Smoke-free cafe in an unregulated European city: highly welcomed and economically successful.

OBJECTIVE: In a unique setting with two identical cafes, which only differed in their smoking ordinances, this study assessed the influence of smoking policies on the choice of the cafe, investigated regulatory preferences among customers, and evaluated the claim that smoking cafes have better sales performance in a city without smoking bans. METHODS: In a parallel assessment, customers of both cafes answered a questionnaire. Sales were compared and air pollutants were measured to confirm air quality differences. RESULTS: The two customer groups (n = 177) differed only with regard to smoking status (p < 0.01). The smoking regulation was the most often cited selection criterion (83%). In the non-smoking café, 89% indicated that they were usually annoyed by smoke in coffee houses, and 62% would avoid or leave cafes for this reason. Two thirds stated that all cafe/restaurants should offer the opportunity of a smoke-free environment. However, almost half stated that mandatory regulations are not needed and that customers should make individual arrangements based on tolerance and courtesy. Those who were informed about the health effects of secondhand smoke were more likely to call for clear policies. Whereas sales showed no differences, tips were 22% (p < 0.001) higher in the non-smoking cafe. CONCLUSION: In a generation raised in smoking friendly environments, customers paradoxically ask for a landmark shift towards smoke-free opportunities, while substantially adhering to the tobacco industry paradigm of promoting "tolerance" rather than smoke-free policies. Given the clear preference of a large number of customers, hospitality businesses could, however, greatly profit from offering smoke-free environments even in the absence of regulatory policies.

Air pollutants enhance rhinoconjunctivitis symptoms in pollen-allergic individuals.

BACKGROUND: Little is know about the relation of airborne pollen allergens to nasal and ocular symptoms in combination with air pollutants. OBJECTIVE: The hypothesis was that air pollutants exacerbate allergic symptoms of the nose and eyes during the pollen season. In addition, the use of allergen measurements instead of pollen counts should be tested. METHODS: Fifteen pollen-allergic, nonsmoking subjects with weak reactivity of the airways recorded rhinoconjunctival symptoms and medication every morning and evening throughout the pollen season. Symptoms were compared with air pollutants (nitrogen oxide [NOx], particulate matter smaller than 10 microm, and ozone) and birch and grass pollen counts or, alternatively, to airborne birch and grass allergens determined using ELISA-techniques. A multiple linear regression model was used which controlled for autocorrelation of the residuals of the time series (Cochrane-Orcutt approach). This model was applied to each subject individually, followed by calculations of summary scores for the group. RESULTS: Air pollution levels were moderate, often meeting air quality standards. Effect estimates (increase of score with 10-fold increase of concentration) were NOx = 1.06, P < 0.01; ozone = 1.59, P < 0.01; and pollen = 0.48, P < 0.001. Using allergen concentrations instead of pollen counts resulted in similar effect estimates. Using particulate matter smaller than 10 microm instead of NOx gave comparable but less consistent results. CONCLUSIONS: Symptoms were related to moderate levels of pollutants, suggesting that rhinoconjunctival tissue is very sensitive to irritant stimuli during an ongoing allergic inflammation, and that susceptibility toward allergens might be increased in areas with increased levels of air pollutants. Allergen measurements seem equally usable as pollen counts to investigate rhinoconjunctivitis.

Acute sensory responses of nonsmokers at very low environmental tobacco smoke concentrations in controlled laboratory settings.

The objective of this study was to provide a basis for effectively protecting nonsmokers from acute sensory impacts and for preventing deterioration of indoor air quality caused by environmental tobacco smoke (ETS) emissions. With an olfactory experiment we determined odor detection thresholds (OT) of sidestream ETS (sETS), and with a full-body exposure experiment we investigated sensory symptoms at very low sETS exposure concentrations. OT concentrations for sETS are three and more orders of magnitude lower than ETS concentrations measured in field settings and correspond to a fresh air dilution volume of > 19,000 m(3) per cigarette, over 100 times more than had previously been suggested for acceptable indoor air conditions. Eye and nasal irritations were observed at one order of magnitude lower sETS concentrations than previously reported, corresponding to a fresh air dilution volume of > 3,000 m(3) per cigarette. These findings have great practical implications for defining indoor air quality standards in indoor compartments where ETS emissions occur. Our study strongly supports the implementation and control of smoking policies such as segregating smoking areas from areas where smoking is not permitted or instituting smoking bans in public buildings.

