Prevalence and Population-Attributable Risk for Chronic Airflow Obstruction in a Large Multinational Study.

Rationale: The Global Burden of Disease program identified smoking and ambient and household air pollution as the main drivers of death and disability from chronic obstructive pulmonary disease (COPD). Objectives: To estimate the attributable risk of chronic airflow obstruction (CAO), a quantifiable characteristic of COPD, due to several risk factors. Methods: The Burden of Obstructive Lung Disease study is a cross-sectional study of adults, aged ≥40, in a globally distributed sample of 41 urban and rural sites. Based on data from 28,459 participants, we estimated the prevalence of CAO, defined as a postbronchodilator FEV1-to-FVC ratio less than the lower limit of normal, and the relative risks associated with different risk factors. Local relative risks were estimated using a Bayesian hierarchical model borrowing information from across sites. From these relative risks and the prevalence of risk factors, we estimated local population attributable risks. Measurements and Main Results: The mean prevalence of CAO was 11.2% in men and 8.6% in women. The mean population attributable risk for smoking was 5.1% in men and 2.2% in women. The next most influential risk factors were poor education levels, working in a dusty job for ≥10 years, low body mass index, and a history of tuberculosis. The risk of CAO attributable to the different risk factors varied across sites. Conclusions: Although smoking remains the most important risk factor for CAO, in some areas, poor education, low body mass index, and passive smoking are of greater importance. Dusty occupations and tuberculosis are important risk factors at some sites.

Respiratory tract deposition of inhaled roadside ultrafine refractory particles in a polluted megacity of South-East Asia.

Recent studies demonstrate that Black Carbon (BC) pollution in economically developing megacities remain higher than the values, which the World Health Organization considers to be safe. Despite the scientific evidence of the degrees of BC exposure, there is still a lack of understanding on how the severe levels of BC pollution affect human health in these regions. We consider information on the respiratory tract deposition dose (DD) of BC to be essential in understanding the link between personal exposure to air pollutants and corresponding health effects. In this work, we combine data on fine and ultrafine refractory particle number concentrations (BC proxy), and activity patterns to derive the respiratory tract deposited amounts of BC particles for the population of the highly polluted metropolitan area of Manila, Philippines. We calculated the total DD of refractory particles based on three metrics: refractory particle number, surface area, and mass concentrations. The calculated DD of total refractory particle number in Metro Manila was found to be 1.6 to 17 times higher than average values reported from Europe and the U.S. In the case of Manila, ultrafine particles smaller than 100 nm accounted for more than 90% of the total deposited refractory particle dose in terms of particle number. This work is a first attempt to quantitatively evaluate the DD of refractory particles and raise awareness in assessing pollution-related health effects in developing megacities. We demonstrate that the majority of the population may be highly affected by BC pollution, which is known to have negative health outcomes if no actions are taken to mitigate its emission. For the governments of such metropolitan areas, we suggest to revise currently existing environmental legislation, raise public awareness, and to establish supplementary monitoring of black carbon in parallel to already existing PM10 and PM2.5 measures.

Burden of obstructive lung disease in a rural setting in the Philippines.

BACKGROUND AND OBJECTIVE: The aim of this study was to determine the prevalence of and risk factors associated with COPD in a rural setting in the Philippines. METHODS: The study was conducted in two municipalities in Nueva Ecija province in the Philippines. Using the Burden of Obstructive Lung Disease (BOLD) protocol and study design, non-hospitalized men or women, aged 40years or older, were recruited by multi-stage random sampling procedures. Participants completed questionnaires on respiratory symptoms and exposure to potential risk factors for COPD, including smoking, occupation and exposure to burning of biomass fuel. Spirometry was performed according to American Thoracic Society criteria. RESULTS: Of the 1188 individuals selected for recruitment, 722 had acceptable post-bronchodilator spirometry and were classified according to Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage. The overall prevalence of COPD for all stages was 20.8%. The prevalence of COPD at GOLD Stage I or higher was greater in men compared with women (26.5% vs 15.3%), and increased between the ages of 40 to >70years. Logistic regression analysis showed a significant association between all stages of COPD and farming for >40years (odds ratio (OR) 2.48, 95% confidence interval (CI): 1.43-4.30), use of firewood for cooking for >60years (OR 3.48, 95% CI: 1.57-7.71), a smoking history of ≥20 pack-years (OR 2.86; 95% CI: 1.78-4.60), and a history of tuberculosis (OR 6.31, 95% CI: 2.67-15.0). CONCLUSIONS: The prevalence COPD in a rural community in Nueva Ecija, Philippines was 20.8% for GOLD Stage I or higher, and 16.7% for GOLD Stage II or higher. In addition to smoking history, the use of firewood for cooking, working on a farm and a history of tuberculosis were significantly associated with fixed airflow obstruction, as assessed by spirometry.