Periods Of High Pollution Research Articles

La pollution automobile à Paris influence du trafic et des conditions météorologiques

The improvement of urban air quality is a major challenge namely for NO2 (nitrogen dioxide), a toxic pollutant controlled by the European Regulation EEC no85–203. We now know that eatalytic converters reduce car emissions and we believe that a reduction in traffic (already enforced in some cities) and the restriction of vehicle road traffic, applied to some European towns, is an area for further research. In Paris, the existance of periods of serious pollution (essentially due to NO2 levels reaching >200 μg/m3 in periods of several hours) has made the public and public administration aware of the importance of this problem. Thus, a commitment has been made to reduce these periods of severe pollution. The study being presented deals with the search for a correlation between vehicle traffic (vehicle flow/hour) and measured concentrations of NO, NO2 and CO at two sites in Paris, in 1992. This relation has been established by plotting the traffic levels against concentrations of each gaseous effluent. When the pollutants are well dispersed it is possible to plot the concentrations of NO and NO2. The slope is much steeper for NO than for NO2. On the other hand, when meterological conditions are unfavourable (high pressure zone, stability of the atmosphere, temperature inversion or strong solar radiance) no significant correlation could be observed. This proves the predominance of meteorological conditions on NO2 levels during high pollution periods. The study also confirmed that NO is a very good indicator of car pollution, taking into account the increasing number of diesel powered vehicles in France.

Synoptic Classification and Physical Model Experiments to Guide Field Studies in Complex Terrain

Abstract Synoptic classification is used to identify meteorological conditions characteristic of high-pollution periods at Nogales, Arizona. Low surface winds determined by local surface cooling at night with little vertical mixing were found to be most important. This condition was simulated in a 0.79-m-square box filled with water with the lower surface made to model a 12-km-square region of the surface topography of the United States-Mexico border at Nogales. The aluminum base was cooled to induce the downslope flows. Photographs of dye initially placed on the surface at many locations were used to obtain a set of surface velocities that formed the input to the Diagnostic Wind Model (DWM). The DWM provided hourly velocity data with grids of 500- and 250-m spacings. The similarity arguments used to analyze the relationship of the physical model to the atmosphere are discussed. Although the magnitude of the wind vectors in the physical model cannot be matched to the atmosphere, the directions can be used...

Exacerbations of Childhood Asthma and Ozone Pollution in Atlanta

Asthma prevalence and mortality due to asthma have been increasing during the last decade, and both the rates and the increases in rates have been higher for blacks than whites and higher for children than adults. Whether environmental factors such as air pollution contribute to these increases is unknown. The purpose of this study was to examine the relationship between emergency visits to a hospital for childhood asthma and exposure to ozone in an indigent, predominantly black population. Data were collected by abstracting clinical records for all children with asthma or reactive airway disease in one public hospital during the summer of 1990. From June 1, 1990, to August 31, 1990, 609 visits were made by children aged 1 to 16 years to an emergency clinic for treatment of asthma or reactive airway disease. Monitoring data indicated that maximum ozone levels equalled or exceeded 0.11 ppm on 6 days during the study period. The average number of visits for asthma or reactive airway disease was 37% higher on the days after those 6 days (from 6:00 PM to 6:00 PM the next day) than on other days (95% CI, RR = 1.02-1.73). The results of the study suggest that among black children from low-income families, asthma may be exacerbated following periods of high ozone pollution.

Diurnal and seasonal modelling of the tropospheric half-lives of polycyclic aromatic hydrocarbons

The half-lives of polycyclic aromatic hydrocarbons (PAH) were calculated under different conditions of location, season, and time of day, based on the reaction of PAH with the hydroxyl radical OH as the major sink. The calculations required a method of estimating the diurnal variation in the concentration of OH, which is not normally available experimentally. For naphthalene as a prototype PAH, the half-lives were of the order of several hours, but varied by more than an order of magnitude with season and geographical location. The previously developed model applicable to rural atmospheres was modified to estimate the half-lives of PAH in the urban troposphere by including of the reaction of OH with NO2 as a major urban sink for OH. The half-lives of several PAH were estimated for North York, Ontario, under different conditions of NO2 and ozone concentrations during a period of high tropospheric air pollution in July 1988.

Frequency of potential contributions by major sources to ground level concentrations of so 2 in the forth valley, scotland: an application of acoustic sounding

Inversion statistics based on acoustic sounding or SODAR returns for a 12-month period during 1976–1977 were used in the estimation of the frequencies of potential contribution to ground-level SO 2 concentrations by major sources in the Forth Valley, Scotland. The sources were categorized by stack height and assumptions made regarding both effective emission heights and abilities to penetrate elevated and ground-based inversions. The results are presented for the whole summer and winter 6-month periods and for a selection of high-pollution periods during each of these seasons. Comparison between distributions of source contributions and SODAR categories by hour of day gives an indication of the potentially more significant times of contribution during the 24-h period.