Short-term variation in air pollution and in average lung function among never-smokers. The Swiss Study on Air Pollution and Lung Diseases in Adults (SAPALDIA).

The present analysis was directed at investigating associations between short-term variations in air pollutant levels (NO2, total suspended particulates [TSP], O3) and cross-sectional lung function (FVC, FEV1, and forced expiratory flow at 25% to 75% of FVC [FEF25-75]) within a random sample of 3,912 adult never-smokers from eight areas of Switzerland (i.e., participants in the Swiss Study on Air Pollution and Lung Diseases in Adults [SAPALDIA] cross-sectional study, 1991). Within each local data set, the logarithms of FVC, FEV1, and FEF25-75 were regressed against the 24-h-means of NO2 and TSP and the 8-h mean of O3 (10:00 A.M. to 6:00 P.M.) on the examination day, with control for subjects' sex, age, height and weight, seasonal fluctuations and weekly cycles and meteorologic factors. On average, a 10-microg/m3 increment in the daily level of NO2, TSP, and O3 was associated with decrements in FEV1 of 0.67% (95% confidence interval [CI]: 0.13% to 1.21%), 0.46% (95% CI: 0.14% to 0.78%), and 0.51% (95% CI: 0.13% to 0.88%), respectively. Moreover, 10-microg/m3 increments in NO2 and TSP were associated with decrements in FVC of 0.73% (95% CI: 0.22% to 1.23%) and 0.36% (95% CI: 0.06% to 0.66%), respectively, and a 10-microg/m3 increment in O(3) was associated with a decrement in FEF25-75 of 1.04% (95% CI: 0.22% to 1.85%). Our results suggest that FVC, FEV1, and FEF25-75 vary with the daily level of NO2, TSP, and O3, but that these measures of lung function do not allow separation of the effects of particulates from those of NO2.

Personal pollen exposure compared to stationary measurements.

The aim of this study was to examine to what extent stationary outdoor pollen measurements are representative for estimating personal exposure to pollen. Ten subjects were studied during a total of 36 days in spring and summer Pollen was sampled using personal SKC total dust samplers and stationary Burkard pollen traps. The personal activity pattern was recorded quarter-hourly as well as the time spent outdoors. As a reference, SKC and Burkard samplers were run stationary and in parallel. Stationary comparison of the samplers showed good correlation (r = 0.981, p <0.001). However, the SKC sampler collected systematically about four times less pollen than the Burkard sampler. Taking into account the systematic difference between the sampling devices, the personal exposure data were about 30% of the stationary pollen concentrations with significant correlation (log-transformed data, r = 0.719, p <0.0001). Considering the average time the subjects spent outdoors (14% of sampling time), the indoor-outdoor ratio for pollen was 0.2. In conclusion, pollen reports are reliable for estimating personal exposure over a limited time period although personal pollen exposure is much lower.

Validity of annoyance scores for estimation of long term air pollution exposure in epidemiologic studies: the Swiss Study on Air Pollution and Lung Diseases in Adults (SAPALDIA).

In air pollution epidemiology, estimates of long term exposure are often based on measurements made at one fixed site monitor per area. This may lead to exposure misclassification. The present paper validates a questionnaire-based indicator of ambient air pollution levels and its applicability to assess their within-area variability. Within the framework of the SAPALDIA (Swiss Study on Air Pollution and Lung Diseases in Adults) cross-sectional study (1991), 9,651 participants reported their level of annoyance caused by air pollution on an 11-point scale. This subjective measure was compared with annual mean concentrations of particulate matter less than 10 microm in diameter (PM10) and nitrogen dioxide. The impact of individual factors on reported scores was evaluated. Nitrogen dioxide concentrations at home outdoors (measured in 1993), smoking, workplace dust exposure, and respiratory symptoms were found to be predictors of individual annoyance scores. Regression of population mean annoyance scores against annual mean PM10 and nitrogen dioxide concentrations (measured in 1993 and 1991, respectively) across areas showed a linear relation and strong correlations (r>0.85). Analysis within areas yielded consistent results. The observed associations between subjective and objective air pollution exposure estimates suggest that population mean scores, but not individual scores, may serve as a simple tool for grading air quality within areas. Reported annoyance due to air pollution should be considered an indicator for a complex environmental condition and thus might be used for evaluating the implementation of environmental policies.

Differences in size selective aerosol sampling for pollen allergen detection using high-volume cascade impactors.

