Indoor air pollution and its effect on pulmonary function of adult non-smoking women: I. Exposure estimates for nitrogen dioxide and passive smoking.

The potential effects of indoor NO2 and tobacco smoke on the respiratory system were studied using pulmonary function data from a longitudinal study. In 1982, NO2 was measured in 163 homes of non-smoking adult women and detailed information on smoking inside the house was gathered over the period 1965-1982. Personal exposure to NO2 was calculated from the measured levels and the activity pattern of the study population (range 11-139 micrograms NO2/m3). Historical exposure was estimated using regression models of NO2 on house characteristics. It is shown that estimation of historical exposure to indoor NO2 on the basis of house characteristics only is, at present, too inaccurate for use in epidemiological studies. Actual measurement of NO2 is unavoidable for exposure assessment in health effect studies of indoor exposure to NO2.

Contribution of wood stoves and fire places to mutagenic activity of airborne particulate matter inside homes.

Wood combustion produces compounds that are mutagenic in the Salmonella/microsome assay. As combustion products can be emitted in the home and the use of wood as a residential energy source is growing, an impact on human health might be of concern. In this study experiments were carried out to determine the contribution of wood combustion in stoves and fire places to indoor mutagenic activity under normal living conditions. Airborne particles from living rooms which were heated by stoves, or by fire places, and from outdoors were collected simultaneously. In each room two samples were collected during two consecutive weeks: one week the room was heated by central heating, the other week by wood combustion. Sampling took place in a total of 24 homes. Methanol extracts of the samples were tested in the Salmonella/mammalian microsome assay. Results show that mutagenic activity of outdoor air exceeds indoor mutagenicity. At the same time a correlation is found between in- and out-door mutagenicity, both with and without S9. However, a large difference is found between the ratio -S9/+S9 of in- and out-door mutagenic activity. Systematic differences in the ratio -S9/+S9 between control and experimental conditions are not observed. The use of wood stoves caused an increase of indoor mutagenicity in 8 out of 12 homes. It could be concluded that the use of an open fire consistently leads to an increase of mutagenic activity. This increase was caused by wood combustion products.

Indoor air pollution in a Kenyan village.

In April 1986, a study was carried out within rural households in Maragua area, Muranga District, Republic of Kenya, to assess the degree of indoor air pollution and to find its relationship, if any, to acute respiratory infections (ARI) among children aged below 5 years within the study. This study was carried out within an ongoing aetiological and epidemiological community study on ARI as a collaborative effort between the Department of Paediatrics, University of Nairobi; the Department of Chemistry, Kenyatta University; the Department of Environmental Sciences, Agricultural University, Wagenigen, The Netherlands; the World Health Organization; and the Ministry of Health, Republic of Kenya. Repeated 24 hour measurements of respirable suspended particles (RSP) and nitrogen dioxide (NO2), were carried out in 36 randomly selected houses where most of the cooking was done on open fires using firewood and crop residues as fuel. Data on house characteristics and activity in the study were gathered by questionnaire. The mean of 24 hour average RSP concentration (1400mg/m3), average during the 7 hours of daily burning (3000-4000mg/m3), and evening peak levels (up to 3600mg/m3) indicate that deleterious health effects due to exposure to excessive levels of toxic pollutants in smoke from biomass combustion are likely to occur especially among pre-school children and women. Concentrations of selected polycyclic hydrocarbons in the particulate material were found to be high. It was not possible to demonstrate a relationship between the indoor air pollution and episodes of ARI partly because of small sample size and also the more or less homogeneous nature of pollution among all the households.

Long-term average suspended particulate concentrations in smokers' homes.

Suspended particulate matter (SPM) concentrations were measured in about 100 homes in the city of Arnhem, The Netherlands. Most homes were sampled for 2 months continuously. Monthly average SPM concentrations ranged from 20-570 micrograms/m3. From 26 houses, smoking data were gathered at a later date. A clear relationship was found between SPM concentrations and number of smokers in the home.

Agreement between qualitative exposure estimates and quantitative exposure measurements.

