scholarly journals Normal background levels of air and surface mould reserve in English residential building stock: a preliminary study towards benchmarks based on NAHA measurements

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Yasemin Didem Aktas ◽  
Morten Reeslev ◽  
Héctor Altamirano ◽  
Neil May ◽  
Dina F. D’Ayala
Keyword(s):  
Indoor Environment ◽  
Surface Cleaning ◽  
National Standards ◽  
Mould Growth ◽  
Building Stock ◽  
Local Climate ◽  
Background Levels ◽  
Water Damage ◽  
Normal Background ◽  
Indoor Mould

This paper reports results obtained from a surface (both visually clean and dirty/dusty surfaces) and active (aggressive or activated) air testing scheme on 140 residential rooms in England, without visible water damage or mould growth, along with a few rooms with visible mould growth/water damage tested for comparison purposes. The aim was to establish normal background levels of mould in non-water-damaged interiors to benchmark a ‘normal’ indoor environment, and in turn when there is a need for further investigation, and, possibly, remediation. Air and surface mould was quantified based on the activity of β-N-acetylhexosaminidase (EC 3.2.1.52; NAHA). The obtained readings showed a log-normal distribution. Ninety-eight percent of the samples obtained from visually clean surfaces were equal to or less than 25 relative fluorescence units (RFU), which is suggested to be the higher bound for the range which can be used as a success criterion for surface cleaning/remediation. Of samples obtained from visually dirty/dusty surfaces, around 98% were below 450 RFU, which is suggested to define the lower-bound for abnormally high levels of mould, rare even on dirty/dusty surfaces. Similarly, around 98% of the air samples were found to have 1700 RFU or below. Values above 1700 RFU are therefore deemed unlikely in a non-problem indoor environment and can be indicative of a possible problem inducing mould growth. The samples with values below 1700 were further divided into three proposed sub-categories. Finally, the obtained RFU values and the suggested benchmarks were compared to those obtained from 17 non-residential indoor environments tested previously in Copenhagen, and the benchmarks that are currently used in Danish national standards, and they were both found to be highly congruent, suggesting that local climate regimes and room functions might not be as influential on indoor mould levels as commonly thought, or that the nuances between England and Denmark in terms of these factors are not strong enough to lead to sizable changes in the typical indoor mould levels in these countries’ building stocks.

scholarly journals Normal background levels of air and surface mould reserve in English residential building stock: A preliminary study towards benchmarks based on NAHA measurements

2020 ◽  
Author(s):  
Yasemin Didem Aktas ◽  
Yasemin Didem Aktas ◽  
Yasemin Didem Aktas ◽  
Yasemin Didem Aktas ◽  
Yasemin Didem Aktas ◽  
...  
Keyword(s):  
Indoor Environment ◽  
Surface Cleaning ◽  
National Standards ◽  
Mould Growth ◽  
Building Stock ◽  
Local Climate ◽  
Background Levels ◽  
Water Damage ◽  
Normal Background ◽  
Indoor Mould

This paper reports results obtained from a surface (both visually clean and dirty/dusty surfaces) and active (aggressive or activated) air testing scheme on 140 residential rooms in England, without visible water damage or mould growth, along with a few rooms with visible mould growth/water damage tested for comparison purposes. The aim is to establish normal background levels of mould in non-water-damaged interiors to benchmark a normal indoor environment, and in turn when there is a need for further investigation, and, possibly, remediation. Air and surface mould was quantified based on the activity of β-N-acetylhexosaminidase (EC 3.2.1.52; NAHA). The obtained readings showed a log-normal distribution. 98% of the samples obtained from visually clean surfaces were equal to or less than 25 relative fluorescence units (RFU), which is suggested to be the higher bound for the range which can be used as a success criterion for surface cleaning/remediation in non-problem buildings. Of samples obtained from visually dirty/dusty surfaces, around 98% were below 450 RFU, which is suggested to define the lower-bound for abnormally high levels of mould, rare even on dirty/dusty surfaces. Similarly, around 98% of the air samples were found to have 1700 RFU or below. Values above 1700 RFU are therefore deemed unlikely in a non-problem indoor environment and can be indicative of a possible problem inducing mould growth. The samples with values below 1700 were further divided into three proposed sub-categories. Finally, the obtained RFU values and the suggested benchmarks were compared to those obtained from 17 non-residential indoor environments in Copenhagen tested previously, and the benchmarks that are currently used in Danish national standards, and they were both found to be highly congruent, suggesting that local climate regimes and room functions might not be as influential on indoor mould levels as commonly thought, or that the nuances between England and Denmark in terms of these factors are not strong enough to lead to sizable changes in the typical indoor mould levels in these countries.

scholarly journals Normal background levels of air and surface mould reserve in UK residential building stock

