Lars Gunnarsen

Adaptation to indoor air pollution

Abstract The change in the perception of polluted air was studied during the first 15 min of exposure in climate chambers. Subjects, 16 female and 16 male, ages 18–30 y, served as air quality judges during 42 exposures. They were exposed to different concentrations of human bioeffluents (500–4000 μL/L CO 2 ), tobacco smoke (0.25–2.5 μL/L CO), and emissions from building materials (−). The subjects voted every 2 min on scales for odor intensity and acceptability of the air quality, while they were exposed to constant levels of the air pollution. Perception of bioeffluents reached a low level independent of concentration after a dew minutes. Adaptation to tobacco smoke caused acceptability to increase, but votes still depended on concentration. Ventilation for comfort may be reduced considerably if a few minutes of discomfort are acceptable or if the occupants are exposed to a gradually increased pollution level during the first 10 min or more of their stay in a space.

Sampling, extraction and measurement of bacteria, endotoxin, fungi and inflammatory potential of settling indoor dust

Selection of sampling device, sampling location and period are important first steps in the measurement of exposure to bioaerosols in indoor air. The steps following the sampling include treatment of samples and laboratory analysis. In this study, settling bacteria, endotoxin, fungi and serine protease have been measured in Danish homes using Electrostatic Dust Fall Collectors (EDCs). The effects of the presence of occupants, sampling on open surfaces versus in bookcases and treatment of samples have been studied. Concentrations of bacteria and endotoxin were significantly higher when occupants were at home than when they were absent. Across homes, higher concentrations of fungi were found in spring than in winter, as was the total inflammatory potential, while higher concentrations of protease were found in winter than in spring. The placement of the EDCs in bookcases versus on an open surface significantly affected the measured concentrations of bacteria and endotoxin. Direct extraction of EDC cloths caused a higher measured concentration of bacteria, fungi and serine protease than if EDC cloths were extracted post-storage at -20 °C. Extraction of EDC cloths caused an average of 51% and 58% extraction of bacteria and fungi respectively. In conclusion, EDCs should be placed on open surfaces during the sampling, how much occupants are present in their home during sampling and sampling season should be considered, EDC cloths should not be stored in a freezer before extraction of microorganisms, but extraction suspensions can be stored at -80 °C without affecting the number of microorganisms significantly.

Polychlorinated biphenyls (PCBs) in indoor air originating from sealants in contaminated and uncontaminated apartments within the same housing estate

Twenty-four congeners of polychlorinated biphenyls (PCBs) were measured in 83 air samples and 20 elastic sealants samples of apartments with PCB-containing sealants. In addition, PCBs were measured in 21 air samples from reference apartments located in an uncontaminated section of the same estate. The PCB(tot) levels in the air of the contaminated section were 168-3843 ng m(-3) (mean: 1030 ng m(-3)), while the mean levels in the reference apartments were 6.03 ng m(-3). The sum of the 24 measured PCB congeners in sealants from the contaminated section was 187-221680 mg kg(-1). Principal component analysis revealed four groups among the sealant samples with different congener compositions, only two of which were clearly similar to known PCB mixtures, while two were not. Significant correlations and intercorrelations were observed between the lower chlorinated congeners in air and sealant, e.g. for PCB 28(air) and 28(seal) (p=0.04) and for PCB 28(air) and 52(air), 52(seal). However, no correlation was observed between the lower chlorinated congeners and the sums of PCB (∑PCB(6) or ∑PCB(24)) or the higher chlorinated congeners. Analysis of air concentrations in relation to questionnaire data indicated that the indoor air levels could be reduced by increased cleaning and airing frequencies.

Emission of Isothiazolinones from Water-Based Paints

The isothiazolinone preservatives methylisothiazolinone (MI), methylchloroisothiazolinone (MCI), and benzisothiazolinone (BIT) are used in a wide variety of products including paint and cosmetics, and they are known to cause allergic contact dermatitis. Among painters they are one of the most common causes of contact dermatitis. Furthermore, they are all volatile, and severe reactions caused by emissions of especially MI from paint have been reported recently. In this study the concentrations of MI, BIT, and MCI in water-based paint were analyzed by LC-MS-MS, and the emissions from the paints were measured in climate chambers and in an apartment. Nineteen paints were analyzed for the content of MI, MCI, and BIT. All 19 paints contained MI, 16 contained BIT, and 4 contained MCI. In the chamber experiment emission of MI peaked within hours of application but then continued at a slow rate for more than 42 days. MCI was emitted more slowly and peaked after several days. BIT emissions were all around the limit of detection. In the apartment we were able to detect emission of MI several days after application. Long lasting evaporation and thus chronic exposure give credibility to the clinical observations that MI can be an important cause of airborne contact dermatitis among painters and consumers.

Plasma polychlorinated biphenyls in residents of 91 PCB-contaminated and 108 non-contaminated dwellings-an exposure study.

BACKGROUND In the1950s-1970s polychlorinated biphenyls (PCBs) were used in several countries as plasticizers in elastic sealants in buildings. OBJECTIVE The primary objective was to study whether residents of PCB-contaminated dwellings had higher plasma levels of PCBs than their neighbours in non-contaminated dwellings. The secondary objective was to study possible associations between concentrations of PCBs in the indoor air and in the plasma of residents. METHODS Stratified cross-sectional study of residents of a housing estate with four sections, of which only one section had PCB-containing sealants. The determination of 27 PCB congeners in plasma was performed among 134 exposed and 139 non-exposed residents. Air measurements were conducted in 104 flats. RESULTS Significant differences in plasma PCBs between exposed versus non-exposed were found for most of the lower chlorinated and many of the higher chlorinated congeners. The median of sum of 27 PCBs was approximately four times higher in exposed compared with non-exposed residents. The elevated PCB concentrations persisted in multivariable analyses controlling for relevant cofactors. We found significant correlations between PCB indoor air concentrations and the PCB concentration in the plasma of the residents for ten of the lower chlorinated congeners. CONCLUSION Our study confirms that indoor air exposure to PCBs from PCB containing sealants may result in a considerable internal PCBs exposure of the residents. For the first time we were able to demonstrate that the internal exposure to low chlorinated PCBs is significantly associated with the indoor air concentration of these congeners.