A method for qualitative estimation of the exposure at task level was used and validated with actual measurements in five small factories. The results showed that occupational hygienists were in general the most successful estimators. Plant supervisors and workers handled the estimation method less successfully because of more misclassification of the tasks. The method resulted, in general, in a classification of tasks in four exposure categories ranging from no exposure to high exposure. The exposure categories correlated positively with mean concentrations, but showed overlapping exposure distributions. This resulted in misclassification of the exposure for individual workers when a relatively large interindividual variability in exposure levels within an exposure category was present. The results show that this method can be used for workplace exposure zoning, but that the usefulness of the estimates for epidemiological purposes is not clear-cut and depends strongly on the actual exposure characteristics within a workplace. A combination of the qualitative exposure estimation method together with assessment of the exposure levels by measurements makes a rearrangement of tasks or individual workers possible and could improve the validity of this method for epidemiological purposes.

Enumeration of viable fungi in occupational environments: a comparison of samplers and media.

The performance of sampling for fungi using four widely used microbiological air sampling devices and three broad spectrum media was compared in seven occupational settings. Total colony forming units counts ranged from 10 to 3700 CFU/m3. The sampling efficiencies of the Andersen N-6 sampler, slit sampler, and Reuter centrifugal air sampler (RCS) were comparable, whereas the SAS sampler underestimated CFU counts by approximately 50%. The correlation between the RCS results and the other three samplers used was lower compared to their mutual correlations. There were no large differences in performance of the three media tested: malt extract agar, dichloran glycerol (18) agar, and dichloran rose bengal chloramphenicol agar. Coefficients of variation of duplicate samples were large compared to commonly used methods for sampling dust and chemicals. It is concluded that the N-6 and slit sampler perform best, although RCS is useful in probes because it is easy to handle. The three media tested yielded similar results. Further testing of DG-18 is recommended, as it inhibits fast growing genera and, thus, counting colonies is easier.

Empirical modelling of chemical exposure in the rubber-manufacturing industry.

As part of a study of working conditions chemical exposure was assessed in 10 rubber-manufacturing plants in The Netherlands. Personal exposures to airborne particulates, rubber fumes and solvents, and also dermal contamination, were measured. To identify factors affecting exposure the personal exposure levels and information on tasks performed, ventilation characteristics and production variables were used in multiple linear regression models. The exposure was generally very variable. The specific circumstances in each department of each plant determined the actual levels of exposure to a large extent. The factors affecting exposure turned out to be different for each of the types of exposure considered. The model for exposure to airborne particulates explained 40% of the total variability and incorporating the actual time spent on a task only slightly improved the model (R2 = 0.42). The handling of chemicals in powder form was the main factor affecting exposure, forced ventilation having a negligible effect. The model for exposure to curing fumes (measured as the cyclohexane-soluble fraction of the particulate matter) explained 50% of the variability. Both curing temperature and pressure determined the level of rubber fumes. Local exhaust ventilation showed a significant exposure reducing effect. The effect of curing different elastomers was not statistically significant. Dermal exposure to cyclohexane-soluble matter could only be explained to a limited extent (R2 = 0.22). Tasks with frequent contact with (warm) compound and maintenance tasks in the engineering services departments resulted in high dermal exposure. Tasks in which solvents were directly used explained 56% of the variation in solvent exposures. Exposure data, together with information on tasks, methods of work, ventilation and production throughout a branch of industry, can be used to derive empirical statistical models which occupational hygienists can apply to study factors affecting exposure. These determining factors are of crucial importance, whenever hazard control or epidemiological research is the ultimate goal.

Indoor nitrogen dioxide exposure and children's pulmonary function.

Elevated concentrations of nitrogen dioxide (NO2) are produced in the home by the use of unvented gas appliances. In studies on potential health effects of indoor exposure to NO2, exposure has mostly been estimated from the presence or absence of sources like gas cookers in the home. This leads to misclassification of exposure, as NO2 concentrations in the home depend also on source use, ventilation habits, time budgets, etc. The availability of cheap, passive monitoring devices has made it possible to measure indoor concentrations of NO2 directly in health effects studies, albeit with averaging times of one to several days. So far, it has not been evaluated whether this increases the sensitivity of a study to detect health effects of NO2. In this paper, a comparison is made between NO2 sources and weekly average indoor NO2 measurements, as predictors of pulmonary function in a study among children aged 6-12 years. The relationship between exposure and lung functions was found to be generally non-significant in this study. The results further suggested that in this study, measuring indoor NO2 concentrations with passive monitors offered no advantage over the simple use of source presence as exposure variable.