BACKGROUND: Assessment of the allergen content of airborne particles small enough to reach the bronchiolar airways is important for a better understanding of allergic asthma. OBJECTIVE: In order to test the performance of a high-volume cascade impactor for size-selective sampling of airborne particles, the characteristics of pollen deposition, and the particle size-dependent allergen distribution, were re-examined. METHODS: Two cascade impactors with rectangular slots were run in parallel, one with glass fibre filters on all stages, the other with silicone grease on stage 2 (collection of particles of size 4.2-10.2 micrometer) instead. Pollen was counted using light microscopy and allergens were measured using ELISA techniques. RESULTS: In the impactor without the greased stage 2, a heavy bounce and blow-off for pollen was found. Bounced pollen was deposited mainly on the back-up filter, the sampling stage for particles smaller than 1.4 micrometer. However, if stage 2 was coated with silicone grease, less than 1% of total pollen was found in the lower stages. On the first stage of the sampler (50% cut-point, 10.2 micrometer) where all pollen should impact, pollen had a deposition efficiency of only 24-47%, depending on the abundant pollen species. Much less allergen was found in fine particle fractions than in previous studies in which particles were sampled with similar samplers but without grease as a pollen trap. CONCLUSIONS: The observed bounce and blow-off of pollen without a greased stage 2 leads to serious mistakes when assessing the allergen content of the fractions collecting particles smaller than intact pollen, i.e., below 10.2 micrometer. Pollen allergen concentrations in respirable particle fractions are much lower than in the pollen size fraction. This is of great importance both for symptoms of sensitized allergic asthmatics and for research of asthma-related mechanisms.

An assessment of indoor air contaminants in buildings with recreational activity.

Indoor air quality measurements were carried out during three concerts and one ice hockey game in three different halls. Gas phase components consisted of CO2, CO, and NO whereas for particulate indicators, measurements of particle mass distributions (0.05-9 microm), particle number distributions (0.75-10 microm), and particle bound polycyclic aromatic hydrocarbons (pPAH) were carried out. The calculated ventilation rates did not meet the ventilation requirements for rooms with occupants who smoke to be perceived as acceptable by 80% of the occupants. Average PM9 (mass of particulate matter with an aerodynamic diameter < 9 microm) concentrations throughout the events ranged from 318 to 2000 microg m(-3). Particle concentrations in the size range < 0.4 microm measured 203-696 microg m(-3), the majority of it being attributed to environmental tobacco smoke (ETS). For particle numbers > 0.75 microm concentrations ranged from 2 x 10(4) to 1.9 x 10(5) particles per l while for pPAH, concentrations from 336 to 990 ng m(-3) were observed. The average event concentrations for the gaseous component CO2 ranged from 1110 to 1700 ppm, for CO 2-3.1 ppm and for NOx 237 ppb. The event to baseline concentration ratios for gaseous components ranged from 1.1 to 4.3 while for particulate indicators generally much greater ratios between 0.7 and 140 were found. Possible health effects inflicted by an exposure based on the measured concentrations of the various parameters are discussed.

Bioaerosols in ambient air particulates: a review and research needs.

Fine (< 2.5 microns) and inhalable (< 10 microns) ambient particles are associated with increased morbidity and mortality. In addition to a variety of organic chemicals, salts, and metals, inhalable ambient particles may contain biological species, such as proteins, lipids, and so on, from plants, bacteria, and fungi. In airborne particles, the total mass of biological species is small, but their allergenic and inflammatory potential is strong. This paper provides an overview of the bioaerosols found in ambient air particles. Pollen grains are the strongest aeroallergens and have a size > 10 microns. Major pollen allergens have also been identified in size fractions smaller than that of intact pollen. Special atmospheric conditions (such as rainfall) or interactions between air pollutants and pollen may produce allergenic fine particles. Endotoxin (LPS), another important biological species of particles, may play a role in proinflammatory effects. In this review, we discuss the possible interactions between pollen and pollutants and suggest several directions for future research.

[Endotoxins in the workplace and in the environment]. / Endotoxine in Arbeitswelt und Umwelt.

Endotoxins, cell-wall fragments of gram-negative bacteria, are found in various work environments and first measurements have been made in general indoor environments. Endotoxins cause an inflammatory response of the respiratory tract. The response is mediated by the proinflammatory cytokines IL-1, IL-6, IL-8, and TNF-alpha and gives rise to general symptoms (fever, headache, malaise), respiratory symptoms (tightness of chest, dry cough), and lung function decrements. In the work environment endotoxins have been identified in all environments which produce similar symptoms. The qualitative results of experimental and epidemiological studies agree well. The related question whether endotoxins are the biologically active component of organic dust cannot yet be answered because of the gap between the concentration of lipopolysaccharides and of endotoxins necessary to induce the same quantitative effect. Different possible explanations are discussed. Endotoxins are also found in the general environment, especially indoors. Their health relevance needs to be assessed in more detail, especially in subjects with bronchial hyperreactivity.

