IAQ AND ENVIRONMENTAL HYGIENE ANALYSIS IN SUBDIVIDED UNITS IN HONG KONG

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1 Topic B9: IAQ in rapidly urbanizing cities IAQ AND ENVIRONMENTAL HYGIENE ANALYSIS IN SUBDIVIDED UNITS IN HONG KONG Ka Man LAI 1*, Maggie CHAN 1, KK MA 1, Irene LI 1, Karen LEE 1, Tommy LO 2, and William YU 2 1 Department of Biology, Hong Kong Baptist University, Hong Kong SAR, China 2 World Green Organisation, Hong Kong SAR, China * Corresponding laikaman@hkbu.edu.hk Keywords: Subdivided units, Urban poor, IAQ, Bio-contaminants, Environmental hygiene SUMMARY Purpose: To collect data on indoor air quality (IAQ) and environmental hygiene in subdivided units (SDUs). Methodologies: Forty-one questionnaires and environmental assessments were conducted from July to September Twenty of them were spot checked with IAQ parameters. Airborne microbial diversity was analysed. Allergens, endotoxins and glucans in settled dusts were measured in 8 SDUs. Results: Questionnaire results indicated IAQ and hygiene problems. Temperature and relative humidity were the worst performed IAQ parameters, while most SDUs reached Good Class in CO, total VOCs and PM 10 levels. Some units had high microbial counts and endotoxin and glucan levels, and showed regional microbial disparity. Discussion: Biological pollution is a concern in SDUs and linked to building, occupant and environmental factors. Conclusions: This study gives some insights into the conditions of SDUs and the unique research needs in this environment. INTRODUCTION Housing is a big problem in Hong Kong according to the Long Term Housing Strategy Consultation Document (Transport and Housing Bureau, 2013). Housing issues not only can hit the urban poor harder, in this community housing issues can also lead to many other social, health and economic issues. Reviewing data from different surveys (Policy 21 Ltd., 2013; Platform of concerning subdivided units and issue in Hong Kong, 2013), they estimated that about 35,000 to 280,000 low-income households are living in subdivided units (SDUs). Subdivided units is defined as individual living quarters having been subdivided into two or more smaller units for rental (Policy 21 Ltd., 2013). These units are generally perceived to have poor environmental conditions. In addition, according to the surveys, people living in SDUs are worried about their health. However, no measurement has ever been taken to determine how poor the SDU environment is, which leads to widespread concern of the environmental condition and health. What is the main hazard and health risk faced by the occupants living in SDUs? Housing and health are strongly linked together in many different ways (WHO, 2010). Some environmental and hygiene factors such as bad smell, frequent sighting of pest and mis- and no management of waste around the living area are perceived as health threats. Environmental allergens from cockroaches, rodents and dust mites, endotoxins and glucans are common agents found in deprived areas in inner cities, which are associated with asthma, irritation and other respiratory illnesses in children and other susceptible individuals. Dampness and mould contamination is a recognised risk factor for poor health.