Relationship of airborne endotoxin and bacteria levels in pig farms with the lung function and respiratory symptoms of farmers.

Previous studies have demonstrated a high prevalence of respiratory and other symptoms and a decrement in lung function among pig farm workers, although the relationships with specific agents present in the work environment remain obscure. This study was therefore undertaken to investigate the relationship between symptoms, lung function and airborne endotoxin, ammonia and dust levels in piggeries. Information on symptoms, lung function, endotoxin, ammonia and dust levels was available for 183 pig farmers who worked in 136 farms. For 62 farms information was present on the levels of bacteria and gram-negative bacteria. For these 62 farms, endotoxin exposure measurements were taken in more than one stable. In general, no significant correlations were found between lung function and chronic respiratory symptoms, or dust and ammonia levels. The endotoxin concentration in stables was negatively related to most lung function variables, but only for the subgroup of 62 farmers was a statistically significant relationship found between endoxtoxin exposure and FEV1. A borderline statistically significant and negative relationship was found between the endotoxin concentration and the FVC. Symptoms experienced during or shortly after work showed odds ratios larger than one with the levels of bacteria, gram-negative bacteria and endotoxin, indicating a positive relationship. No consistency in the relationship between symptoms and dust levels was found. The results suggest that endotoxins and (gram-negative) bacteria probably play an important role in the development of symptoms and lung function changes among pig farmers.

Indoor NO2 pollution and personal exposure to NO2 in two areas with different outdoor NO 2 pollution.

Indoor NO2 concentrations were measured in the kitchen, the living room and bedroom of 612 houses in two different areas in the Netherlands. In a group of housewives living in these homes, personal exposure to NO2 was measured. NO2 concentrations indoors were dependent on the presence or absence of (un)vented gas appliances. Personal NO2 exposure was only different between the two areas in the group with the lowest indoor concentrations. In this study, it was determined that gas appliances inside the house are the most important factor with respect to NO2 exposure and that outside NO2 concentration played a secondary role, except in situations where gas appliances were absent.

Wood-dust exposure during wood-working processes.

Personal and ambient full shift concentrations of inhalable wood dust were measured at different wood-working processes in two joineries and a furniture factory in The Netherlands. The current occupational exposure limit for wood dust is still 5 mg m-3 total dust, but the Dutch Expert Committee for Occupational Standards has recently recommended a health-based limit of 0.2 mg m-3 (total wood dust). The main purpose of the present study was to characterize current wood-dust exposures during different wood-working activities in order to determine whether compliance with the proposed limit was feasible. The wood-dust exposures in the joineries were usually much lower than 5 mg m-3, but in the furniture factory the present limit was regularly exceeded. Sanding, especially hand sanding, nearly always resulted in exposures above 5 mg m-3. Almost all personal exposures were higher than the proposed health-based limit of 0.2 mg m-3 and therefore can be considered to generate a health risk to the workers. The measurements performed may help in setting priorities and will serve as a basis for the development of a control strategy to reduce the average exposure.

Airway hyper-responsiveness and the prevalence of work-related symptoms in workers exposed to irritants.

The association between exposure to airway irritants and the presence of work-related symptoms and whether this association was modified by airway hyper-responsiveness, smoking, and allergy by history was studied in 668 workers of synthetic fiber plants. A Dutch version of the British Medical Research Council (BMRC) questionnaire with additional questions on allergy and work-related symptoms was used to assess symptoms, and a standardized histamine challenge test of airway hyper-responsiveness (AHR) was employed. Work-related symptoms were defined as having more than usual eye and respiratory symptoms during work. On the basis of job titles and working department, the exposure status of all workers was characterized into seven groups: (1) reference group; (2) white collars; (3) SO2, HCl, SO4(2-); (4) polyester vapor; (5) oil mist and oil vapor; (6) polyamide and polyester vapor; and (7) multiple exposure. The association between exposure groups and work-related symptom prevalence was estimated by means of multiple logistic regression. The overall prevalence of the work-related symptoms were: cough 9%; phlegm 6%; dyspnea 7%; wheeze 2%; eye symptoms 16%; nasal symptoms 15%. Exposure to airway irritants was significantly associated with work-related symptoms, independent of AHR, smoking, allergy by history, and chronic respiratory symptoms. The association of exposure group with work-related symptoms was stronger for subjects with AHR than for subjects with no AHR. The association with dyspnea and/or wheeze was also stronger for smokers than for nonsmokers and ex-smokers. In contrast, the association between exposure and a higher prevalence of work-related symptoms was stronger in subjects with no history of allergy than in subjects with history of allergy. This is most likely due to the relatively high prevalence of background symptoms in (nonexposed) allergic subjects. It is concluded that exposure to irritants in the working environment might lead to respiratory symptoms, even if exposure levels are relatively low.

