Distance from roads and cities as a predictor of habitat loss and fragmentation in the caatinga vegetation of Brazil.
(25/398)
Roads and cities represent huge sources of degradation for adjacent ecosystems regarding nutrient cycling, energy, water flow and species composition. In this study we test the hypothesis that distance from roads and cities is associated with habitat loss and fragmentation in the caatinga vegetation--a dry forest to scrub vegetation that covers ca. 736,000 km2 of northeast Brazil. The study site comprised a 2,828.8 km2 piece (64 km x 44.2 km) of Xingo region (09 degrees 36'S, 37 degrees 50'W), which is located between the States of Alagoas and Sergipe. Based on satellite imagery we mapped the remaining vegetation, 145 km of paved roads and the seven small-sized cities set in the study site. A positive correlation was found between the combined distance from roads and cities and the percentage of remaining vegetation as it dropped from 18% at 12 km distant to 5.9% at 1 km distant from cities and roads. Thus, remaining vegetation was reduced by one third near cities and roads. A positive correlation was also found between distance from cities and roads and the percentage of fragments larger than 200 ha, which ranged from 3.6% (within 3 km distance class) to 23.3% (15 km distance class) of all fragments. Our results suggest a road/city-effect zone of 12 to 15 km width, over which habitat loss and fragmentation extend throughout the caatinga vegetation. These findings should be considered in the regional polices for biodiversity conservation and economic development of the caatinga region. (+info)
Development and evaluation of a new push-pull ventilation system for sheet-adhesive work inside bus-body.
(26/398)
We present the performance of a new push-pull ventilation system for sheet-adhesive work inside the body of a sightseeing coach. The target sightseeing coach was 12 m long, 2.5 m wide and 2 m high from floor to ceiling. We made a prototype of an airflow system and a half-scale model of the bus-body. The half scale model was 6 m long, 1.25 m wide and 0.965 m high. The push-pull ventilation system and half-scale model were used to evaluate the flow distributions inside the model. We also measured the concentration of xylene and methanol vapors during simulated sheet-adhesive work. As a result, it was found that the best combination was a the push flow of 24 m3/min and a pull flow of 78 m3/min in this model, and the flow velocity in the model was less than 1 m/s. This system is potentially applicable to any interior work for not only bus-bodies but also train and airplane bodies, which have elongated and confined space with many openings. (+info)
Traffic density in California: socioeconomic and ethnic differences among potentially exposed children.
(27/398)
Motor vehicles are the main source of many hazardous air pollutants in California. Previous studies have shown that low-income and minority populations are more likely to live near industrial sources of pollution and in areas that do not meet national air quality standards. We estimated neighborhood exposures to motor vehicle emissions from a road network with daily traffic counts using a geographic information system. To calculate traffic density, we summed the average daily vehicle miles of travel per square mile of land area for each census block group in the state. We used 1990 census data to characterize the population by age, race and socioeconomic status in block groups with high traffic density. Block groups with more than 500,000 vehicle miles of travel per square mile were defined to be high traffic density. Statewide, about 5% of all block groups met this criterion and more than 215,000 children under 15 years of age lived in these high traffic density areas. Block groups in the lowest quartile of median family income were three times more likely to have high traffic density than block groups in the highest income quartile. The percentage of children living in high traffic density block groups increased with decreasing median family income for all race and ethnicities except White. Overall, children of color were about three times more likely to live in high-traffic areas than were white children. Based on this analysis, low-income and children of color have higher potential exposure to vehicle emissions. Future exposure assessment studies should target the highest traffic density areas, and health studies should consider the differences by income and race or ethnicity during design. (+info)
The effect of an overpass on pedestrian injuries on a major highway in Kampala - Uganda.
(28/398)
OBJECTIVES: To describe the pedestrian population, their use of an overpass, and to assess pedestrian perceptions and responses to the risk of traffic crashes, determine pedestrian injuries in relation to traffic flow, and compare traffic crash and pedestrian injury rates before and after the overpass construction. SETTING: The study was conducted in Nakawa trading center approximately six kilometers from the center of Kampala city on a major highway. The trading center has a busy market, small retail shops, industries, a sports stadium, offices, low cost housing estates, schools, and an estimated population of 6,226 residents, 15.1% of them students. METHODOLOGY: Pedestrian road behavior and traffic patterns were observed, and police traffic crash records reviewed, one year before and one year after overpass construction. A convenient sample of overpass and non-overpass users was interviewed to assess their perceptions of risk. RESULTS: A total of 13,064 pedestrians were observed (male: female ratio= 2.2:1). The overall prevalence of pedestrian overpass use was 35.4%. A bigger proportion of females (49.1%) crossed on the overpass compared to males (29.2%). More children (79.7%) than adults (27.3%) used the overpass. The majority of pedestrians (77.9%) were worried about their safety in traffic but only 6.6% thought of the overpass as an appropriate means to avoid traffic accidents. Traffic was not segregated by vehicle type. Mean traffic flow varied from 41.5 vehicles per minute between 0730-0830 hours, to 39.3 vehicles per minute between 1030-1130 hours and 37.7 vehicles per minute between 1730-1830 hours. The proportion of heavy vehicles (lorries, trailers, tankers, and tractors) increased from 3.3% of total vehicle volume in the morning to 5.4% in the evening (t = 2.847, p <0.05); 44.0% of the collisions occurred in the evening with 35 pedestrian casualties before and 70 after the overpass intervention. CONCLUSIONS: The prevalence of pedestrian overpass use was low with adult males least likely to use it. Pedestrians had a high perception of risk, which did not seem to influence overpass use. Pedestrian were more likely to be injured during slow traffic flows. There were more traffic crashes, and pedestrian injuries, but fewer fatalities after the construction of the overpass. (+info)
Urban traffic and pollutant exposure related to respiratory outcomes and atopy in a large sample of children.
