Level Of Air Contamination Research Articles

Geographical distribution of benzene in air in northwestern Italy and personal exposure.

Benzene is a solvent strictly related to some industrial activities and to automotive emissions. After the reduction in lead content of fuel gasoline, and the consequent decrease in octane number, an increase in benzene and other aromatic hydrocarbons in gasoline occurred. Therefore, an increase in the concentration of these chemicals in the air as primary pollutants and as precursors of photochemical smog could occur in the future. The objectives of this study were to describe the benzene air pollution at three sites in northwestern Italy throughout 1991 and 1994; to examine the relationship between benzene air pollution in indoor, outdoor, and personal air as measured by a group of nonsmoking university students; and to determine the influence of environmental tobacco smoke on the level of benzene exposure in indoor air environments. The results indicate a direct relationship between population density and levels of contamination; an indoor/outdoor ratio of benzene air pollution higher than 1 during day and night; a similar level of personal and indoor air contamination; and a direct relationship between levels of personal exposure to benzene and intensity of exposure to tobacco smoke. Human exposure to airborne benzene has been found to depend principally on indoor air contamination not only in the home but also in many other confined environments.

Estimating spatial distribution of exposure by integrating radiotelemetry, computer simulation, and geographic information system (GIS) techniques

Abstract The presence of native wildlife species at a chemical production facility provides an interesting opportunity to assess the movement, uptake, and potential impact of pollutants in the environment. Representatives of a wildlife species that serve as sentinels for adverse health effects can be captured and radio collared to determine their movement patterns and home range by telemetry. Data on the characteristics of the point source air release were used in a Gaussian plume model to provide estimates of ambient air contaminant levels. These concentration and telemetry data were then mapped spatially using land use/land cover data in a geographic information system (GIS) to develop an integrated exposure estimate. This was then used to predict study areas that may be of ecological concern and that may warrant further investigation for potentially adverse effects in wildlife populations at other contaminated sites.

Air contamination following aerosol ventilation in the gamma camera room

Air contamination levels arising from lung aerosol ventilation studies have previously been monitored [1]. Residence time in the room used for ventilation was perceived to be an important factor in dose received. This study was designed to assess air contamination levels when ventilation and imaging are carried out in the same room. Air samples were taken before, during and after aerosol administration, over 24 studies where a mouthpiece was used. The mean airborne contamination during administration was 4.39 kBq m-3, implying an effective dose equivalent (EDE) to the operator from inhaled activity of 0.004 microSv. Measurements made during studies on three patients where a mask was used gave a mean EDE of 0.065 microSv (the highest EDE was 0.08 microSv). Ten minutes after nebulizing had stopped, the contamination had reduced to background levels in all but two cases; in these cases, the levels were less than 1.1 kBq m-3. Aerosol ventilation in the gamma camera room does not constitute a significant radiation hazard to staff. Patient compliance is an important factor in minimizing doses. Clear instructions and practice are a vital part of the procedure.

Cost-Effective Strategies to Control Radon in Residences

Many control strategies can be used to address health and comfort concerns posed by high levels of indoor air contaminants. Sufficient experience exists to develop models that estimate the effectiveness and cost of radon (Rn) mitigation strategies in single-family houses. In this paper, cost curves are developed that use one or several control strategies to achieve a range of concentration reductions. The results indicate preferred “cost-optimal” strategies at various mitigation levels. Rn control strategies considered include sealing, block-wall ventilation, subslab ventilation, drain-tile ventilation, ventilation with and without heat recovery, and water treatment. For a case-study residence typical of U.S. single-family homes, cost-effective control is provided by sealing soil-gas entry routes, block-wall ventilation, and heat-recovery ventilation. Other strategies can provide similar Rn reductions, but at higher costs. The sensitivity of results to climate and energy-price assumptions is explored. Identifying strategies that are cost-effective will help to increase their use and reduce risks.