Respiratory symptoms in damp homes. A pilot study.

The association between living in damp homes and the prevalence of health symptoms was investigated in a population of 519 occupants (adults and children) of 185 homes. Positive associations were found between the reporting of respiratory and some other health symptoms and living in a damp home. The concentration of variable mould spores in indoor air was measured, using modified Andersen samplers, in the living rooms of a sample of 36 homes. The results were compared with the occurrence of dampness characteristics in their homes as reported by the occupants. Homes with at least two dampness characteristics showed higher average spore counts and higher prevalence of respiratory symptoms.

Indoor air pollution in developing countries and acute respiratory infection in children.

PIP: Indoor air pollution emerges as an important risk factor for acute respiratory infections (ARI) in developing countries. In many developing countries, in addition to an increasing amount of tobacco smoke, many homes contain high levels of smoke from the combustion of biofuels such as wood, crop residues, and animal dung for cooking or heating. In about half the world's households, such fuels are used for cooking daily, usually without a flue or chimney and with poor ventilation. Results of investigations in 6 developing nations have shown the range of indoor pollution in such circumstances. The best single indicator for comparison of toxic noncarcinogenic effects is most likely respirable particulates, similar to tar reported for cigarette emissions. Results of studies in animals suggest any difference in respiratory-system toxicity according to mass is not likely to be large. On the basis of the small amount of evidence available, peak and daily exposures to indoor particulate levels in villages in developing countries seem to be about 20 times greater than in developed nations. The results of a semi-quantitative epidemiological study conducted in Nepal showed a direct relation between reported hours/day spent near the stove by infants and children aged under 2 years and episodes of life threatening acute respiratory infections. If one discounts the many possible confounding factors, extrapolation shows that by moving all children into the lowest smoke exposure groups as much as 25% of moderate and severe infections would be eliminated. Extrapolation from studies of both ARI and environmental tobacco smoke also indicates indirectly the potential effect of indoor smoke from biofuels. Some environmental tobacco smoke studies have reported a dose-response relation between the number of cigarettes smoked in the home and respiratory symptoms in children. In sum, biofuel smoke is likely to be a factor in ARI, but its importance in relation to other risk factors is difficult to establish. It may be that prevention of acute respiratory infections could be best realized by initially addressing other risk factors or by addressing smoke solely in the context of broad based programs for several risk factors.^ieng

Self reported symptoms and inhibition of acetylcholinesterase activity among Kenyan agricultural workers.

OBJECTIVES: This study was part of the East African pesticides project. The general objective was to assess health hazards posed by handling, storage, and use of pesticides, on agricultural estates and small farms with a view to developing strategies for prevention and control of pesticide poisoning. The aim of this paper is to describe the prevalence of symptoms in this population, to relate levels of inhibition to reported symptoms and evaluate at which levels of inhibition symptoms become increased. METHODS: Complete data were available for 256 exposed subjects and 152 controls from four regions in Kenya. A structured questionnaire on symptoms experienced at the time of interview was given to all subjects and controls. Information was also obtained on sex, age, main occupation, and level of education. Symptoms reported during the high exposure period, were initially clustered in broader symptom categories from reference literature on health effects of pesticides that inhibit cholinesterase (organophosphate and carbamate). Prevalence ratios were estimated for symptoms with changes in cholinesterase activity in serum. RESULTS: Symptom prevalence in exposed subjects was higher during the high exposure period than the low exposure period, although these differences were not significant. Interestingly, a clear and significant change in symptoms prevalence was found in the controls with a higher prevalence in the low exposure period. Analysis of the relation between cholinesterase inhibition and symptoms showed that prevalence ratios were significantly > 1 for respiratory, eye, and central nervous system symptoms for workers with > 30% inhibition. Similar results were found for analyses with the actual level of acetylcholinesterase activity. CONCLUSION: The results suggest the presence of a relation between exposure and acetylcholinesterase inhibition, acetylcholinesterase activity, and respiratory, eye, and central nervous system symptoms. Increased symptom prevalence was found at acetylcholinesterase activities generally considered to be non-adverse.