2 Children living near busy roads and industrial and waste disposal areas may expose to high levels of PM and toxic agents. Poor ventilation and maintenance of air conditioning systems may worsen the IAQ and provide a breeding ground for microbial growth. The transmission of Tuberculosis, Legionnaires' disease and severe acute respiratory syndrome (SARS) are some of the examples, which have close links with the building structure and quality. The rising report of fleas and pathogen vectors in Hong Kong is also an important environmental health concern. Other hazards, which can impact indoor health, include volatile organic compounds, tobacco smokes, carbon monoxide and radon. Identification of major environmental hazards is an important task because some of the hazards are building and environment related and difficult to be fixed in the SDUs, while others are linked to the occupant activities, building management and knowledge of indoor health, which may be able to remediate through education and simple support. The IAQ Management Group of HKSAR Government (2003) issued a set of guideline in 2003 to assess IAQ in offices and public places but not in residential buildings let alone SDUs. Some studies have measured IAQ in conventional residential homes in Hong Kong, and allergens and endotoxins were measured in a few studies such as in asthmatic children s homes (Leung et al. 2010; Lee et al. 1999; Lee et al. 2002). We believe that it is an important study to investigate the IAQ and hygiene in SDUs because there are no data available about this environment, and these are real issues faced by people living there. It is a critical time in Hong Kong to collect these data because SDUs are an important social issue as well. It is a big debate on the kind of role and policy the government should take and develop. The finding of this study can illustrate environmental quality and remediation measures in SDUs. METHODOLOGIES Questionnaires, IAQ and environmental assessment, and microbial identification A random sampling was adopted to survey the general information and living conditions of SDU tenants identified as low-income households by social workers from July to September Indoor and outdoor air samples were simultaneously taken following the standard methods (IAQ Management Group, 2003). Parameters measured included: temperature (temp), relative humidity (RH), air velocity, carbon dioxide (CO 2 ), carbon monoxide (CO), total volatile organic compounds (total VOCs), respirable particulate matter (PM 10 ) and airborne bacteria and fungi. Bacteria were examined according to their morphological differences on agar plates and under the microscope, and also by gram-stain. The most abundant types of bacteria were further identified to the genus level by sequencing the 16S rrna gene on MiSeq System (Illumina, USA). Fungi were identified to the genus level based on the fruiting body and spore. Dust collection, extraction and analysis in eight SDUs Floor and bed dusts were collected in accordance with ISACC phase II protocol (Weiland et al., 2004) and extracted for detection of endotoxins, allergens (Der p1, Bla g1, Bla g2, Rat n1 and Asp f1) and (1 3)-β-D-glucans (Schram et al., 2005). SDUs were selected based on (i) high counts of indoor bacteria, and/or (ii) poor hygiene impression by our researchers. Statistical analysis

3 Biological parameters were correlated with the building, occupant and environmental factors using Spearman's rank correlation. Microbial diversity data were fourth root transformed and statistically analysed using Analysis of Similarities (ANOSIM) to determine the diversity difference between indoor or outdoor air and districts. RESULTS AND DISCUSSION Questionnaire results on buildings, occupants, IAQ and hygiene information Environmental quality and hygiene conditions are poor in the SDUs. 24.4% respondents use shared washrooms. The average living area per capita is 41.4 ft 2, compared with the minimum living area of 59.2 ft 2 according to the Hong Kong Housing Authority 1. About 10% SDUs have no window installed in their units. Ventilation louvers to the corridors are blocked in some units, and exhaust fans in toilets are broken or not in regular use. For the units with windows installed, the environments outside are mainly traffic roads, back alleys and wet markets. 56% respondents complain about poor ventilation. In general, the buildings (all > 30 years old) are low-rise in the city and located mainly in the deprived areas. For public hygiene, 59% respondents consider it as poor; 39% feel disgusting smell around the area. Garbage collection points are always located at the corner of stairs, a typical feature of old buildings, and garbage bins are usually uncovered. In terms of pest infestation, 75.6% respondents have found mosquitos in their units, while 48.8% usually get mosquito bites, particularly during rainy seasons. 14.6% respondents reported flea infestation, and about 12.2% reported fleabites among members of household, most of them are children. 85.4% respondents have cockroaches in the units and the common area in the building. Besides, 48.8% have seen rats in their units, which is unusual in Hong Kong. 43.9% SDUs have mould contamination during humid seasons, i.e. March to May. 51.2% have water seepage during rainy days. Among the SDUs with mould, 77.7% also have water seepage problems. In terms of the self-reported health condition, 39.0% reported sickness in the past 6 months. Most of them suffered from cold, fever and cough. 19.5% respondents indicate that they have respiratory symptoms and illness, but not necessarily related to moving into the unit. The cleaning practice of the households was also investigated. About 65.8%, 46.3% and 48.8% of households clean their living space, kitchen and washroom, respectively at least once per day. 90.2% of the units are equipped with air conditioners, in which 45.9% of those households clean the dust filters irregularly, and 13.5% never clean the filter. IAQ of the 20 units Temperature and relative humidity were the worst performed IAQ parameters, while most units reached Good Class in CO, total VOCs and PM 10 levels (Table 1). Table 1. IAQ measured compared to HKIAQ guidelines (IAQ Management Group, 2003) Parameters Range % SDUs met (Good Class) or above Temp 22.7 to % (< 25.5 ) RH 58 to 93 % 30% (< 70 %) Air movement 0 and 2.15 m/s 45% (< 0.3 m/s) 1 Hong Kong Housing Authority, Housing in Figures 2013 indicates that only 0.4% households with living space per person below 5.5m 2.