Total exposure from outdoor and indoor air pollution in the Aretic

Most of the chemical contaminants and radionuclides that have been identified in the arctic environment are known to have toxic, genotoxic, or carcinogenic endpoints in humans. However, knowledge is lacking on the health effects of exposure to low concentrations of mixtures of the contaminants in various periods of a lifetime, in utero included. Therefore, more detailed study is needed on the implications of present levels of air and food contamination for human health in arctic and subarctic regions, as part of ongoing environmental monitoring programs. Here we outline the prerequisites and precautions for such studies, in particular the rationale for a total human exposure approach. We emphasize using a concept of total exposure and dose analysis (TEDA), covering integration of (1) environmental monitoring, (2) personal monitoring, (3) biological monitoring, (4) analysis of selected biomarkers of individual susceptibility and pre-stages of disease, (5) evaluation of functional changes and adverse health effects reflecting human exposure, and (6) information collected from interviews and questionnaries, taking bias and potential confounders into account.

Air contamination in umbilical cord blood gas sampling

Our purpose was to determine the effect of air contamination and the length of time before assay on umbilical cord blood gases at delivery. Umbilical venous cord blood gases (0.5 ml) were drawn from 21 patients at delivery in 1 and 3 ml heparinized syringes with varying amounts of air contamination (none, 0.5 ml air admitted and removed from the syringe, and 0.5 ml of air retained). In an additional 15 patients the 0.5 ml sample was contaminated with 0.1, 0.2, 0.3, 0.4, and 0.5 ml of air. Air contamination had no effect on pH, PCO2, or bicarbonate but did increase the PO2 when the residual air was > 37.5% in a 3 ml syringe. No changes occurred in a 1 ml syringe. Time from drawing the blood to assay did not significantly alter the results. Umbilical cord blood gases are best drawn in 1 ml heparinized syringes. Only if the residual air contamination exceeds 37.5% will PO2 increase. The level of air contamination will not alter the evaluation of fetal-neonatal acidosis.

Benzene, toluene and xylenes in air, geographical distribution in the Piedmont region (Italy) and personal exposure

The objectives of this study were the determination of: (a) benzene (B), toluene (T) and xylene (X) air pollution in three sites of the Piedmont region (north-western Italy), (b) the relationship between BTX pollution in indoor, outdoor and personal air measured for a group of non-smoking university students, (c) the influence of environmental tobacco smoke on the level of BTX exposure for indoor air environments. Results indicate (i) a direct relationship between human density and level of contamination and higher toluene pollution, (ii) an indoor/outdoor ratio of > 1 for all the three aromatics, (iii) a similar level of personal and indoor air contamination. Human exposure to BTX air pollution has been found to depend principally on indoor air contamination, not only on home pollution, but also, probably on many other confined environments.

Thermally Induced Ventilation of Livestock Transporters

Livestock require ventilation during transport to ensure acceptable air temperatures, humidities and contaminant levels. Provision of ventilation in pig, sheep and cattle vehicles is usually through apertures positioned along the sides. Air exchange through these apertures occurs by forced ventilation, from vehicle motion or wind, or by thermally induced ventilation, generated by heat from the animals causing internal to external air temperature differences. Thermally induced ventilation is always present, but forced ventilation may be intermittent; particularly for a stationary vehicle on an enclosed roll-on roll-off ferry deck which prompted this study. Thus, to ensure adequate ventilation at all times, design calculations should be based on thermally induced ventilation. A model is presented which takes into account thermally induced ventilation through slot openings, heat transfer through the structure of the vehicle and heat, moisture and carbon dioxide output of the animals. Predictions of vehicle internal air temperature show this to be very insensitive to vehicle characteristics, species, heat output and stocking density. This arises because the ventilation is caused by the animal heat increasing the vehicle internal air temperature and consequently increasing the internal to external air temperature difference. For a given vent area, reducing stocking density, and thus animal heat, reduces the ventilation rate resulting in an internal air temperature which is largely self compensating. Comparison of predicted results with measurements made on a ferry voyage show agreement of vehicle internal air temperature to better than ±1°C and relative humidity to +6%.

