Indoor and Built Environment

Smoke inhalation remains a major cause of morbidity and mortality. Clinical and laboratory studies have re vealed numerous potentially toxic components of com bustion in the fire environment and in human tissue samples. However, the frequency and importance of the various compounds remains poorly understood. A new simple method to quantitatively measure volatile or ganic compounds (VOCs) in small samples of the blood of fire victims has been developed utilising the 'purge and trap' method of gas phase chromatography with flame ionisation detection using two columns. Thirty- three compounds were identified on the basis of the retention index method with acceptable repeatability and reproducibility. This method should permit a more complete investigation of the toxic volatile organic com pounds found in fire victims.

The provision of underground parking facilities (UPFs) has become a necessity particularly in densely popu lated urban areas and business districts. Indoor air quali ty (IAQ) in such facilities is of great concern due to vehi cle-induced emissions. This paper presents an IAQ as sessment at six representative UPFs in Beirut using car bon monoxide and volatile organic compounds as IAQ indicators. For this purpose, concentrations of both pol lutants were measured at different time intervals throughout the day. Vehicular emission factors (EFs) were estimated using the EMFAC7F1.1 model. A tran sient mass balance model was then applied to construct concentration profiles. The ventilation rates required to maintain pollutant concentrations within acceptable standards were estimated under maximum UPF occu pancy, and a sensitivity analysis was conducted to evalu ate the effect of changes in EMFAC7F1.1 input parame ters on EFs and ventilation rates.

This study was motivated by a need to establish criteria for evaluating observations of moisture damage with respect to exposure and adverse health effects. The data base used included information on moisture damage from 164 dwellings and questionnaire data collected from the occupants. Moisture damage observations were classified according to eleven variables characteris ing damage by, for example, size, duration and type of damaged material. Five health symptom scores were devised based on the questionnaire data. Visible mould associated with respiratory infections, irritative and skin symptoms. Damage <1 m ² in size was associated with general and skin symptoms, and >4 m2 in size associated with respiratory infections and skin symptoms. Damage of <3 years duration was associated with respiratory infections and damage that had existed for 3-10 years was associated with general, irritative and skin symp toms. Symptom scores were associated more frequently with damage to organic rather than inorganic materials. Criteria used to evaluate the association between the classification of moisture damage and symptom scores were excess risk compared to a two-category classifica tion, dose responsiveness, and biological plausibility of the findings. Despite the complexity of interpretation, the results show that more accurate models of moisture damage with respect to exposure and adverse health effects can be established.

The present study is one of the first attempting to assess the problem of indoor air pollution in an urban village of the Indian capital, Delhi. Indoor air sampling was carried out for the period of Jan-May 1999, using an 8-stage cas cade impactor (Anderson sampler), at a constant flow rate of 1 CFM (28.31 I.min^-1), with an impactor pre-sepa rator which cuts off particles larger than 10 μm in aerody namic diameter. Glass fibre filter papers were used for all sampling. Cascade impactor samples were digested in two fractions of PM₁₀ viz. coarse (>2.1 μm) and fine (<2.1 μm). Total PM₁₀ concentration, both coarse and fine, was measured. The samples collected were ana lysed for trace metals by atomic absorption spectrome try (AAS), using a model Philips PU-9200X. A consider able amount of the PM₁₀ (both coarse and fine fractions) was found to be heavy metals, in addition the anions SO^2- ₄, NO ^- ₃ were found in the indoor environment regard less of the level of indoor activity. Analyses of sulphate (SO^2- ₄) and nitrate (NO^- ₃) were carried out using a Hitachi U-2000 UV-VIS spectrophotometer.

Results from pre- and postconstruction radon measure ments in a new housing development are presented. The houses were built in an area that had not been previously associated with elevated indoor radon concentrations. Exhalation measurements of gravel and stone from the site and soil gas measurements under several houses did not indicate an elevated radon potential. However, 4 of 21 finished houses (or 19%) exhibited annual average indoor radon concentrations over 200 Bq.m^-3 (5.4 pCi/l). The highest concentrations were observed in the first house built and in 1 of the 6 houses built differently than the original designs, with the elements of a subfloor ven tilation system included for possible radon control if nec essary. These results suggest that site investigations can be of limited value in determining where notto include radon protection measures in new housing. Also, that care must be taken to adequately inform everyone in volved in the building process ofthe importance of main taining a tight seal against the ground to prevent possi ble radon gas entry into a house.

The Acarex test is an easy, rapid and cost-effective means of assessing exposure to house dust mites. The present study was designed to evaluate the correlation between the Acarex test using a 4-point and a 7-point scale and the major allergens content (Der p1 + Der f1 ) of house dust samples measured by an ELISA technique and also to assess the validity of the test with regard to both sampling and reading of the colour scale. Some 719 house dust samples from patients' homes were evaluat ed using the supplied 4-point scale (classes 0, 1, 2, 3) and again with interpolation of 3 intermediate scale points (classes 0.5, 1.5, 2.5) and Der p1 + Der f1 content using ELISA. Reliability of sampling was studied in 39 dwell ings comparing results obtained by householders and technicians. Reproducibility of reading the colorimetric scale was evaluated in 3 trained technicians and 15 untrained people. The correlation between the Acarex and the ELISA results was 0.68 (p < 0.0001) with class 0 reliable for assessing low allergen levels, class 1 unable to discriminate, and classes 2 and 3 reflecting high aller gen levels (class 3 identified 94.2% of samples with an allergen content greater than 10 μg.g^-1). Discrepancies between Acarex scores for samples collected by patients and those collected by technicians did not exceed half a scale point. Reproducibility of reading by trained techni cians gave intraindividual and interindividual coeffi cients of variation of 0% for classes 0 and 3 and about 20% or more for the other classes. On average readings by untrained participants had 42% discrepancies, mostly in classes 1 and 2. We conclude that the Acarex test is a useful home test whether used by patients or techni cians ; misclassifications of colour readings were less fre quent at the scale extremes. Copyright©2001 S. KargerAG, Basel

This letter was shown to the author, Dr. Peter Dingle, who agrees with the points raised. He makes the observation that the analysis of results is a difficult problem, but one that should be tackled remember ing what needs to be done to understand the problem rather than what can be done. However, it is always better to be too thor ough than too simplistic.