4 CO levels 0 to 2 ppmv 100% (< 8.7 ppmv) CO 2 levels 471 and 1600 ppmv 40% (< 1000 ppmv) PM 10 levels and 0.9 mg/m 3 80% a (< 0.18 mg/m 3 ) Total VOCs 0 µg/m 3, except one 3749 µg/m 3 95% (< 600 µg/m 3 ) Total bacterial counts 133 to > 6535 CFU/m 3 63% b ( < 1000 CFU/m 3 ) Total fungal counts 50 to 695 CFU/m 3 N/A a % calculated from 15 SDUs; b % calculated from 19 SDUs Outdoor environments affected the indoor temp and RH. High indoor temperature is one of the key problems faced by the occupants. We suspected that indoor RH would be higher than the outdoor because of poor ventilation and other occupant activities, which generate moisture indoors, such as cooking and hanging washed clothes. However, only one unit showed an obvious indoor and outdoor difference (18%), and the indoor RH reached 90% in this unit. One unit had a particularly high indoor air movement (2.15 m/s, outdoor 0.5 m/s) because of ceiling fan operating during visit. It is likely that this indoor air movement drove outdoor air into the unit, and the outdoor air contributed to the high indoor PM 10 and bacterial counts in this unit. Outdoor CO 2 levels were high in some units (30% > 600 ppmv outdoors), which may mislead the ventilation quality of indoor air. The high outdoor CO 2 may reflect busy traffic and close proximity to building exhausts and other sources of CO 2. One unit had a very high PM 10 (0.9 mg/m 3, air movement 2.15 m/s), which also had a high outdoor PM 10 (0.8 mg/m 3 ). This may indicate a significant outdoor contribution to the indoor air and a high level of air mixing in this unit. Outside this unit was a nylon shade roof covered with rubbish and clutter. This unit also had a high indoor and outdoor microbial count (>2614 CFU/m 3 ). The indoor total VOCs in one unit was extremely high (3749 µg/m 3 ) compared to no detection outdoors. No source of VOCs was recorded but this unit was above a wood-crafting workshop. Two previous studies revealed that 100% and >85% of the conventional flats had indoor bacterial counts below 1000 CFU/m 3 (compared to 67% in SDUs), and the flat exceeded this level had bacterial counts not more than an average of 1500 CFU/m 3 (compared to 6 out of 7 SDUs exceeded the Good Class had above 1500 CFU/m 3 ) (Lee et al., 1999 and 2003). This implies that not only more SDUs have poor biological air quality, the level of pollution is also higher. In Lee et al. (2003) study, the source of the indoor air pollution was from outdoors. In our study, only 3 out of the 7 problematic units were directly associated with outdoor source, and the rests were linked to indoor contamination. This supports that SDUs has a role in degrading the IAQ. Fungal counts were low, although fungal I/O ratio could go up to 3.84 times indicating indoor fungal sources. Microbial diversity Most microbial studies ended in total counts. It is an opportunity missed to inform the nature and source of bacterial contamination. Therefore, microbes were identified (Figure 1 and 2). In total 81 Gram +ve, 115 Gram ve, 6 Gram stain unidentified, 1 unidentified in subculture and 1 not a bacterium were identified. The top three most abundant and frequently identified bacteria indoors and outdoors were all Gram +ve bacteria in the genus of Micrococcus and Staphylococcus. These bacteria are mainly originated from humans and commonly found indoors. It is assumed that Gram +ve bacteria with hardy cell walls are more persistent than Gram -ve bacteria. 27 fungal species were isolated from the units and the outside environments among the genus Alternaria, Aspergillus, Aureobasidium, Bipolaris, Chaertomium, Curvularia, Mucor, Pythium, Rhizopus, Schizophyllum, and Ulocladium. The most abundant and frequently identified fungi in the indoor and outdoor samples are Alternaria, Aspergillus and Rhizopus. Some of the species within these genera are medically