Current Levels of Air Contaminants in Indoor Air in Europe: A Review of Real Situations

There is little published work on the various pollutants found in indoor air in Europe, and many significant pollutants such as benzo[a]pyrene have hardly been measured at all. Practically all of the work relates to Western Europe with very little from Eastern Europe. This review brings together what is known through a thorough review of the European literature on indoor air quality (IAQ) since 1982. The complete database does not include estimates of IAQ that have been made by modelling or measured in artificial environments but only those made in real environments. The scope of the review has been lim ited to studies of the inorganic compounds produced by the combustion of organic matter. The compounds have been measured in homes, public places, 'bars' and transport and further subdivided, where possible, into smoking and non-smoking areas.

U.S. Approach for Air Sampling of Workplace Contaminants: Current Basis and Future Options

Abstract The evaluation and control of the workplace environment and worker exposures to air contaminants require an understanding of the levels of those air contaminants. In the past 20 years, the emphasis has been on monitoring specific chemical vapors and aerosols. The approach that has been taken, the reason for that approach, and the progress that has been made are the primary topics of this article. Another topic of this article concerns the future of workplace monitoring with regard to new instrumentation, instrument and computer networking, the growth of biotechnology, and concerns about indoor/office environments and the agriculture setting. Bierbaum, P.J.; Doemeny, L.J.; Smith, J.P.; Abell, M.T.: U.S. Approach for Air Sampling of Workplace Contaminants: Current Basis and Future Options. Appl. Occup. Environ. Hyg. 8(4):247-250; 1993.

AIR CONTAMINANT DISTRIBUTIONS IN A COMMERCIAL LAYING HOUSE

ABSTRACT Total particle counts (TPC), carbon dioxide (CO2) levels, ammonia (NH3) levels, and room air temperature were monitored in a commercial cage laying house in Pennsylvania. The inlet and the exhaust were monitored for 24-h periods once a week from July 1989 to February 1990 while six other sampling locations in the house were monitored for 24-h periods once each six weeks. At each sampling location, air contaminant levels were measured at the alley and at each of the four cage decks. Results showed that more than 99% and 97% of total particles were smaller than 10.0 and 5.0 |im in diameter, respectively. TPC, CO2 levels, NH3 levels, and air temperature exhibited day-to-day variations but bird age effect was not significant. Mean daily TPC, CO2 levels, NH3 levels, and temperature ranged from 18 to 103 particles/mL, 553 to 4424 ppm, 9 to 54 ppm, and 17° to 30° C, respectively. Overall air quality was observed to be poorer at locations most distant from the exhaust fans. There were significant differences among locations in NH3 levels and temperature but there were no significant differences in TPCs and CO2 levels. Ventilation rate appeared to be the most important factor influencing indoor air quality. Mean TPCs were significantly higher while mean CO2 and NH3 levels were significantly lower in hot weather than in cold weather. CO2 levels and NH3 levels were highly correlated but there was little correlation between TPCs and the levels of CO2, NH3, or air temperature.

Lung Health Consequences of Reported Accidental Chlorine Gas Exposures among Pulpmill Workers

The long-term consequences of accidental chlorine gas exposure have been investigated, mainly in the community setting, among persons exposed as a result of a nearby chlorine spill. This circumstance is not analogous to the more frequent chlorine or chlorine dioxide gas overexposures that occur commonly in pulpmills over a background of a low level of gas exposure. To investigate the respiratory health consequences of these accidental exposures ("chlorine gassing") in the industrial setting, we carried out a cross-sectional respiratory health survey among workers at a British Columbia coastal pulpmill and a nearby rail maintenance yard. A greater proportion of pulpmill workers were unavailable for study because of illness (10.5% versus 2.4% in the railyard, p less than 0.01). Procedures involved simple spirometry, respiratory symptom assessment, and measurement of average levels of air contaminants. Average chlorine levels in the pulpmill were below 1 ppm; however, 60% of the pulpmill workers reported one or more accidental "chlorine gassing" incidents. Pulpmill workers who reported being "gassed" were significantly more likely to report wheezing on occasion than were other pulpmill workers and railyard workers (rate for these three groups: nonsmokers: 8, 2, 1%; ex-smokers: 17, 11, 7%; current smokers: 42, 21, 19%; p less than 0.05). No significant lung function differences were found between the overall pulpmill group and the railyard workers; however, nonsmoking and formerly smoking pulpmill workers who reported being "gassed" had significantly lower average midmaximal flow rate and FEV1/FVC ratio than did their counterparts in the remainder of the pulpmill population (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Air contamination during total hip arthroplasty in an ultraclean air enclosure using different types of staff clothing