(29/398)
Conflicting results have been reported for the relationship between traffic exposure and inception of atopy. The effect of traffic on the prevalence of asthma and atopy at school age was investigated in a representative population. Random samples of schoolchildren (n=7,509, response rate 83.7%) were studied using the International Study of Asthma and Allergies in Childhood phase-II protocol with skin-prick tests, measurements of specific immunoglobulin E and lung function. Traffic exposure was assessed via traffic counts and by an emission model which predicted soot, benzene and nitrogen dioxide (NO2). Traffic counts were associated with current asthma, wheeze and cough. In children with tobacco-smoke exposure, traffic volume was additionally associated with a positive skin-prick test. Cough was associated with soot, benzene and NO2, current asthma with soot and benzene, and current wheeze with benzene and NO2. No pollutant was associated with allergic sensitisation. High vehicle traffic was associated with asthma, cough and wheeze, and in children additionally exposed to environmental tobacco smoke, with allergic sensitisation. However, effects of socioeconomic factors associated with living close to busy roads cannot be ruled out. (+info)
Climate, traffic-related air pollutants and allergic rhinitis prevalence in middle-school children in Taiwan.
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The prevalence of allergic rhinitis, a common respiratory disorder, may be rapidly increasing. Epidemiological studies, however, indicate little about its association with climatic factors and air pollution. The relationship between traffic-related air pollutants and allergic rhinitis in middle-school students was therefore investigated. In a nationwide survey of middle-school students in Taiwan conducted in 1995/1996, the lifetime prevalence of physician-diagnosed allergic rhinitis and typical symptoms of allergic rhinitis were compared with air-monitoring station data on temperature, relative humidity, sulphur dioxide (SO2), nitrogen oxides (NOx), ozone (O3), carbon monoxide (CO) and particulate matter with a 50% cut-off aerodynamic diameter of 10 microm (PM10). A total of 331,686 nonsmoking children attended schools located within 2 km of 55 stations. Mean (range) annual exposures were: CO 853 (381-1,610) parts per billion (ppb), NOx 35.1 (10.2-72.4) ppb, SO2 7.57 (0.88-21.2) ppb, PM10 69.2 (40.1-116.2) microg x m(-3), O3 21.3 (12.4-34.1) ppb, temperature 22.9 (19.6-25.1) degrees C, and relative humidity 76.2 (64.8-86.2)%. The prevalence of physician-diagnosed allergic rhinitis was 28.6 and 19.5% in males and females, respectively, with prevalence of questionnaire-determined allergic rhinitis 42.4 and 34.0%. After adjustment for age, parental education and history of atopic eczema, physician-diagnosed allergic rhinitis was found to be associated with higher nonsummer (September-May) warmth and traffic-related air pollutants, including CO, NOx and O3. Questionnaire-determined allergic rhinitis correlated only with traffic-related air pollutants. Nonsummer warmth and traffic-related air pollution, probably mediated through exposure to common allergens such as dust mites, are possible risk factors for allergic rhinitis in middle-school-aged children. (+info)
Lung cancer in heavy equipment operators and truck drivers with diesel exhaust exposure in the construction industry.
(31/398)
BACKGROUND: Several studies indicate that truck drivers have an increased risk of lung cancer, but few studies have examined lung cancer risk in heavy equipment operators. Workers in both occupations are exposed to diesel exhaust. AIMS: To examine the incidence and mortality from lung cancer among truck drivers and among drivers of heavy vehicles. METHODS: A computerised register of Swedish construction workers participating in health examinations between 1971 and 1992 was used. Male truck drivers (n = 6364) and drivers of heavy construction vehicles (n = 14 364) were selected as index groups; carpenters/electricians constituted the reference group (n = 119 984). RESULTS: Operators of heavy construction equipment experienced no increased risk of lung cancer compared to risk among the carpenter/electrician referents (61 cases v 70.1 expected). However, a significant inverse trend risk with increasing use of cabins was apparent. Truck drivers had increased risks of cancer of the lung (61 cases v 47.3 expected) and prostate (124 cases v 99.7 expected), although only mortality for lung cancer was significantly increased. Comparisons with the general population showed similar results. CONCLUSION: Results are consistent with those of previous studies suggesting that heavy equipment operators with potential exposure to diesel exhaust may have little or no increased risk of lung cancer, although the use of cabins seemed to decrease the risk of lung cancer. The results for truck drivers are also consistent with previous reports of increased lung cancer risk among truck drivers exposed to diesel exhaust, as well as recent reports linking diesel exhaust exposure to prostate cancer. (+info)
The effect of seat design on vibration comfort.
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A field study was done to evaluate different seat designs in the aspect of minimizing vibration transmission and reducing the level of discomfort experienced by drivers subjected to transient vibration. Two seat designs (sliding or fixed in the horizontal direction) were compared in an experiment based on variation of sitting posture, speed, and type of obstacle. The comparison was done by assessing discomfort and perceived motion and by vibration measurement. Ten professional drivers were used as participants. Maximum Transient Vibration Value and Vibration Dose Value were used in the evaluation. The results showed that a sliding seat is superior in attenuating vibration containing transient vibration in the horizontal direction. It was also perceived as giving less overall and low back discomfort compared to a fixed seat. (+info)