5 important, allergenic (e.g. Alternaria alternate, Aspergillus fumigatus, A. flavus, A. niger) and pathogenic (e.g. Aspergillosis). Figure 1. Bacterial diversity in indoor and outdoor air samples in the 20 SDUs Figure 2. Fungal diversity in indoor and outdoor air samples in the 20 SDUs

6 Correlating microbial parameters with environmental, building and occupant factors can help understanding the source, nature and impact of the airborne microbes (Table 2). For example, total indoor bacteria were associated with indoor CO 2 level (Occupant/Environmental factors) and outdoor bacteria (environmental factors). The number of bacterial types indoors was associated with the number of occupants and kids living in the SDUs. Total indoor fungal level was not associated with any factor, while the level of individual fungi was associated with the building factors. Table 2: Biological parameters correlate with environmental, building and occupant factors Biological parameters Significantly correlated with/inversely correlated with r coefficient Total bacteria In Occupant/Env CO 2 conc. In.480 * Environment Total bacteria Out.576 ** Total bacteria Out No sig. No sig. No sig. Bacteria I/O Environment CO 2 conc. In.551 * CO conc. In.529 * Indoor G+ve/G-ve Environment PM 10 In * PM 10 Out * Outdoor G+ve/G-ve Building Ceiling height.653 ** Occupant/Env CO 2 conc. In.581 ** Indoor bacterial types Number of occupants.620 ** Occupant Number of kids under age * Number of people at sampling.488 * Occupant/Env CO 2 conc. In.481 * Outdoor bacterial types Number of occupants.495 * Occupant Average daily hr at home * Total fungi In No sig. No sig. No sig. Total fungi Out Environment Temperature Out * RH Out.455 * Fungi I/O No sig. No sig. No sig. Alternaria In Building Building age yrs.703 ** Aspergillus In Building Number of unit in flat ** Rhizopus In Building Number of unit in flat ** Average hygiene score # * **Correlation is significant at the 0.01 level (2-tailed); *Correlation is significant at the 0.05 level (2-tailed); # Hygiene score given by our researchers (from 1 to 10; 1: Clean, 5: Acceptable, 10: Very Dirty) Microbial diversity was compared between indoor and outdoor samples and districts. Indoor and outdoor bacterial samples were significantly different. Outdoor bacterial diversity in Mong Kok (MK) was distinctive and significantly different from Tsuen Wan (TW), Kwai Chung (KC) and Kung Tong (KT). KT was different from KC. Indoor bacterial diversity was significantly different between TW and MK, and also between TW and KC. Fungal diversity between indoor and outdoor samples and districts (Figure 3) was significantly different. This clear distinction between districts is out of our expectation, and implies regional factors contributing to biological air quality. In this pilot study, the data were inadequate to determine whether or not living in a particular region will be exposed to a higher level of fungal allergens because this will require a more detailed analysis of the allergenicity of the species but this result supports the public health value for further studies in this area.