Long-term ambient air pollution and respiratory symptoms in adults (SAPALDIA study). The SAPALDIA Team.

The association between long-term exposure to ambient air pollution and respiratory symptoms was investigated in a cross-sectional study in random population samples of adults (aged 18 to 60 yr, n = 9,651) at eight study sites in Switzerland. Information on respiratory symptoms was obtained with an extended version of the European Community Respiratory Health Survey questionnaire. The impact of annual mean concentrations of air pollutants was analyzed separately for never-, former, and current smokers. After controlling for age, body mass index, gender, parental asthma, parental atopy, low education, and foreign citizenship, we found positive associations between annual mean concentrations of NO2, total suspended particulates, and particulates of less than 10 micrometers in aerodynamic diameter (PM10) and reported prevalences of chronic phlegm production, chronic cough or phlegm production, breathlessness at rest during the day, breathlessness during the day or at night, and dyspnea on exertion. We found no associations with wheezing without cold, current asthma, chest tightness, or chronic cough. Among never-smokers, the odds ratio (95% confidence interval) for a 10 micrograms/ m3 increase in the annual mean concentration of PM10 was 1. 35 (1.11 to 1.65) for chronic phlegm production, 1.27 (1.08 to 1.50) for chronic cough or phlegm production, 1.48 (1.23 to 1.78) for breathlessness during the day, 1.33 (1.14 to 1.55) for breathlessness during the day or at night, and 1.32 (1.18 to 1.46) for dyspnea on exertion. No associations were found with annual mean concentrations of O3. Similar associations were also found for former and current smokers, except for chronic phlegm production. The observed associations remained stable when further control was applied for environmental tobacco smoke exposure, past and current occupational exposures, atopy, and early childhood respiratory infections when restricting the analysis to long-term residents and to non- alpine areas, and when excluding subjects with physician-diagnosed asthma. The high correlation between the pollutants makes it difficult to sort out the effect of one single pollutant. This study provides further evidence that long-term exposure to air pollution of rather low levels is associated with higher prevalences of respiratory symptoms in adults.

Cytotoxicity and induction of proinflammatory cytokines from human monocytes exposed to fine (PM2.5) and coarse particles (PM10-2.5) in outdoor and indoor air.

Increased incidence of mortality and morbidity due to cardiopulmonary complications has been found to associate with elevated levels of particulate air pollution (particulate matter with an aerodynamic diameter < 10 microm, PM10 and <2.5 microm, PM2. 5). Lung injury and an imbalance of inflammatory mediators are proposed causative mechanisms, while the toxic constituents may be acidity, transition metals, organic, and biogenic materials. To compare the ability of inhalable fine particles (PM2.5), and coarse particles (PM10-2.5) to cause cell injury and cytokine production in monocytes, dichotomous Andersen samplers were used to collect size-fractionated PM10 for in vitro testing of the particle extracts. Particles from both outdoor and indoor air were collected onto Teflon filters, on nine separate occasions. Each filter was water extracted and each extract assessed for ability to cause cell death, as well as interleukin (IL)-6 and IL-8 production in human monocytes. Significant toxicity and cytokine production was induced by outdoor PM10-2.5, but not by outdoor PM2.5 or the particles collected indoors. Outdoor PM10-2.5 induced 20 times the amounts of IL-6 and IL-8 than the fine particles. Cytotoxicity was inhibited by deferoxamine, a chelator of transition metals, while cytokine production was not. On the other hand, lipopolysaccharide binding protein (LBP) completely inhibited cytokine induction by PM10-2.5, suggesting that gram-negative bacteria and/or endotoxins are components of PM10-2.5. The effective proinflammatory effects of endotoxin on macrophages may upset lung homeostasis while metals-induced cytotoxicity/necrosis may set up inflammation independent of macrophage-derived cytokines.

Associations between lung function and estimated average exposure to NO2 in eight areas of Switzerland. The SAPALDIA Team. Swiss Study of Air Pollution and Lung Diseases in Adults.

