and 4 KHz. CONCLUSIONS: Audiometric test results conducted in non-soundproof environments in the field are comparable to those obtained in a soundproof environment among transport workers with a hearing loss of >25 dB. The hearing threshold at 4 KHz appears suitable for the estimation of the prevalence of hearing loss when appropriate adjustments are made in the diagnostic criteria.

Associations between daily mortalities from respiratory and cardiovascular diseases and air pollution in Hong Kong, China.

OBJECTIVE: To investigate the association between ambient concentrations of air pollutants and respiratory and cardiovascular mortalities in Hong Kong. METHODS: Retrospective ecological study. A Poisson regression of concentrations of daily air pollutants on daily mortalities for respiratory and cardiovascular diseases in Hong Kong from 1995 to the end of 1998 was performed using the air pollution and health: the European approach (APHEA) protocol. The effects of time trend, seasonal variations, temperature, and humidity were adjusted. Autocorrelation and overdispersion were corrected. Daily concentrations of nitrogen dioxide (NO2), sulphur dioxide (SO2), ozone (O3), and particulate matter <10 microm in aerodynamic diameter (PM10) were averaged from eight monitoring stations in Hong Kong. Relative risks (RRs) of respiratory and cardiovascular mortalities (per 10 microg/m(3) increase in air pollutant concentration) were calculated. RESULTS: Significant associations were found between mortalities for all respiratory diseases and ischaemic heart diseases (IHD) and the concentrations of all pollutants when analysed singly. The RRs for all respiratory mortalities (for a 10 microg/m(3) increase in the concentration of a pollutant) ranged from 1.008 (for PM10) to 1.015 (for SO2) and were higher for chronic obstructive pulmonary diseases (COPD) with all pollutants except SO2, ranging from 1.017 (for PM10) to 1.034 (for O3). RRs for IHD ranged from 1.009 (for O3) to 1.028 (for SO2). In a multipollutant model, O3 and SO2 were significantly associated with all respiratory mortalities, whereas NO2 was associated with mortality from IHD. No interactions were detected between any of the pollutants or with the winter season. A dose-response effect was evident for all air pollutants. Harvesting was not found in the short term. CONCLUSIONS: Mortality risks were detected at current ambient concentrations of air pollutants. The associations with the particulates and some gaseous pollutants when analysed singly were consistent with many reported in temperate countries. PM10 was not associated with respiratory or cardiovascular mortalities in multipollutant analyses.