Indoor and Built Environment

The Hong Kong Environmental Protection Department has recently launched a set of guidance notes on indoor air quality (IAQ) management for offices and public places. An IAQ Certification Programme will be con ducted on a self-regulatory basis that is intended to divide IAQ in mechanically ventilated buildings into three classes. Due to the large number of buildings in Hong Kong and the associated cost implications, a sim plified, operationally feasible and scientifically sound as sessment has been developed. Twenty-five government buildings covering eight different types of premises were examined in a trial-run programme to verify the validity of the proposed methodology. Among these 25 prem ises, only 1 (4%) achieved level 1 while 11 (44%) achieved the level 2 objective. The remaining 13 prem ises (52%) met the level 3 objective. High concentrations of volatile organic compounds and carbon dioxide were found to be the dominating parameters that made a building unable to meet class level 2. This measurement study has also illustrated the very different nature of IAQ found in different types of buildings where the pattern of air conditioning operation and indoor air pollutant sources can influence it substantially.

Analyses are described estimating the extent to which confounding by dietary variables and education might bias the reported association of smoking by the husband with lung cancer risk in non-smoking women. For each of the four variables fruit, vegetable and dietary fat con sumption and education, independent estimates of their relationships with lung cancer risk in non-smokers were combined by meta-analysis. The risks were estimated as 0.83 per standard deviation [SD, 95% confidence interval (CI) = 0.74-0.93, based on n = 9 studies] for fruit con sumption, as 0.84 per SD (Cl = 0.75-0.93, n = 11) for vege table consumption, as 1.17 per SD (Cl = 1.08-1.26, n = 7) for dietary fat consumption and as 0.92 per year (Cl = 0.89-0.96, n = 17) for education. For each of the same four variables independent estimates of the difference between non-smokers exposed or unexposed to envi ronmental tobacco smoke at home were also combined. Using unweighted means, the differences were esti mated as -0.1752 SDs for fruit, -0.0460 SDs for vegeta bles, +0.1750 SDs for dietary fat and -0.5174 years for education (n = 11, 17, 14 and 15). Using weighted means the differences were -0.0986 SDs for fruit, -0.0387 SDs for vegetables, -0.0464 SDs for dietary fat and -0.1023 for education. The weighted estimates are dominated by one very large study whose results, particularly for dietary fat and education, differed from those seen in the other studies. Using these data and methodology devel oped to account for confounding by multiple correlated variables, simultaneous adjustment for fruit, vegetables, dietary fat and education is estimated to reduce the increase in lung cancer risk associated with each 10 ciga rettes/day smoked by the husband from 10% (95% Cl 5- 15%) to 6% (1-11%) using unweighted means or to 9% (5-14%) using weighted means. Uncertainties in the esti mation procedure are discussed. Other sources of bias will be considered in later papers in this series.

An airborne fungal spore survey in five indoor environ ments in Santiniketan, West Bengal, India was carried out for a period of 2 years using the Astir 1-day personal volumetric sampler as well as a Rotorod sampler and sedimentation plates. A total of 24 fungal spore genera in addition to Aspergilli were recorded of which three were Phycomycetes (Cunninghamella, Rhizopus, Syncepha lastrum), two were Ascomycetes (Chaetomium, Pleospo ra), one was Basidiomycete (Ganoderma ) and the re mainder were fungi imperfecti. Aspergillus contributed most to the total aerospora in the environment, followed by Curvularia and Cladosporium. The occurrence of aerospora exhibited a distinct seasonal periodicity in their annual distribution, perhaps due to differences in meteorological conditions. Concentrations were lowest in summer and highest during monsoon and postmon soon periods. High concentration of spores in winter was due to a large number of saprophytic forms, of which Cladosporium was the major component. The predomi nance of Aspergillus, Curvularia, Cladosporium, Alter naria in all the indoor environments contributed to their ability to grow in various substrata. Moreover, indoor aeroflora might have been diluted by the outside aeroflo ra entering through different inlets. The clinical investi gation clearly demonstrated the highly allergenic nature of the ten tested fungal antigens that may be due to a higher prevalence of such fungal forms in the surround ings of those tested.

Standards for final clearance after lead abatement have been established for child-related facilities and public housing in the United States. For these existing stan dards final clearance for lead is based on surface load ing. However, no standards have been suggested for buildings that are identified as not child-related or public housing (e.g. commercial buildings). Calculations have now been made to determine a proposed final clearance loading value for buildings or structures that are not child-related or public housing and for the two situations: lead-free and non-lead-free. The values proposed for floors are 1,100 μg Pb.ft^-2 for lead-free buildings and 1,000 μg Pb.ft^-2 for non-lead-free buildings. Blood lead levels in adults should not increase after exposure at or below these suggested lead-loading values.

This paper presents a Chinese approach to ventilation and air conditioning, which are important measures needed to improve the indoor air environment of a build ing. They are important because improper design of a system may degrade the indoor air environment rather than enhance it. This is a situation that might be called sick air conditioning. Also, in circumstances where the outside air is heavily polluted air treatment is necessary to avoid worsening the indoor environment. This paper seeks to highlight the way in which improperly designed ventilation and air conditioning systems may be im proved by use of purified air produced by filtration and other means and through avoidance of the build-up of microbial flora.