Clean Air Areas Research Articles

Response of Common Garden Plant Leaf Traits to Air Pollution in Urban Parks of Suzhou City (China)

In this study, to comprehensively investigate the impact of garden plants on air quality, we measured the leaves of 18 common garden plants in three different areas, namely, Suzhou industrial parks (clean air area (CAA)), Xiangcheng district parks (lightly polluted area (LPA)), and Huqiu district parks (highly polluted area (HPA)). We also measured the leaf functional traits of different life-types of plants. To explore the trade-off strategies of the leaf traits of common garden plants in response to air pollution and to assess the adaptive capacity of different life types of plants to air pollution. The results show that plants in the polluted area had higher leaf dry matter content (LDMC) and leaf nitrogen content per unit mass (Nmass), and a lower specific leaf area (SLA), maximum net photosynthetic rate per unit area (Aarea), transpiration rate (Tr), stomatal conductance (Gs), and chlorophyll value (SPAD). Pearson correlation analysis showed that SLA was significantly positively correlated with Nmass, Tr, photosynthetic use efficiency (PNUE), and SPAD, and significantly negatively correlated with LDMC, while Aarea was significantly positively correlated with chlorophyll value. Redundancy analysis revealed that the correlation between each leaf functional trait and atmospheric pollution factors was as follows: LDMC > Nmass > SLA > LA > Aarea > Tr > PNUE > SPAD. The results suggest that different plant types have varying levels of adaptability to environmental conditions. Trees were found to be the most adaptable, followed by shrubs, herbs, and lianas. Additionally, under the stress of air pollution, herbs and lianas exhibited characteristics of “fast investment-return” on the leaf economic spectrum, meaning they were able to quickly allocate resources to maximize their return. However, trees and shrubs displayed traits of “slow investment-return”, indicating a more conservative approach to resource allocation. These results provide valuable insights into the leaf trade-off strategies of plants in Suzhou Park under air pollution stress and can guide the selection of suitable plant species in similar environments.

Study on the transmission route of virus aerosol particles and control technology of air conditioning in the enclosed space.

The patient’s breathing and air conditioning system in the enclosed space are the main factors that cause indoor cross-infection. However, the research on the influence and the control mechanism of different air conditioning systems on the transmission path of virus aerosol particles exhaled by patients is still limited. To evaluate the effects of different air conditioning systems on the spread of human exhaled pollutants, computational fluid dynamics (CFD) was used to study the movement and diffusion of exhaled air from two rows of 12 sitting adults in a hospital's closed transfusion room. In this paper, three different air conditioning systems are considered: Ceil-supply and Down-return (Ceil-to-Down), Up-supply and Down-return (Up-to-Down), Down-supply and Up-return (Down-to-Up). The distribution of exhaled air velocity, temperature, and virus particle concentration were studied, and it is found that the horizontal diffusion distance of exhaled pollutants is about 0.75 –1.1 m. When up to down systems are used, the air conditioning system shall be closed in time in case of respiratory infectious diseases, so as to avoid cross-infection in the enclosed space. A relatively clean air area with a height of about 1.1 m will be formed, which can inhibit the transmission of the virus to a certain extent when using the down-to-up system. But for those who are exposed to the enclosed space for a long time, the down-to-up system is not the most suitable air conditioning system.

Variation of radiative forcings and global warming potentials from regional aviation NOx emissions