Exposure to dust, endotoxins, and fungi in the animal feed industry.

In the Dutch animal feed industry, approximately 6000 workers are exposed to organic dust, originating mainly from raw materials such as grain, pulses (peas and beans), and waste products from the vegetable oil and starch industries. In this study, 79 stationary dust samples and 530 personal dust samples from eight animal feed production facilities were analyzed. The stationary total dust samples showed gravimetric concentrations ranging from 0.2 to 25 mg/m3 (geometric mean [GM] 1.3 mg/m3). Concentrations of smaller particle fractions (respirable, thoracic, and inspirable dust) were considerably lower. Personal inspirable dust concentrations were considerably higher than stationary concentrations and were strongly related to job titles. Pooled personal inspirable dust concentrations ranged from 0.2 to 450 mg/m3 (GM = 2.4 mg/m3). After adjusting for differences between inspirable and total dust, 25% of the measurements exceeded the Dutch maximum allowed concentration (MAC) for total nuisance dust (10 mg/m3) and 42% exceeded the American Conference of Governmental Industrial Hygienists' threshold limit value for grain dust (4 mg/m3). Endotoxin concentrations ranged from 0.2 to 1870 ng/m3 inspirable dust (GM = 5.1 ng/m3). Endotoxin appeared to be less prevalent in respirable dust than in larger dust fractions. Concentrations in dust appeared to be related to stages in the production process. Colony-forming units (cfu) of fungi ranged from 130 to 15,300 cfu/m3 (GM = 2300 cfu/m3) and were in parallel measurements more strongly related to endotoxin concentrations than to dust concentrations. Clearly, workers in the Dutch animal feed industry are frequently exposed to dust levels above recommended Dutch and American levels. Exposure levels to endotoxin and to fungi are quantified.(ABSTRACT TRUNCATED AT 250 WORDS)

Indoor air pollution by carbon monoxide and nitrogen oxides.

The results of an exploratory survey of indoor levels of carbon monoxide and nitrogen dioxide from gas-fired cooking and waterheating appliances in the Dutch cities of Arnhem and Enschede in the fall of 1980 are reported. Measurements were carried out electrochemically (Ecolyzer 2000) or with Draeger tubes in the case of CO and with Palmes diffusion tubes (5 to 8 days exposure) in the case of NO2. For CO, in 18% (27%) of the homes visited the limit of 600 (300) ppm in the flue gases was exceeded, whereas the Dutch Installation Code Standard of 50 ppm CO in room air was exceeded in 17% of the homes. The arithmetic mean value of the NO2 concentration in 286 homes was 118 micrograms/m3 with a range of 35 to 472 micrograms/m3. The corresponding figures for living rooms were 58 and 35 to 346 micrograms/m3, respectively. Outdoor NO2 concentrations were 2 to 3 times lower than indoor concentrations.

Biological monitoring of acrylonitrile exposure.

A study was made of the excretion pattern of acrylonitrile (AN) in urine of 15 AN-exposed workers. During a 7-day working period with the following 2 days off, the workers delivered all their urines separately. Exposure data, collected by personal monitoring, showed a mean 8-hour TWA value of 0.13 ppm. The excretion of AN in urine (AN(U) ) showed a typical pattern; concentrations peaked at the end or shortly after the end of the workday and decreased rapidly until the beginning of the next workday. A control group of 41 nonexposed workers of the same company showed a significant increase of AN(U) with increasing number of cigarettes smoked. The AN(U) concentrations of the exposed workers however were, despite the low exposure, much higher than those of the controls, both during the workdays and during the days off. Biological monitoring of AN-exposed workers by assessing AN(U) therefore seems a very sensitive exposure evaluation method, especially because it accounts for inhalation as well as skin penetration as routes for entering the body.