Cardiovascular health and particulate vehicular emissions: a critical evaluation of the evidence

A major public health goal is to determine linkages between specific pollution sources and adverse health outcomes. This paper provides an integrative evaluation of the database examining effects of vehicular emissions, such as black carbon (BC), carbonaceous gasses, and ultrafine PM, on cardiovascular (CV) morbidity and mortality. Less than a decade ago, few epidemiological studies had examined effects of traffic emissions specifically on these health endpoints. In 2002, the first of many studies emerged finding significantly higher risks of CV morbidity and mortality for people living in close proximity to major roadways, vs. those living further away. Abundant epidemiological studies now link exposure to vehicular emissions, characterized in many different ways, with CV health endpoints such as cardiopulmonary and ischemic heart disease and circulatory-disease-associated mortality; incidence of coronary artery disease; acute myocardial infarction; survival after heart failure; emergency CV hospital admissions; and markers of atherosclerosis. We identify numerous in vitro, in vivo, and human panel studies elucidating mechanisms which could explain many of these cardiovascular morbidity and mortality associations. These include: oxidative stress, inflammation, lipoperoxidation and atherosclerosis, change in heart rate variability (HRV), arrhythmias, ST-segment depression, and changes in vascular function (such as brachial arterial caliber and blood pressure). Panel studies with accurate exposure information, examining effects of ambient components of vehicular emissions on susceptible human subjects, appear to confirm these mechanisms. Together, this body of evidence supports biological mechanisms which can explain the various CV epidemiological findings. Based upon these studies, the research base suggests that vehicular emissions are a major environmental cause of cardiovascular mortality and morbidity in the United States. As a means to reduce the public health consequences of such emissions, it may be desirable to promulgate a black carbon (BC) PM2.5 standard under the National Ambient Air Quality Standards, which would apply to both on and off-road diesels. Two specific critical research needs are identified. One is to continue research on health effects of vehicular emissions, gaseous as well as particulate. The second is to utilize identical or nearly identical research designs in studies using accurate exposure metrics to determine whether other major PM pollutant sources and types may also underlie the specific health effects found in this evaluation for vehicular emissions

The effect of giving verbal reasons during or after the solution of practice problems on transfer performance.

The effect of giving verbal reasons during or after the solution of practice problems on transfer performance

Trend Reversal in Lake Michigan Contribution to Snowfall

AbstractOne of the most notable ways the Laurentian Great Lakes impact the region’s climate is by augmenting snowfall in downwind locations during autumn and winter months. Among many negative consequences, this surplus of snow can cause substantial property damage to homes and can escalate the number of traffic accident–related injuries and fatalities. The consensus among several previous studies is that lake-effect snowfall increased during the twentieth century in various locations in the Great Lakes region. The goal of this study is to better understand variability and long-term trends in Lake Michigan’s lake-contribution snowfall (LCS). LCS accounts for both lake-effect and lake-enhanced events. In addition, this study updates findings from previous investigations using snowfall observations found by a recent study to be appropriate for climate studies. It is demonstrated that considerable variability exists in 5-yr periods of LCS east and south of Lake Michigan from 1920 to 2005. A general increase in LCS from the early 1920s to the 1950–80 period at locations typically downwind of the lake was found. Thereafter, LCS decreased through the early 2000s, indicating a distinct trend reversal that is not reported by earlier studies. The reasons for this reversal are unclear. The reversal is consistent with observed increasing minimum temperatures during winter months after the 1970s, however.</jats:p

A Climatology and Case Study of Continental Cold Season Dense Fog Associated with Low Clouds