Air contamination was measured in a down-flow, clean air enclosure during 50 total hip arthroplasties to compare the effect of different scrub suits and operating gowns. In one series, with cotton clothes, the operating gowns used were either disposable nonwoven operating gowns or total body exhaust gowns. With the exhaust gowns the median air contamination, measured as colony-forming units (cfu)/m 3, was reduced by about 5 times, to 0.3. In another series, nonwoven operating gowns were used together with scrub suits made of either cotton or one of two types of synthetic materials. The latter two scrub suits were equipped with elastic sealings at the openings. With both of these types the median air contamination, compared to cotton scrub suits, was reduced by about one half, to 0.4 cfu/m 3. The authors conclude that both specially designed scrub suits and exhaust gowns can further reduce an already low level of bacterial air contamination in a down-flow, clean air enclosure.

Lower respiratory symptoms in children exposed to nitrogen dioxide from unvented combustion sources

A prospective epidemiologic study was carried out for 12 weeks in the winter of 1983 to evaluate the impact of indoor air contaminant levels on respiratory health. A group of 121 children below the age of 13 (59 with unvented kerosene space heaters in the home; 62 without) were enrolled in the study and nitrogen dioxide levels were measured in 93% of the subjects' homes for one two-week period. When socioeconomic status and history of respiratory illness were controlled, children under the age of seven exposed to 30 μg/m 3 or more of nitrogen dioxide were found to have a risk of reporting lower respiratory symptoms 2.25 times (95% C.I. 1.69–4.79) that of children who were not exposed. Aspects of our study design, including increased precision of exposure classification and the inclusion of very young children, may explain our findings.

Assessment of exposure to indoor air contaminants from combustion sources: methodology and application.

A methodology for assessing indoor air pollutant exposures is presented, with specific application to unvented combustion by-products. This paper describes the method as applied to a study of acute respiratory illness associated with the use of unvented kerosene space heaters in 333 residences in the New Haven, Connecticut, area from September 1982 to April 1983. The protocol serves as a prototype for a nested design of exposure assessment which could be applied to large-scale field studies of indoor air contaminant levels. Questionnaires, secondary records, and several methods of air monitoring offer a reliable method of estimating environmental exposures for assessing associations with health effects at a reasonable cost. Indoor to outdoor ratios of NO2 concentrations were found to be 0.58 +/- 0.31 for residences without known sources of NO2. Levels of NO2 were found to be comparable for homes with a kerosene heater only and those with a gas cooking stove only. Homes with a kerosene heater and a gas stove had average two-week NO2 levels approximately double those with only one source. Presence of tobacco smokers had a small but significant impact on indoor NO2 levels. Two-week average levels of indoor NO2 were found to be excellent predictors of total personal NO2 exposure for a small sample of adults. Residences with kerosene space heaters had SO2 levels corresponding to the number of hours of heater use and the sulfur content of the fuel. Formaldehyde levels were found to be low and not related to unvented combustion sources. NO2, SO2, and CO2 levels measured in some of the residences were found to exceed those levels specified in current national health standards.

“Exposure to isoflurane vapours in operating theatres: A comparative study”

Pollution and chronic exposure to waste anaesthetic gases may be a serious problem for operating theatre personnel. The authors reported the air contamination levels of isoflurane in the operating and preparation rooms at Clinica Chiruryica Veterinaria (University of Milan) and compared them with those of methoxyflurane, halothane and enflurane, previously detected in the sailie rooms.