The Livermore Regional Air Quality Model: II. Verification and Sample Application in the San Francisco Bay Area

Abstract Topographic, meteorological, source emission and atmospheric pollutant concentration data have been assembled for use in verifying the LIRAQ-1 and LIRAQ-2 regional air quality models in the San Francisco Bay Area. These data, collected primarily during the high-pollution period of 26–27 July 1973, indicate that the temporal and spatial phasing for concentrations of carbon monoxide, ozone and nitrogen oxides can be adequately represented by the models. Sensitivity studies indicate that initial and horizontal boundary conditions as well as grid size and subgrid-scale effects, while very significant in predicting air quality on the local scale, are less important in dealing with regional concentrations of pollutants than are emissions, meteorological conditions and vertical boundary conditions.

Day-to-day changes in ventilatory function in relation to the environment: Part I. Spirometric values

Measurements of forced expiratory volume at 1 second, forced vital capacity, and maximum midexpiratory flow have been made on four normal subjects employed in central London on each working day for five years. For three of the subjects, MMF was highest on days with low concentrations of smoke and sulphur dioxide, and it decreased at successively higher concentrations, but it was not clear whether this was an effect of pollution or of other associated factors. Respiratory infections were found to have pronounced effects on these spirometric measurements, and analysis of the results for the complete series revealed small seasonal variations and long-term changes, some of which were large and in the opposite direction from those expected with increasing age. Some immediate but transient effects of pollution on the spirometric values were seen following exercise in periods of high pollution. In addition to small direct effects, the role of pollution in affecting the course of respiratory infections and thus indirectly further affecting ventilatory function was considered.

An Air Pollution Incident Due to a Stationary Front

In January 1971, the New York City area experienced a period of high pollution in which concentrations exceeded the present criteria for Stage I of the New York City Alert-Warning System. The incident was unusual because the high concentrations were associated with a weak frontal system which moved back and forth over the area and not with a stagnating anticyclone. Concentrations of pollutants were found to be closely related to the movement of the frontal system as well as to changes in wind speed and stability. Climatological criteria for identifying-periods of potential high air pollution and the criteria for mixing heights, transport wind speed and ventilation factors necessary for the issuance of an official advisory from the National Meteorological Center were not met during this incident. Therefore, some re-evaluation and redefinition of these criteria are recommended.

Health effects of air pollution.

Air pollution can be a minor health problem or a threat to life. The physician should be prepared to counsel susceptible patients on avoiding and reducing risks and to give them special attention during periods of high pollution.

Measurements of morbidity and mortality related to air pollution.

Examination of total deaths in New York City by day of occurrence shows periodic peaks in mortality which are associated with periods of high air pollution. These peaks are usually associated with periods of low wind speed and temperature inversion conditions which permit air pollution to build up to high levels. Unlike the experience of London, fog is not a necessary part of this picture, and therefore the presence of these episodes is often not apparent at the time to most inhabitants. A characteristic feature of these episodes is the immediate rise in mortality occurring on the same day as the peaks of pollution. A second characteristic is their frequent influence on death rates in the 45–64 year age group as well as in those over 65. These characteristics suggest that if these excess deaths are related to air pollution (as we believe to be highly likely) the mechanism is probably protean and pervasive affecting the course of a variety of different diseases through a basic physiologic effect. The relat...

Excess mortality as an indicator of health effects of air pollution.

Examination of total deaths in New York City by day of occurrence shows periodic peaks in mortality which are associated with periods of high air pollution. These peaks are usually associated with periods of low wind speed and temperature inversion conditions which permit air pollution to build up to high levels. Unlike the experience of London, fog is not a necessary part of this picture, and therefore the presence of these episodes is often not apparent at the time to most inhabitants. A characteristic feature of these episodes is the immediate rise in mortality occurring on the same day as the peaks of pollution. A second characteristic is their frequent influence on death rates in the 45- to 64-year age group as well as in those over 65. These characteristics suggest that if these excess deaths are related to air pollution, the mechanism is probably protean and pervasive, affecting the course of a variety of different diseases through a basic physiologic effect. 5 figures.

A calibration of the filter-paper method of estimation of smoke

During a period of high pollution in December 1962 smoke samples were taken on Whatman cellulose fibre paper and on glass fibre paper, and the weight collected on the latter was used to derive a calibration curve for the standard filter-paper method of estimation of smoke. While the samples from which the calibration was derived were being collected the nature of the pollution changed very little, but qualitative changes in pollution may result from altered weather conditions and the errors which this introduces are considered. The effects which the texture of the paper and the colour and overlapping of the particles may have on the measured reflectance are also discussed.

Air Pollution Potential East of the Rocky Mountains: Fall 1959

The weather over the eastern two-thirds of the United States was monitored, and air pollution potential forecasts were made and disseminated to affected cities. The experiment allowed for air sampling under a variety of synoptic patterns, and the results strengthen the validity of the previously developed criteria as indicators of prolonged periods of two or more days of high air pollution. Other considerations are indicated for the prediction of isolated days (not prolonged periods) of high pollution.