Lisbon air quality: evaluating traffic hot-spots

2009 ◽  
Vol 39 (3/4) ◽  
pp. 306 ◽  
Author(s):  
Abel Martins ◽  
Mario Cerqueira ◽  
Francisco Ferreira ◽  
Carlos Borrego ◽  
Jorge H. Amorim
Keyword(s):  
Air Quality ◽  
Hot Spots

Capturing Spatial and Temporal Patterns of NO2 in Cities using mobile and stationary DOAS measurements

2021 ◽  
Author(s):  
Mark Wenig ◽  
Sheng Ye ◽  
Ying Zhu ◽  
Hanlin Zhang
Keyword(s):  
Air Quality ◽  
Hot Spots ◽  
Temporal Patterns ◽  
Optical Absorption Spectroscopy ◽  
Spatial And Temporal Patterns ◽  
The Public ◽  
Measurement Height ◽  
Weekly Cycles

<p>The problem of elevated NO<sub>2</sub> levels in cities has gained some attention in the public in recent years and has given rise to questions about the plausibility of banning diesel engines in cities, the meaning of exceedances of air quality limits and the effects of corona lock-downs on air quality to name a few. Urban air quality is typically monitored using a relatively small number of monitoring stations. Those in-situ measurements follow certain guidelines in terms of inlet height and location relative to streets, but the question remains how a limited number of point measurements can capture the spatial variability in cities. In this talk we present two measurement campaigns in Hong Kong and Munich where we utilized a combination of mobile in-situ and stationary remote sensing differential optical absorption spectroscopy (DOAS) instruments. We developed an algorithm to separate spatial and temporal patterns in order to generate pollution maps that represent average NO<sub>2</sub> exposure. </p> <p>We use those maps to identify pollution hot spots and capture the weekly cycles of on-road NO2 levels and spatial dependency of long-term changes and we analyze how on-road measurements compare to monitoring station data and how the measurement height and distance to traffic emissions have to be considered when interpreting observed concentration patterns.</p>

Project Level Carbon Monoxide Hot-Spot Analysis for Level of Service D Intersections

1998 ◽  
Vol 1641 (1) ◽  
pp. 73-80 ◽  
Author(s):  
Yu Meng ◽  
Debbie A. Niemeier
Keyword(s):  
Carbon Monoxide ◽  
Air Quality ◽  
Hot Spots ◽  
Hot Spot ◽  
Quality Analysis ◽  
Level Of Service ◽  
Background Concentration ◽  
Hot Spot Analysis ◽  
Spot Analysis ◽  
Project Level

Hot-spot [localized carbon monoxide (CO) and particulate matter (PM10) violations] analysis is often required by the Environmental Protection Agency (EPA) to determine project level air quality conformity of transportation projects in accordance with state implementation plans. EPA uses intersection level of service (LOS) as one of its major criteria for identifying potential CO hot spots. EPA’s 1992 Guideline for Modeling CO from Roadway Intersections states that hot-spot analysis is not required for those intersections operating at LOS A, B, or C (i.e., these intersections are automatically eliminated as potential CO hot spots), whereas intersections operating at LOS D or worse must undergo detailed CO concentration analysis. Of all possible LOS D intersections, clearly only a few will actually require detailed modeling of CO concentrations. A new screening methodology that introduces the concept of meteorological situation-orientated reference charts is presented. Variations on the basic reference charts can incorporate such effects as signal type (e.g., pretimed versus actuated) and future fleet characteristics. Once the desired reference charts have been developed, to use them the analyst needs only to identify the applicable reference chart on the basis of the location of the project at hand and an approximate background concentration. The proposed screening methodology should save both effort and money often wasted on the redesign of intersections that are predicted to be hot spots at the time of air quality conformity analysis and when detailed air quality analysis of LOS D intersections is undertaken for intersections that are unlikely to be CO hot spots.

A high-performance oil-free backing pump for electron microscopes

1978 ◽  
Vol 36 (1) ◽  
pp. 110-111
Author(s):  
G.K.W. Balkau ◽  
E. Bez ◽  
J.L. Farrant
Keyword(s):  
Molecular Weight ◽  
Electron Microscope ◽  
Hot Spots ◽  
High Performance ◽  
Carbonaceous Material ◽  
Contamination Rate ◽  
Low Molecular Weight ◽  
Principal Source ◽  
Rotary Pumps ◽  
Electron Microscopes

The earliest account of the contamination of electron microscope specimens by the deposition of carbonaceous material during electron irradiation was published in 1947 by Watson who was then working in Canada. It was soon established that this carbonaceous material is formed from organic vapours, and it is now recognized that the principal source is the oil-sealed rotary pumps which provide the backing vacuum. It has been shown that the organic vapours consist of low molecular weight fragments of oil molecules which have been degraded at hot spots produced by friction between the vanes and the surfaces on which they slide. As satisfactory oil-free pumps are unavailable, it is standard electron microscope practice to reduce the partial pressure of organic vapours in the microscope in the vicinity of the specimen by using liquid-nitrogen cooled anti-contamination devices. Traps of this type are sufficient to reduce the contamination rate to about 0.1 Å per min, which is tolerable for many investigations.

Application of Electron Optics to Characterization of Particulate Pollutants

1972 ◽  
Vol 30 ◽  
pp. 364-365
Author(s):  
J. B. Moran ◽  
J. L. Miller
Keyword(s):  
Air Quality ◽  
Quality Standards ◽  
Ambient Air ◽  
Hazardous Substances ◽  
Fuel Additives ◽  
Ambient Air Quality ◽  
Air Quality Standards ◽  
Emission Standards ◽  
Stationary Sources ◽  
Ambient Air Quality Standards

The Clean Air Act Amendments of 1970 provide the basis for a dramatic change in Federal air quality programs. The Act establishes new standards for motor vehicles and requires EPA to establish national ambient air quality standards, standards of performance for new stationary sources of pollution, and standards for stationary sources emitting hazardous substances. Further, it establishes procedures which allow states to set emission standards for existing sources in order to achieve national ambient air quality standards. The Act also permits the Administrator of EPA to register fuels and fuel additives and to regulate the use of motor vehicle fuels or fuel additives which pose a hazard to public health or welfare.National air quality standards for particulate matter have been established. Asbestos, mercury, and beryllium have been designated as hazardous air pollutants for which Federal emission standards have been proposed.

Air Quality May Affect Infants' Brains

ASHA Leader ◽  
2013 ◽  
Vol 18 (2) ◽  
pp. 34-34
Keyword(s):  
Air Quality

Air Quality May Affect Infants' Brains

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