Residential Air Pollution from Kerosene Heaters

The studies provide data on pollution emissions from kerosene heaters operated under laboratory conditions for short time periods. The need for data on pollutant levels resulting from the residental use of unvented kerosene heaters prompted the investigation. Air contaminant levels were greater than recommended guidelines and therefore could be presumed to pose a health risk to susceptible individuals. (1 table)(DP)

Residential air-to-air heat exchangers: Performance energy savings, and economics

Residential energy consumption can be decreased if air infiltration is reduced by constructing houses more tightly. In some cases, however, reduced air infiltration can lead to problems with indoor air quality ( e.g., excess humidity and high levels of indoor-generated air contaminants). One solution to this problem is to install a residential air-to-air heat exchanger. The heat exchanger provides a controlled supply of ventilation which counteracts the adverse effects of reduced infiltration. In addition, the heat exchanger recovers much of the energy that would normally be lost when ventilation occurs by air infiltration. Thus, by employing heat exchangers in low-infiltration houses, it is possible to save energy without sacrificing indoor air quality. This paper discusses the performance of residential heat exchangers and summarizes results from tests of several models. It also compares the energy consumed, during the heating season, in low-infiltration houses with heat exchangers, with the energy consumed in typical houses in four cities throughout the United States. For each city, a cost-benefit analysis is performed from the point of view of a home-owner. Houses with natural gas, oil, and electrical heating systems are considered. Our analysis indicates that the energy required to heat ventilation air in homes employing heat exchangers is 5.3 – 18.0 GJ less than the energy required to heat ventilation air in typical homes. In homes with heat exchangers, the heat exchanger's fan system required 2.2 – 3.6 GJ of electrical energy during the heating season. The net present benefit for homes employing heat exchangers, when compared with typical homes, ranged from —$1350 to +$2400 and discounted payback periods ranged from five to over 30 years. The cost-effectiveness of employing heat exchangers was found to be highly affected by climate, type of heating fuel, heat exchanger performance, and ventilation rate.

Airborne bacteria and surgical infection

From the inception of modern surgery, the significance of airborne microbes to surgical infection has been controversial. The success of aseptic methods led the majority of surgeons early in this century to discount the airborne route. Despite aseptic disciplines, a significant level of infection continued and from 1930 onwards renewed attention was directed towards the air. Many studies over the following 25 years produced anecdotal and suggestive evidence that this was relevant and that a reduction in surgical sepsis followed a reduction in the numbers of airborne bacteria in the operating room. To this day, however, there has been no wholly satisfactory demonstration of this. Such a demonstration requires comparison of the outcome of a considerable number of surgical operations performed during the same period by the same surgeons under conditions which differ only in the levels of air contamination. Recent developments in orthopedics have resulted in large numbers of essentially similar operations on a site susceptible to infection but free from sources of bacteria within itself. Under these conditions, there is evidence that the numbers of bacteria contaminating the wound at the end of the procedure are substantially fewer when the levels of airborne bacteria are reduced.

Monitoring of I excretions and used materials of patients treated with 131I.

The maximum excretion rates of iodine in exhalation, perspiration and salivation were measured in patients treated with /sup 131/I for thyroid carcinoma and hyperthyroidism. The contamination of dishes, chopsticks, toothbrushes, linen (coversheets), sheets and towels, and underwear (shirts and drawers) were monitored and evaluated along with the air contamination level arising from these items. The maximum excretion rate of the administered dose on an average was 3.2 x 10/sup -6/ per hr in exhalation, 2.45 x 10/sup -6/ per hr in perspiration, and 6.3 x 10/sup -3/ per ml. in salivation. The maximum contamination rate of items ranged from 1.1 x 10/sup -3/ to 10/sup -5/ of the administered dose. The predominant radioactivity of the skin surface resulted from perspiration with a maximum of 1.8% evaporation into the air as water vapor. The air contamination level ranged from 1.4 x 10/sup -5/ to 1.2 x 10/sup -7/ per hr of the administered dose.