In this paper, we present results from the SAPALDIA study (Swiss Study on Air Pollution and Lung Diseases in Adults) regarding associations between lung function [forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1)], as assessed during the cross-sectional study in 1991, and average levels of NO2 exposure within the eight study communities. We distinguished average home outdoor exposure and average personal exposure to NO2 and obtained exposure estimates by computing regional averages of passive sampler measurements performed by a random subsample of SAPALDIA participants in 1993. Previous analyses had revealed associations between average lung function and average air pollution levels between communities. The present results show that such associations may also be seen within communities: a 10-micrograms per m3 increase in average home outdoor and personal exposure to NO2 between zones of residence of the same community was associated with a change in average FVC by -0.59% [95% confidence limits (CL) = 0.01, -1.19] and -0.74% (95% CL = -0.07, -1.41), respectively. These values, however, are smaller than the ones found for the corresponding associations between study communities: -1.67% (95% CL = -1.01, -2.33) and -2.93% (95% CL = -2.11, -3.75), respectively. The different magnitudes of these two types of associations might be explained by differences in spatial variation between various components of air pollution.

Personal exposure to nitrogen dioxide in Switzerland. SAPALDIA team. Swiss Study on Air Pollution and Lung Diseases in Adults.

Home indoor and outdoor levels, and personal exposures to NO2 were determined for more than 500 subjects in a subpopulation of SAPALDIA by using passive samplers. The overall personal NO2 average was found to be 27 micrograms m-3, the overall indoor average 21 micrograms m-3 and the overall outdoor average 31 micrograms m-3. Personal NO2 levels ranged between the outdoor and indoor levels, with the exception of study areas with low NO2 concentrations. In the winter, the indoor/outdoor ratios were lower than in the summer. Outdoor NO2 levels were higher in winter. In some study areas, indoor NO2 levels were lower in the winter than in the summer due to reduced ventilation but this was not consistent. Personal NO2 concentrations were very similar during all seasons. Gas-cooking and smoking were important factors for elevated indoor and personal NO2 levels (contribution: 5 micrograms m-3, 2 micrograms m-3, respectively). Personal exposure to NO2 correlated best with the indoor NO2 concentrations.

[Swiss Study on Air Pollution and Lung Diseases in Adults (SAPALDIA)]. / Etude suisse sur la pollution de l'air et les maladies respiratoires chez l'adulte (SAPALDIA). Swiss Study on Air Pollution and Lung Diseases in Adults.

Long-term health effects of moderate ambient air pollution are rarely investigated. In Switzerland, no large-scale study has addressed this issue so far. Important results of the Swiss Study on Air Pollution and Lung Disease in Adults (SAPALDIA) are presented. During the period 1991-1993, SAPALDIA investigated a random population sample (18-60 years) in eight Swiss areas with different environmental characteristics (Aarau, Basel, Davos, Geneva, Lugano, Montana, Payerne, Wald). In total, 9651 adults (60%) participated in the cross-sectional investigation (part 1, 1991), consisting of the following standardized procedures: questionnaire (interview), forced expiratory lung function test, bronchial challenge with methacholine, atopy assessment (Phadiatop, unspecific total IgE), allergy skin tests, and endexpiratory CO-measurements. Subjects with a history of respiratory symptoms, increased bronchial reactivity, reduced lung function (FEV1/FVC < 80% predicted) and 150 healthy never-smokers were included in the subsequent diary study (part 2; n = 3281, 1992/93). Peak flow (morning and evening), symptoms, medication, personal activity and visits to the doctor were monitored. Across regions, annual mean values ranged from 9 to 52 mg/m3 (NO2) and 10 to 33 mg/m3 (PM10) respectively. Air pollution had effects on prevalence of dyspnea (+41% per 10 mg/m3 increment of the annual mean PM10, 95% CI 20-65%), on symptoms of chronic bronchitis (+31%, 10-55%), on FVC (-3.1%; -3.7 to -2.6%), and FEV1 (-1.1%; -1.7% to -0.5%), on the incidence of respiratory symptoms and the length of symptomfree intervals (11% change per 10 mg/m3 PM10), but not on the prevalence of asthma. Environmental tobacco smoke (ETS) showed impact on wheezing (OR 1.94; 1.39-2.70), asthma (1.39; 1.04-1.86), bronchitis (1.60; 1.24-2.08) and chronic bronchitis (1.50; 1.11-2.02). Health effects of moderate air pollution were confirmed in Switzerland. Although for the individual the relative risks are small, the public health impact may be considerable. An ongoing follow-up will investigate the mortality profile of the SAPALDIA cohort.