7 Figure 3. Comparison of fungal diversity in different districts Level of allergens, endotoxins and glucans in eight units The poor IAQ and hygiene conditions reported in the questionnaire and the high levels of microbes in some units strongly supported that biological pollution is a concern in SDUs. A wide range of biological pollutants may be present in this environment (Table 2). Table 2. Level of indoor and outdoor microbes, endotoxins and glucans Locations Indoor bacteria (CFU/m 3 ) Bacteria In/Out Indoor fungi (CFU/m 3 ) Fungi In/Out Endotoxin floor/bed conc. (EU/g) Endotoxin floor/bed load (EU/m 2 ) Glucan floor/bed conc. (ug/g) Glucan floor/bed load (ug/m 2 ) TW01 > / / / / 0.74 TW02 > / / / / 0.80 TW / / 2280 >41.36/ >6.58/ 3.79 MK01 > / / / / 1.49 MK / / 104 >65.27/ >9.58/ 1.51 MK07 > / / / / 0.19 KC01 > Floor Floor 2373 Floor Floor 6.39 KC / / / / 0.34 In general, floor dust levels were low at homes with children, which may relate to the regular cleaning practice and furnishing. No household used carpet or sofa, and the bedding areas were tidy up for use in the daytime. 7 units had at least one of the endotoxin measurements above the median value in the conventional homes with asthmatic children in Hong Kong (bed: EU/g, 497 EU/m 2 ; floor: EU/g, 248 EU/m 2 ) (Leung et al. 2010). In Leung

8 et al. s study, they found that the mattress endotoxin levels were associated with increasing frequency of wheezing episodes (11300 EU/g associated with 1-3 attacks, and EU/g with > 12 attacks). This implies that 2 SDUs (TW02 and TW04) with > EU/g can trigger > 12 wheezing attacks if asthmatic children live in the units. MK07 is going to be demolished and at very poor condition. The high bacterial and fungal counts and the highest endotoxin concentration and load in floor dusts may indicate serious water damage in the building. Half of the units had glucans in bed dusts above the geometric mean of 25.2 µg/g reported in a study in Taiwan; levels as low as ug/m 2 were associated with increasing peak flow variability in symptomatic children (Wu et al. 2009). Most respondents reported cockroaches, rats and mould in their units. However, no SDUs had detectable allergens except in MK01, 3.62 U/g of Bla g1 exceeding the sensitization level (Tranter, 2005). In Leung et al. (2010), dust mite allergens were detected at >58% homes, while they were undetectable in our samples. This may be due to the use of bed space during the day. CONCLUSIONS This pilot study gives some insights into the conditions of SDUs and the unique research needs in this environment. Biological pollution is a concern in SDUs but more studies are needed to investigate seasonal effects, sources, impacts and remediation of this pollution. REFERENCES Indoor Air Quality Management Group (2003) A guide on indoor air quality certification scheme for offices and public places. The Government of the Hong Kong Special Administrative Region. Lee SC, Li WM, Ao CH (2002) Investigation of indoor air quality at residential homes in Hong Kong case study. Atmospheric Environment, 36 (2), Lee SC, Chang M, Chan KY (1999) Indoor and outdoor air quality investigation at six residential buildings in Hong Kong. Environment International, 25 (4), Leung TF, Wong YS, Chan IHS et al (2010) Indoor determinants of endotoxin and dust mite exposures in Hong Kong homes with asthmatic children. Int Arch Allergy Immunol, 152, Platform of concerning subdivided units and issue in Hong Kong (2013) 全港劏房居民狀况調查. Policy 21 Ltd. (2013) Survey on subdivided units in Hong Kong, Transport and Housing Bureau, The Government of the Hong Kong Special Administrative Region. Schram D, Doekes G, Boeve M et al (2005) Bacterial and fungal components in house dust of farm children, rudolf steiner school children and reference children the PARSIFAL study. Allergy, 60 (5), Transport and Housing Bureau (2013) Long Term Housing Strategy Consultation Document, The Government of the Hong Kong Special Administrative Region. Tranter D (2005) Indoor allergens in settled school dust: A review of findings and significant factors. Clinical & Experimental Allergy, 35 (2), Weiland S, Björkstén B, Brunekreef B et al (2004) Phase II of the international study of asthma and allergies in childhood (ISAAC II): Rationale and methods. European Respiratory Journal, 24 (3), Wu FF, Siebers R, Chang CF et al (2009) Indoor allergens and microbial bio-contaminants in homes of asthmatic children in central Taiwan. J Asthma., 46 (7),