The response to hemispherical and regional aircraft NOx emissions is explored by using two climate metrics: radiative forcing (RF) and Global Warming Potential (GWP). The global chemistry transport model, MOZART-3 CTM, is applied in this study for a series of incremental aircraft NOx emission integrations to different regions. It was found that the sensitivity of chemical responses per unit emission rate from regional aircraft NOx emissions varies with size of aircraft NOx emission rate and that climate metric values decrease with increasing aircraft NOx emission rates, except for Southeast Asia. Previous work has recognized that aircraft NOx GWPs may vary regionally. However, the way in which these regional GWPs are calculated are critical. Previous studies have added a fixed amount of NOx to different regions. This approach can heavily bias the results of a regional GWP because of the well-established sensitivity of O3 production to background NOx whereby the Ozone Production Efficiency (OPE) is greater at small background NOx. Thus, even a small addition of NOx in a clean-air area can produce a large O3 response. Using this ‘fixed addition’ method of 0.035 Tg(N) yr−1, results in the greatest effect observed for North Atlantic and Brazil, ∼10.0 mW m−2/Tg(N) yr−1. An alternative ‘proportional approach’ is also taken that preserves the subtle balance of local NOx–O3–CH4 systems with the existing emission patterns of aircraft and background NOx, whereby a proportional amount of aircraft NOx, 5% (N) yr−1, is added to each region in order to determine the response. This results in the greatest effect observed for North Pacific that with its net NOx RF of 23.7 mW m−2/Tg(N) yr−1 is in contrast with the ‘fixed addition’ method. For determining regional NOx GWPs, it is argued that the ‘proportional’ approach gives more representative results. However, a constraint of both approaches is that the regional GWP determined is dependent on the relative global emission pattern, so if that changes in the future, the regional NOx GWP will change.

The Prevalence of Respiratory Symptoms and Pulmonary Functions in Inhabitants Living at Clean Air Areas in Yamagata Prefecture

The Prevalence of Respiratory Symptoms and Pulmonary Functions in Inhabitants Living at Clean Air Areas in Yamagata Prefecture

Oxidative stress on plasmid DNA induced by inhalable particles in the urban atmosphere

Plasmid DNA assay is a newly-developedin vitro method to investigate bioreactivity of particles. In this paper, this method was used to study the bioreactivity of PM10 (particulate matter with aerodynamic diameter of less than 10 μm) and PM2.5 (particulate matter with aerodynamic diameter of less than 2.5 μm). Samples and dust storm particles were collected in 2001 in an urban area, a satellite city and a clean air area in Beijing. A big difference was found for oxidative DNA stress induced by different particulate matter (PM) samples, with the TM50 (particle mass causing 50% damage to DNA) values varying by a factor over 10. This was closely dependent on the sizes of particles as well as the variation in relative proportion of mineral matter. PM2.5 samples generally impose larger oxidative stress on plasmid DNA than PM10 samples. Airborne particles collected during dust storm episodes, usually with a higher proportion of mineral matter, have a much lower oxidative capacity than those collected during non-dust storm episodes. PM samples and their water-soluble fractions usually have similar bioreactivities, demonstrating that oxidative capacity of Beijing airborne particles is mainly sourced from their water-soluble fractions.

Characterization of airborne individual particles collected in an urban area, a satellite city and a clean air area in Beijing, 2001

Collection campaigns for PM10 and PM2.5 have been conducted in a northwestern Beijing urban area in monthly periods over 2001, with 7 days collection per month. The samples were also collected simultaneously in a satellite city, Nankou, and a clean air area near the Ming Tombs Reservoir (MTR) over the domestic heating (March) and non-heating (July/August) periods in 2001 (both for one week). To assist the analysis, three types of ‘source’ particulate matter (PM) samples were taken. These consisted of coal combustion ash collected on top of a coke oven; dust storm particles collected during dust storm periods; and roadside PM10 collected on a major road in Beijing. Monitoring results reveal that, in the urban area, particle mass levels were higher in winter than in other seasons. The 1-week/month average PM10 mass levels were over 250 ?gm?3 in winter. The particle mass levels in the satellite city were slightly lower than those at the urban site, and the lowest mass levels occurred at the MTR site. The morphology and chemical composition of individual airborne particles were determined by scanning electron microscopy, and image analysis was employed to study the number-size distributions. The number-size distributions of mineral particles showed that those in the Asia-Dust storm (ADS) collections are mostly coarser than 1 ?m, while mineral particles of the non-ADS collections are predominately finer than 1 ?m. The particles in the respirable (<2.5 ?m) fraction accounted for 99% of the total particles in airborne PM samples. Soot aggregates were generally the most abundant components in airborne PM samples at all three sites. The fly ash (spherical) particles at the MTR site were significantly enriched over the heating period, indicating a domestic coal-burning source.