Abstract This study focuses on dense fog cases that develop in association with low clouds and sometimes precipitation. A climatology of weather conditions associated with dense fog at Peoria, Illinois, for October–March 1970–94 indicated that fog forming in the presence of low clouds is common, in 57% of all events. For events associated with low pressure systems, low clouds precede dense fog in 84% of cases. Therefore, continental fogs often do not form under the clear-sky conditions that have received the most attention in the literature. Surface cooling is usually observed prior to fog on clear nights. With low cloud bases, warming or no change in temperature is frequent. Thus, fog often forms under conditions that are not well understood, increasing the difficulty of forecasting fog. The possible mechanisms for fog development under low cloud-base conditions were explored for an event when dense fog covered much of Illinois on 7 November 2006. Weather Surveillance Radar-1988 Doppler (WSR-88D) and rawinsonde observations indicated that evaporating precipitation aloft was important in moistening the lower atmosphere. Dense fog occurred about 6 h following light precipitation at the surface. The surface was nearly saturated following precipitation, but relative cooling was needed to overcome weak warm air advection and supersaturate the lower atmosphere. Surface (2 m) temperatures were near or slightly cooler than ground temperatures in most of the region, suggesting surface sensible heat fluxes were not important in this relative cooling. Sounding data indicated drying of the atmosphere above 800 hPa. Infrared satellite imagery indicated deep clouds associated with a low pressure system moved east of Illinois by early morning, leaving only low clouds. It is hypothesized that radiational cooling of the low cloud layer was instrumental in promoting the early morning dense fog.</jats:p

Observations of the Cross-Lake Cloud and Snow Evolution in a Lake-Effect Snow Event

AbstractWhile the total snowfall produced in lake-effect storms can be considerable, little is known about how clouds and snow evolve within lake-effect boundary layers. Data collected over Lake Michigan on 10 January 1998 during the Lake-Induced Convection Experiment (Lake-ICE) are analyzed to better understand and quantify the evolution of clouds and snow. On this date, relatively cold air flowed from west to east across Lake Michigan, creating a quasi-steady-state boundary layer that increased from ≈675 to ≈910 m in depth over a distance of 80 km. Once a cloud deck formed 14–18 km from the upwind shoreline, maximum cloud particle concentrations and liquid water content increased from west to east across the lake. Correspondingly, maximum ice water contents, snowfall rates, and maximum snow particle diameters also increased across the lake. Maximum particle concentrations were found below the mean top of the boundary layer and above the cloud base for both cloud and snow particles.Surprisingly, snow particles were observed 3–7 km upwind of the upwind edge of the lake-effect cloud deck. These snow particles were observed to be rather spatially uniform throughout the boundary layer. Based on available observations, it is hypothesized that of the mechanisms that could produce this snow, the majority of it originated from transient clouds located near the upwind shore. In addition, maximum snow particle concentrations peaked near the middle of the lake before decreasing toward the downwind shore, indicating the location after which aggregation became an important snow growth mechanism. These results show that the evolution of clouds and snow within lake-effect boundary layers may not occur in the uniform manner often depicted in conceptual models.</jats:p

Blowing Snow as a Natural Glaciogenic Cloud Seeding Mechanism

Abstract Winter storms are often accompanied by strong winds, especially over complex terrain. Under such conditions freshly fallen snow can be readily suspended. Most of that snow will be redistributed across the landscape (e.g., behind obstacles), but some may be lofted into the turbulent boundary layer, and even into the free atmosphere in areas of boundary layer separation near terrain crests, or in hydraulic jumps. Blowing snow ice crystals, mostly small fractured particles, thus may enhance snow growth in clouds. This may explain why shallow orographic clouds, with cloud-top temperatures too high for significant ice initiation, may produce (usually light) snowfall with remarkable persistence. While drifting snow has been studied extensively, the impact of blowing snow on precipitation on snowfall itself has not. Airborne radar and lidar data are presented to demonstrate the presence of blowing snow, boundary layer separation, and the glaciation of shallow supercooled orographic clouds. Further evidence for the presence of blowing snow comes from a comparison between snow size distributions measured at Storm Peak Laboratory (SPL) on Mount Werner (Colorado) versus those measured aboard an aircraft while passing overhead, and from an examination of snow size distributions at SPL under diverse weather conditions. Ice splintering following the collision of supercooled droplets on rimed surfaces such as trees does not appear to explain the large concentrations of small ice crystals sometimes observed at SPL.</jats:p

