Objective: A prospective study of newly exposed cotton workers was performed to investigate the natural history of respiratory symptoms and lung function changes. Methods: A total of 157 workers ...naive to cotton dust exposure were investigated by questionnaire, spirometry, and skin tests. They were examined before employment (baseline) and at the end of the first week, and the first, third, sixth, and 12th month after starting work. Acute airway response was defined as either a cross-first-shifl or a cross-week fall in forced expiratory volume in one second (FEV₁). The longitudina change of lung function over the year was aho calculated. Five hundred seventy-two personal dust sampling and 191 endotoxin measurements were performed to assess th exposure. Results: Forty percent of workers reported work-related symptoms in the fi week of the study. Smoking, endotoxin, and dust concentrations were nsk factors for all work-related symptoms. Acute airway responses were witnessed after immediate exposure. Female status was the only factor found to be predictive of acute airway response. The mean longitudinal fall in FEV₁ at 1 year was 65.5 mL (standard error = 37.2). Age, early respiratory symptoms, and early fall in cross-week FEV₁. were found to predict the 12-month fall in FEV₁. Cross-first-shift and cross-week falh FEV₁ reduced in magnitude during the course of the study. Conclusions: This study of workers naive to cotton dust exposure has demonstrated that respiratory symptoms and acute airway responses develop early following first exposure, and a tolerance effe develops in those workers with the continued exposure. Current smoking and increasing exposure predicts the development of work-related lower respiratory tract symptoms, while early symptoms and acute airway changes across the working week predict the longitudinal loss of lung function at 1 year.
The objective of this article is to analyze the design, implementation and evaluation experience of the MOOC Escribir para convencer in edX in order to contribute to the discussion about new ways of ...teaching and learning in digital contexts. The article presents the systematization of the instructional design under the ADDIE model, integrated with the principles of the Ignatian Pedagogical Paradigm. A descriptive study, which included quantitative information taken from the edX Insights tool and satisfaction surveys applied in the course, and qualitative information collected through the forums of the units. The participants had an adequate performance in individual activities and automatic feedback (questionnaires) and a lower participation in collaborative activities. As in other MOOCs, there is a decrease in the number of participants involved as the cours passes. The instructional design of this type of courses confronts some challenges, among them the transformations in the roles of the teachers regarding direct mediation, and of the students, as they require autonomy, commitment and openness to the collaborative construction of knowledge. Despite these challenges, instructional design contributes to the effectiveness of MOOCs and their effectiveness as an alternative of teaching in everyday and academic contexts that contribute to the generation of global and digital citizens.
The stricter guidelines for fine particles PM2.5 recently published by the World Health Organization also motivate smaller cities to assess the exposure levels. In this study, PM2.5 was assessed in ...the municipality of Vijes, an important lime production center in the Cauca River Valley, Colombia. The main objective was to determine PM2.5 concentration levels in the urban background of the city and to estimate the contribution from industrial sources located west of the urbanized area. The assessment of PM2.5 concentrations in a city without fixed air quality monitors, meteorological stations, and information on emission sources, was designed to be expedient and possible to perform with a very restricted budget. Four low-cost optical sensors and one low-cost meteorological station were installed during two separate campaigns, each three to four months long. The PM2.5 measurements were analyzed with the support of meteorological data and dispersion modeling. Mean levels of PM2.5 in the urban background were found to be below the Colombian limit value of 25 µg m–3, in the range of 14 to 19 µg m–3, and with lower levels in the city center. The monitor located in the westernmost urban area, closest to the industrial plants, registered a high 24-h mean level close to the national limit value. The industrial contribution to long-term PM2.5 concentrations in the urban background of Vijes was estimated to be within a maximum of 6 µg m–3, i.e., a minor fraction of the monitored PM2.5 mean levels in the urban background. The dominating part of the PM2.5 concentrations could be attributed to other anthropogenic sources within or east of Vijes, as well as originating from the regional background concentration characterizing the Cauca River Valley to the east of Vijes, where pre-harvest sugar cane burning is common.
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