2019 ◽  
Author(s):  
Yasemin Didem Aktas ◽  
Morten Reeslev ◽  
Hector Altamirano ◽  
Neil May ◽  
Dina D'Ayala
Keyword(s):  
Indoor Environment ◽  
Residential Building ◽  
Surface Cleaning ◽  
National Standards ◽  
Mould Growth ◽  
Building Stock ◽  
Local Climate ◽  
Background Levels ◽  
Water Damage ◽  
Indoor Mould

This paper reports results obtained from a surface (both visually clean and dirty/dusty surfaces) and active (aggressive) air testing scheme on 140 residential rooms in England, without visible water damage or mould growth, along with a few rooms with visible mould growth/water damage tested for comparison purposes, with the aim of providing background levels of mould in non-water-damaged interiors to benchmark a normal indoor environment, and in turn when there is a need for further investigation, and, possibly, remediation. Air and surface mould was quantified based on the activity of β-N-acetylhexosaminidase (EC 3.2.1.52; NAHA). The obtained readings showed a log-normal distribution. 98% of the samples obtained from visually clean surfaces were equal to or less than 25 relative fluorescence units (RFU), which is suggested to be the higher bound for the range which can be used as a success criterion for surface cleaning/remediation in non-problem buildings. Of samples obtained from visually dirty/dusty surfaces, around 98% were below 450 RFU, which is suggested to define the lower-bound for abnormally high levels of mould, rare even on dirty/dusty surfaces. Similarly, around 98% of the air samples were found to have 1700 RFU or below. Values above 1700 RFU are therefore unlikely in a non-problem indoor environment and can be indicative of a possible problem inducing mould growth. The samples with values below 1700 were further divided into three proposed sub-categories. Finally, these values were compared to those obtained in Denmark in a similar study and are currently used in national standards, and they were found highly congruent, suggesting that local climate regimes and room functions might not be as influential on indoor mould levels, or that the nuances between UK and Denmark in terms of these factors are not strong enough to lead to sizable changes in the typical indoor mould levels in these countries.

scholarly journals Generation and Characterization of Indoor Fungal Aerosols for Inhalation Studies

2016 ◽  
Vol 82 (8) ◽  
pp. 2479-2493 ◽  
Author(s):  
Anne Mette Madsen ◽  
Søren T. Larsen ◽  
Ismo K. Koponen ◽  
Kirsten I. Kling ◽  
Afnan Barooni ◽  
...  
Keyword(s):  
Species Composition ◽  
Indoor Environment ◽  
Building Materials ◽  
Inhalation Exposure ◽  
Single Species ◽  
Fungal Species ◽  
Exposure Level ◽  
Exposure System ◽  
Content Type ◽  
Water Damage

ABSTRACTIn the indoor environment, people are exposed to several fungal species. Evident dampness is associated with increased respiratory symptoms. To examine the immune responses associated with fungal exposure, mice are often exposed to a single species grown on an agar medium. The aim of this study was to develop an inhalation exposure system to be able to examine responses in mice exposed to mixed fungal species aerosolized from fungus-infested building materials. Indoor airborne fungi were sampled and cultivated on gypsum boards. Aerosols were characterized and compared with aerosols in homes. Aerosols containing 107CFU of fungi/m3air were generated repeatedly from fungus-infested gypsum boards in a mouse exposure chamber. Aerosols containedAspergillus nidulans,Aspergillus niger,Aspergillus ustus,Aspergillus versicolor,Chaetomium globosum,Cladosporiumherbarum,Penicillium brevicompactum,Penicillium camemberti,Penicillium chrysogenum,Penicillium commune,Penicillium glabrum,Penicillium olsonii,Penicillium rugulosum,Stachybotrys chartarum, andWallemia sebi. They were all among the most abundant airborne species identified in 28 homes. Nine species from gypsum boards and 11 species in the homes are associated with water damage. Most fungi were present as single spores, but chains and clusters of different species and fragments were also present. The variation in exposure level during the 60 min of aerosol generation was similar to the variation measured in homes. Through aerosolization of fungi from the indoor environment, cultured on gypsum boards, it was possible to generate realistic aerosols in terms of species composition, concentration, and particle sizes. The inhalation-exposure system can be used to study responses to indoor fungi associated with water damage and the importance of fungal species composition.

scholarly journals Exposure to Indoor Mouldy Odour Increases the Risk of Asthma in Older Adults Living in Social Housing

2019 ◽  
Vol 16 (14) ◽  
pp. 2600 ◽  
Author(s):  
Loveth Moses ◽  
Karyn Morrissey ◽  
Richard A. Sharpe ◽  
Tim Taylor
Keyword(s):  
Older Adults ◽  
Older People ◽  
Asset Management ◽  
Social Housing ◽  
Western World ◽  
Mould Growth ◽  
Building Type ◽  
Indoor Mould ◽  
Mould Contamination