Analyses of NOx and wet depositions at Mühleggerkböpfl, North Tyrolean Limestone Alps.

The intensive investigation site 'Mühleggerkopfl' in the North Tyrolean Limestone Alps can be classified as a clean-air area site. The mean concentrations of NOx are far below the effect-related limit value of the WHO (30 microg NOx m(-3)). The gravitational depositions in the open field (bulk deposition) ranged from 10.8 to 14.7 kg N ha(-1) a(-1) (throughfall: 11.3 to 12.3 kg N ha(-1) a(-1)) in the measuring years 1998 to 2000. Compared to these data, depositions in other forested areas of the Austrian Alps amounted to up to 30 kg N ha(-1) a(-1). The gravitational depositions (bulk deposition) alone--without considering dry and occult deposition slightly exceeded the lower limit of Critical Loads for coniferous and deciduous forests (>10 kg N ha(-1) a(-1)), but were below the Critical Loads for calcareous forests (15-20 kg N ha(-1) a(-1)).

The use of passive samplers for monitoring polycyclic aromatic hydrocarbons in ambient air

In this study polcyclic aromatic hydrocarbon (PAH) concentrations of ambient air are compared to those present in leaves, spruce sprouts and in the corresponding soil used as passive samplers. Marked profile alterations were detected in various soil horizons with increasing relative concentrations of higher boiling and decreasing relative concentrations of lower boiling PAH with depth. There is no direct correlation between the absolute PAH masses found in air samples and those collected by passive samplers or detected in corresponding soil samples. Even the PAH profiles differ significantly; they can, however, be correlated by introducing PAH- and sampler-specific factors. The PAH profiles appear to indicate that coal combustion mostly contributes to the PAH air pollution in the FRG. The time course of the concentration of benzo[a]pyrene and benzo[e]pyrene during the past seven years as measured with spruce sprouts as biological passive sampler indicate a significant decrease of the PAH concentration (by a factor of two) in the FRG. First measurements in a clean air area of the Eastern part of the FRG exhibited up to ten times higher PAH concentrations than found in comparable areas of the western part of the country.

Single and Combined Effects of Continuous and Discontinuous O3and SO2Immission on Norway Spruce Needles: I. Histological and Cytological Changes

Abstract For 22 months young Norway spruces (Picea abies Karst.) were separately and simultaneously exposed to a fumigation program, which was selected after the natural pollution values of O3 and SO2, both in clean-air areas and in industrial urban areas, had been determined. In all fumigation experiments we observed decreases in all histological parameters studied. Reductions in tissue areas and cell numbers of spruce needles were antagonistic after simultaneous exposures, simulating the clean-air area; those representing the industrial urban area were less than additive. Discontinuous fumigation with O3 separately and low constant-concentration exposure to SO2, overlapped by occasional peak concentration of SO2, had stronger reducing effects on vascular tissues than continuous fumigation with O3 of the same concentration or continuous fumigation with SO2, even with a higher concentration.

Peripheral clean air areas near industrial regions during smog weather conditions — Contribution to planning of industrial nearby clean air areas

Peripheral clean air areas near industrial regions during smog weather conditions — Contribution to planning of industrial nearby clean air areas

Total airborne mercury and its possible origin

Total airborne Hg as well as black particles (soot) were monitored in a number of clean air areas in Sweden. For some of the sampling sites, back trajectories for air movements at 850 mb were provided by the Norwegian Meteorological Institute. It is shown that the total Hg in air may be divided into two fractions. The most important one may be considered to be a background and is probably the result of re-emission of Hg by the ground and by natural water. The other fraction is highly dependent on wind direction in the same way as black particles. This fraction seems to be of anthropogenic origin.