Lung function and long term exposure to air pollutants in Switzerland. Study on Air Pollution and Lung Diseases in Adults (SAPALDIA) Team.

The effect of long-term exposure to air pollutants was studied in a cross-sectional population-based sample of adults (aged 18 to 60 yr; n = 9,651) residing in eight different areas in Switzerland. Standardized medical examination included questionnaire data, lung function tests, skin-prick testing, and end-expiratory CO concentration. The impact of annual means of air pollutants on FVC and FEV1 was tested (controlling for age and age squared, sex, height, weight, educational level, nationality, and workplace exposure). Analyses were done separately for healthy never-smokers, ex-smokers (controlling for pack-yr), for current smokers (controlling for cigarettes per day and pack-yr smoked), and for the whole population. Significant and consistent effects on FVC and FEV1 were found for NO2, SO2, and particulate matter < 10 microm (PM10) in all subgroups and in the total population, with PM10 showing the most consistent effect of a 3.4% change in FVC per 10 microg/m3. Results for ozone were less consistent. Atopy did not influence this relationship. The limited number of study areas and high intercorrelation between the pollutants make it difficult to assess the effect of one single pollutant. Our conclusion is that air pollution from fossil fuel combustion, which is the main source of air pollution with SO2, NO2, and PM10 in Switzerland, is associated with decrements in lung function parameters in this study.

SAPALDIA: methods and participation in the cross-sectional part of the Swiss Study on Air Pollution and Lung Diseases in Adults.

SAPALDIA--the Swiss Study on Air Pollution and Lung Diseases in Adults--focuses on the long term health effects of low to moderate levels of air pollutants as typically seen in different parts of Switzerland. The aim of the SAPALDIA cross-sectional study carried out in 1991 was to determine the prevalence of bronchial asthma, chronic bronchitis and allergic conditions in the adult population of Switzerland and to identify and to determine the respective importance of potentially influencing factors. These could be both personal (smoking habits, allergy status, family history, occupation) and environmental (outdoor and indoor pollution, aeroallergens, climate). A further aim of the cross-sectional study consisted in the identification of individuals susceptible to present symptoms during a two year observation period and to be included in the SAPALDIA follow-up study. This technical report represents the methodological documentation for the cross-sectional study of SAPALDIA. The instruments and the methods of standardisation are presented and discussed. The medical examination consisted of a computerised interview using a standardised questionnaire, the taking of a blood sample for serological tests, allergy skin testing, the measurement of end expiratory CO and body height, and pulmonary function testing followed by methacholine challenge testing or bronchodilatation testing. The pattern of participation and the 9651 participants of the study, representing 59.3% of the sample, are described. Based on information on non-participants gained by telephone interviews and mailed short questionnaires, possible selection biases are quantified and discussed.

Particulate matter less than 10 microns (PM10) and fine particles less than 2.5 microns (PM2.5): relationships between indoor, outdoor and personal concentrations.

Among 17 homes in Switzerland, the relationship between indoor and outdoor levels for particulate matter less than 10 microns (PM10), particulate matter less than 2.5 microns (PM2.5) and NO2 was investigated. In 10 homes, the inhabitants also participated in conducting personal measurements. All homes were naturally ventilated. In homes without any indoor sources and where human activity was low, PM10 I/O ratios amounted to approximately 0.7. Of the indoor sources, smoking had the highest influence on I/O ratios (> 1.8). In homes not containing any apparent source, 'human activity' was an important factor accounting for high indoor levels. However, this factor is difficult to quantify. Personal exposure was in most cases higher than the indoor and the corresponding home outdoor levels. For NO2, gas-cooking was found to have the strongest influence on elevated I/O ratios (> 1.2) whilst for other homes, the I/O ratio was less than 1.

Direct determination of allergens in ambient aerosols: methodological aspects.

In Switzerland the birch tree (Betula verrucosa) major allergen Bet v 1 and the grass (Phleum pratense) pollen major allergen Phl p 5 are of particular relevance for inducing pollinosis. In this study, the protein and major allergen contents of aerosols of different aerodynamic diameters were determined. The aerosols were sampled by Andersen-Impactors and submitted to protein assays and allergen assays (ELISA) specific for Bet v 1 and Phl p 5. The total protein, Bet v 1 and Phl p 5 concentrations were correlated with the corresponding pollen counts. The presence of Bet v 1 in smaller aerosol fractions was demonstrated before and after birch pollen was counted, especially in the lower particle size ranges.