Background: Indoor dampness is thought to affect around 16% of European homes. It is generally accepted that increased exposure to indoor dampness and mould contamination (e.g., spores and hyphae) increases the risk of developing and/or exacerbating asthma. Around 30% of people in the Western world have an allergic disease (e.g., allergy, wheeze and asthma). The role of indoor mould contamination in the risk of allergic diseases in older adults is yet to be fully explored. This is of interest because older people spend more time indoors, as well as facing health issues due to the ageing process, and may be at greater risk of developing and/or exacerbating asthma as a result of indoor dampness. Methods: Face-to-face questionnaires were carried out with 302 participants residing in social housing properties located in South West England. Self-reported demographic, mould contamination (i.e., presence of mould growth and mouldy odour) and health information was linked with the asset management records (e.g., building type, age and levels of maintenance). Multivariate logistic regression was used to calculate the odd ratios and confidence intervals of developing and/or exacerbating asthma, wheeze and allergy with exposure to reported indoor mould contamination. We adjusted for a range of factors that may affect asthma outcomes, which include age, sex, current smoking, presence of pets, education, and building type and age. To assess the role of mould contamination in older adults, we compared younger adults to those aged over 50 years. Results: Doctor-diagnosed adult asthma was reported by 26% of respondents, 34% had current wheeze while 18% had allergies. Asthma was common among subjects exposed to reported visible mould (32%) and reported mouldy odour (42%). Exposure to visible mould growth and mouldy odour were risk factors for asthma, but not for wheeze or allergy. Exposure to mouldy odour increased the risk of asthma in adults over the age of 50 years (odds ratio (OR) 2.4, 95% confidence interval (CI) 1.10–5.34) and the risk was higher for females than for males (OR 3.5, 95% CI 1.37–9.08). These associations were modified by a range of built environment characteristics. Conclusions: We found that older adults living in social (public) housing properties, specifically women, may be at higher risk of asthma when exposed to mouldy odour, which has a number of implications for policy makers and practitioners working in the health and housing sector. Additional measures should be put in place to protect older people living in social housing against indoor damp and mould contamination.

scholarly journals Parametric study on the hygrothermal performance of timber frame walls with external airtightness membranes in a temperate maritime climate

2019 ◽  
Vol 282 ◽  
pp. 02080
Author(s):  
Valentina Marincioni ◽  
Federico Lorenzetti ◽  
Hector Altamirano-Medina
Keyword(s):  
Parametric Study ◽  
Indoor Environment ◽  
Moisture Transfer ◽  
Wall Structure ◽  
Two Dimensional ◽  
Mould Growth ◽  
Timber Frame ◽  
Maritime Climate ◽  
Hygrothermal Performance ◽  
Control Layer

In recent years, external airtightness membranes have become an option for timber frame wall systems, as they allow high levels of air- and wind-tightness with an easy installation and provide rainwater protection during construction. This opens up the option of removing the internal air and vapour control layer. However, the hygrothermal risks associated to this option could be higher than in conventional construction, because vapour transfer can occur from the indoor environment into the timber frame wall not just via diffusion but also advection. This can lead to moisture accumulation and mould growth risk within the wall structure. This paper presents a parametric study that aims at identifying the moisture risk when external airtightness membranes are installed on a timber frame wall in a temperate maritime climate. The parametric study considered the two-dimensional heat, air and moisture transfer within a timber frame wall. Parameters having higher influence on moisture risk were identified and should be considered when designing robust wall systems.

Mycotoxins in water-damaged and mouldy wheat from temporary bulk stores in Queensland

1986 ◽  
Vol 37 (6) ◽  
pp. 561 ◽  
Author(s):  
BJ Blaney
Keyword(s):  
Ochratoxin A ◽  
Aspergillus Flavus ◽  
Aflatoxin Production ◽  
Wheat Crop ◽  
Mould Growth ◽  
Australian Wheat ◽  
Water Damage ◽  
Growing Region

Temporary bulk stores are used by the Australian wheat industry to cope with peak wheat deliveries. Such stores are vulnerable to water damage if the plastic covering sheets are damaged, and extensive mould growth may then result. Samples of mouldy grain from stores in the main wheat-growing region of southern Queensland were assayed for aflatoxins B1, B2, G1, and G2, ochratoxin A and sterigmatocystin, but only aflatoxins B1 and B2 were detected. Of 152 mouldy samples from 12 temporary stores of the 1981 wheat crop, anatoxins were detected in 21 (range 0.002-0.060, mean 0.016 mg B1 kg-1). Aflatoxins were also present in 10 out of 13 samples from the single store of the smaller 1982 crop (range 0.003-0.500, mean 0.064 mg B1 kg-1). Aflatoxins were detected at trace levels (0.003-0.004 mg B1, kg-1) in 2 out of 70 samples of apparently clean, free-flowing grain from rhese same stores. Both the frequency of contamination and aflatoxins concentrations were low, indicating either that the inoculum of Aspergillus flavus was low or that conditions were unsuitable for aflatoxin production.

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