The Unusual Weather in 2009 in Illinois Created Major Economic Impacts

Abnormal weather conditions existed in Illinois during every month from March 2009 through November 2009. March–August conditions were exceptionally wet and cool with frequent cloudy skies. The fall months brought a dry September, a cold and wet October, and a warm and dry November. Wet, cool spring conditions delayed planting of major crops and led to flooding along many rivers. Summer temperatures were nearly 3 degrees F below normal, reducing the use of air conditioning but delaying crop maturity. Summer 2009 was rated as the 8th wettest and 11th coldest in Illinois since 1895. A shift to warm and dry weather in September, followed by cool and wet conditions in October sustained flooding and delayed harvesting of Illinois crops. Conditions shifted again in November, becoming warm and relatively dry, so corn and soybean harvesting moved forward rapidly. In early December, most soybeans had been harvested, but 15 percent of the corn crop was still in the fields. The crop harvest in 2009 was rated as the slowest ever in Illinois. The unusual weather during the 2009 crop season led to worries over production, yet near-record-high yields were recorded for corn (174 bu/acre) and soybeans (46 bu/acre). These large yields helped farm incomes, but delays in corn drying and tillage (preparing soil for future planting) increased costs. In addition, high yields across the Corn Belt lowered crop prices, which also decreased farm incomes. Storms in 2009 were more frequent than usual and resulted in extensive property damage in Illinois. Included were four record-setting rainstorms and several hailstorms. Storms in northern Illinois produced large hailstones of 2 inches in diameter, frequent cases of high winds with gusts greater than 60 mph, and 18 tornadoes. More than 400 million dollars in property losses were reported along with 120 million dollars in crop losses from severe storms. Flooding on most rivers occurred various times during March–November 2009. The Illinois River was above flood stage for 89 consecutive days, setting a new record. Heavy rains of 2009 helped bring Lake Michigan’s level up to near average for the first time since 2004. Wet and cloudy conditions affected human behavior, including a reduction in retail shopping. Construction and repair of highways and buildings were delayed, a negative outcome in a struggling economic time across the nation. The unusual weather in 2009 persisted through December, and some of the 2009 weather impacts continued into the following months of 2010. Corn harvesting in northern Illinois continued into January 2010, soil tillage awaited drier conditions in the spring of 2010, and fertilizer applications in the fall of 2009 were delayed until 2010. Flooding on the Illinois River and several of its tributaries also continued into January 2010.published or submitted for publicationis peer reviewe

2004: Comparison of observations with idealized model results for a method to resolve winter lake-effect mesoscale morphology

ABSTRACT Forecasters in the Great Lakes region have for several decades recognized a general relationship of wind speed and overlake fetch to lake-effect snowstorm morphology. A recent study using idealized mesoscale model simulations of lake-effect conditions over circular and elliptical lakes showed the ratio of wind speed to maximum fetch distance (U/L) may be used to effectively predict lake-effect snowstorm morphology. The current investigation provides an assessment of the U/L criteria using observational datasets. Previously published Great Lakes lake-effect snowstorm observational studies were used to identify events of known mesoscale morphology. Hindcasts of nearly 640 lake-effect events were performed using historical observations with U/L as the predictor. Results show that the quantity U/L contains important information on the different mesoscale lake-effect morphologies; however, it provides only a limited benefit when being used to predict mesoscale morphology in real lake-effect situations. The U/L criteria exhibited the greatest probability of detecting lake-effect shoreline band events, often the most intense, but also experienced a relatively large number of false hindcasts. For Lakes Erie and Ontario the false hindcasts and biases were reduced and shoreline band events that occurred under higher wind speed conditions were better identified. In addition, the Great Lakes Environmental Research Laboratory ice cover digital dataset was used in combination with observations from past events to assess the impact of ice cover on the use of U/L as a predictor of lake-effect morphology. Results show that hindcasts using the U/L criteria were slightly improved when the reduction of open-water areas due to lake ice cover was taken into account