Effects of Urban Air Pollution on School-Age Children

From November 1977 to March 1978, forced expiratory volumes (FEVs) of 78 second graders living in a high sulfur dioxide and smoke pollution area were compared with FEVs of 70 second graders living in a clean air area. The incidence of acute respiratory diseases in these children and their families was also comparatively studied during the same period. Indoor and outdoor measurements of sulfur dioxide and smoke, as well as additional measurements of suspended particulate matter (SPM) and sulfate were conducted. The results of the study suggest that at the actual average annual exposure to sulfur dioxide, smoke, and SPM of 70-80 microgram/m3, 60-80 microgram/m3, and 130-200 microgram/m3, respectively, with frequent exposures to three to five times higher daily sulfur dioxide and smoke concentrations and two times higher daily concentrations of SPM during the heating season, certain effects on the ventilatory functions and occurrence of acute respiratory diseases can be expected.

Emissions of arsenic in Sweden and their reduction.

The role of arsenic in Sweden is generally described, including raw materials, exports/imports, products, consumption, etc. An attempt was also made to estimate the transport of arsenic in Sweden. The quantities of arsenic in raw materials, the emissions of arsenic from such processes as copper smelters and chemical industries, and the amounts of products containing arsenic were calculated. The studies show that a copper smelter is the main user of arsenical materials, the very largest emitting source and also the plant which manufacturers most arsenic products. A summary of measurements of arsenic in air, water and soil in Sweden has also been made. The concentrations near a smelter, in the Baltic, in cities and in "clean-air areas" are given. The efforts made to date to reduce the emissions of arsenic and the measures planned for the next few years are described. A reduction has already been achieved and a further rather large decrease will come, especially in arsenic levels in water. The possibilities of minimizing the use of materials and products containing arsenic is also discussed.

The application of the linear system theory of visual acuity to visibility reduction by aerosols

The basic ideas and limitations of the linear system theory of visual acuity are presented. It is shown that under most conditions the visual range of contrast detail, such as trees on a distant hillside, can be predicted by linear system theory. An example of the method is given. One result is that the visual range of contrast detail is not in general inversely proportional to the extinction coefficient of the atmosphere, as the classical theory predicts. This effect is due to the nonlinear response of the eye to the changing visual angle presented by the target as its distance increases. The implications to studies relating nephelometer readings and visual range are discussed. It is also shown that significant, noticeable degradation of visibility in clean air areas can occur with only a very small absolute increase in the attenuation coefficient due to pollution.

Carbon monoxide in the biosphere: Sources, distribution, and concentrations

Carbon monoxide, the most abundant air pollutant found in the community atmosphere, generally exceeds the mass of all other air pollutants combined (excluding CO2). Total annual tonnages of CO from man-made sources exceeded 132 × 106 metric tons (146 × 106 short tons) in the United States and 359 × 106 metric tons (396 × 106 short tons) globally in 1970. The largest single technological source of CO is the internal combustion engine. The atmospheric CO abundance in the biosphere in urban areas, where man resides, is not uniformly distributed and is dominated by anthropogenic sources. Community concentrations are quite variable and unequally distributed, being related to proximity to anthropogenic sources, patterns of human activity, and meteorological factors. These concentrations range from about 1 to >70 ppm and have brief peak levels in dense traffic as high as 140 ppm. The removal of CO from the atmosphere, as well as the sources and dispersion, controls the local concentration. Temporal characteristics of community CO concentrations are described. Although localized buildup of CO in cities may still represent a serious health hazard, man's CO production considered on a global basis is relatively minor in comparison with production from the larger natural sources. These include the atmospheric oxidation of methane, the ocean, decay of chlorophyll in plants, and terpene oxidation from plant sources. Their total source strength is estimated as 3–25 times the man-made sources in the atmosphere as a whole. Background concentrations, a product of both natural and anthropogenic sources, normally range from 0.04 to 0.20 ppm, occasional concentrations being as high as 0.80 ppm at ground level in remote clean air areas, the higher concentrations being found in the northern hemisphere.