Indoor and outdoor exposure to ultrafine, fine and microbiologically derived particulate matter related to cardiovascular and respiratory effects in a panel of elderly urban citizens.

To explore associations of exposure to ambient and indoor air particulate and bio-aerosol pollutants with cardiovascular and respiratory disease markers, we utilized seven repeated measurements from 48 elderly subjects participating in a 4-week home air filtration study. Microvascular function (MVF), lung function, blood leukocyte counts, monocyte adhesion molecule expression, C-reactive protein, Clara cell protein (CC16) and surfactant protein-D (SPD) were examined in relation to exposure preceding each measurement. Exposure assessment included 48-h urban background monitoring of PM10, PM2.5 and particle number concentration (PNC), weekly measurements of PM2.5 in living- and bedroom, 24-h measurements of indoor PNC three times, and bio-aerosol components in settled dust on a 2-week basis. Statistically significant inverse associations included: MVF with outdoor PNC; granulocyte counts with PM2.5; CD31 expression with dust fungi; SPD with dust endotoxin. Significant positive associations included: MVF with dust bacteria; monocyte expression of CD11 with PM2.5 in the bedroom and dust bacteria and endotoxin, CD31 expression with dust serine protease; serum CC16 with dust NAGase. Multiple comparisons demand cautious interpretation of results, which suggest that outdoor PNC have adverse effects on MVF, and outdoor and indoor PM2.5 and bio-aerosols are associated with markers of inflammation and lung cell integrity.

Occurrence of organochlorine pesticides in indoor dust

Organochlorine pesticides are present in the environment and suspected of causing serious health effects. Diet has been the main exposure source, but indoor source release is gaining focus. Within a monitoring study of polychlorinated biphenyls of Danish buildings built during the 1960s and 1970s, we coincidently determined extreme levels of dichlorodiphenyltrichloroethane (DDT) levels in two of ten random samples. This raises concern and further large scale investigations are warranted to confirm this.

Concentrations of Formaldehyde in new Danish Residential Buildings in Relation to WHO Recommendations and CEN Requirements

It is uncertain if current Danish legislation regarding emission of formaldehyde from wood-based panels could assure that concentrations of formaldehyde in the indoor air of buildings containing the material would meet the World Health Organization (WHO) guideline. This is of particular concern since the recent recognition by International Agency for Research on Cancer that formaldehyde is carcinogenic to humans. Therefore, the purpose of this study was to determine whether residents of newly built Danish residential houses could be exposed to safe levels of formaldehyde. Geometric mean concentration of formaldehyde measured in 20 residential buildings was 0.04 mg m−3. Formaldehyde concentrations in two buildings (10%) exceeded the WHO guideline value. In order to explain the relatively high concentrations, a second phase was performed. The aim was to identify the significant formaldehyde sources and to discuss the source strength in relation to field measurements and WHO guidelines. The results showed wide differences between the materials tested, but all steady-state concentrations were below the European standard requirement for class E1. These measurements formed the basis for model calculations of possible resulting concentrations in residential rooms, suggesting that indoor concentrations above the WHO maximum limit could occur. The calculations applied a worst case scenario with all surfaces covered with materials emitting the maximum permissible amount of formaldehyde show indoor concentrations as high as 0.6 mg m−3.

Variation in residential radon levels in new Danish homes.

Radon-222 gas arises from the radioactive decay of radium-226 and has a half-life of 3.8 days. This gas percolates up through soil into buildings, and if it is not evacuated, there can be much higher exposure levels indoors than outdoors, which is where human exposure occurs. Radon exposure is classified as a human carcinogen, and new Danish homes must be constructed to ensure indoor radon levels below 100 Bq/m(3). Our purpose was to assess how well 200 newly constructed single detached homes perform according to building regulations pertaining to radon and identify the association between indoor radon in these homes and municipality, home age, floor area, floor level, basement, and outer wall and roof construction. Median (5-95 percentile) indoor radon levels were 36.8 (9.0-118) Bq/m(3) , but indoor radon exceeded 100 Bq/m(3) in 14 of these new homes. The investigated variables explained nine percent of the variation in indoor radon levels, and although associations were positive, none of these were statistically significant. In this study, radon levels were generally low, but we found that 14 (7%) of the 200 new homes had indoor radon levels over 100 Bq/m(3). More work is needed to determine the determinants of indoor radon.

Evaluation of building materials individually and in combination using odour threshold

This paper presents results of an experimental procedure to observe the impact of building materials on perceived air quality. An untrained panel of 25 adult subjects perceived the quality of polluted air in small-scale chamber settings. The air pollution was generated by emissions from individual materials, by combinations of these materials and by mixtures of emissions from single materials. The results showed that the exposure response relationship varies for one of the tested materials compared with the others. The study also confirmed that interaction among building materials is often negligible from the perception point of view, which is in contradiction with the findings published in the literature. Further analysis of data indicated that linear addition of olfs of single materials is still a permissible simplified method to estimate the sensory pollution load in the presence of combinations of building materials in the absence of any other practical technique.