Ensuring Good Indoor Air Quality in Buildings Ensuring Good Indoor Air Quality in Buildings 3

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Buildings in urban areas are exposed to pollutants from outdoor Introduction sources, such as road traffic, boiler flues and other combustion plants, industrial processes and construction activities – so good According to the latest UN data, 54.5% of the world’s ventilation is essential. In the past ventilation has depended on population was living in urban settlements in 2016, with air permeability through cracks and gaps in the building fabric, 23%, or 1.7 billion, living in cities with at least a million combined with air bricks, windows and mechanical ventilation. inhabitants. That percentage is estimated to rise to 60% This does not necessarily improve indoor air quality and can result by 2030. In the same period the number of cities with 10 in excessive energy consumption. The modern approach is to ‘build million inhabitants is expected to rise from 31 to 41. With tight, ventilate right’. This means making buildings airtight and the growth in urbanisation comes the risk of increased air installing ventilation systems that reduce the ingress of outdoor Table of contents pollutants, while preventing the build up of indoor pollutants. pollution, which the World Health Organization estimates is the cause of three million deaths globally each year. This publication summarises the issues that building owners, While outdoor air pollution can impact the quality of indoor architects, designers and facilities managers face when seeking to air in buildings, an array of other factors also negatively provide good indoor air quality. It gives an overview of the sources affect indoor environments and the health of occupants. and types of pollutants likely to affect different indoor environments Introduction 3 This is a critical issue given that people living in developed in urban areas, and summarises current regulations, standards and countries typically spend 90% or more of their time guidance in the UK. It also includes short case studies to illustrate indoors, with the most susceptible individuals – such as the strategies for improving IAQ. Air pollutants and their sources 4 elderly and those with pre-existing medical conditions – spending almost all of their time inside (Crump et al, 2009).

Impact of poor IAQ on health, wellbeing and productivity 8 Creating good indoor environmental quality (IEQ) by improving factors such as indoor air quality, lighting and Indoor air quality standards and guidelines 9 acoustics, is increasingly recognised as improving occupant health and comfort, and physical and mental wellbeing. Regulation, standards and policies 9 It also provides opportunities to reduce healthcare costs. Selecting the most building-appropriate air quality standards and guidance 9 In 2015, for example, BRE updated its research into the cost of poor housing to the NHS and found that improving the Certification schemes 10 3.5 million ‘poor’ homes in England would save the NHS Indoor air quality monitoring 10 £1.4bn in first-year treatment costs alone.

Health and wellbeing have also risen up the agenda for Mitigating air pollutants in the indoor environment 11 companies who realise that unhealthy and poor-performing Control strategies 11 buildings directly impact their businesses. A growing body of evidence confirms that healthier buildings can lead to Reducing ingress of outdoor pollutants 12 happier and therefore more productive employees. The Outdoor air pollution source control 12 World Green Building Council, for example, states in its Building airtightness 12 2016 report ‘Building the Business Case: Health, Wellbeing and Productivity in Green Offices’, that employees account Ventilation air intake position 12 for 90% of a company’s operating costs. Just a 1% Ventilation air intake control 12 improvement will therefore have a significant impact on the bottom line. Developers and landlords also recognise Filtration 13 that healthy buildings can improve sales, command higher Control of ground pollutants 13 rental incomes, and attract and retain tenants in longer Reducing indoor pollutant emissions 14 term leases. Indoor air pollution source control 14 However, while health and wellbeing considerations have Ventilation and recirculation 15 emerged in certification schemes (e.g. BREEAM and WELL), Building Regulations and guidance such as the UK Air Filtration 15 Quality Strategy, there is still a lack of understanding of IEQ factors, particularly indoor air quality (IAQ). IAQ is complex Case studies 16 with many factors affecting it, including a wide range of pollutants and sources, and building types, locations and Investigation of a poorly-ventilated office building 16 décor. Exposure to different pollutants can cause varying The effects of cooking in an airtight home 16 health effects, from the worsening of asthmatic conditions and irritation of the skin, to premature deaths caused by Indoor air quality investigation at a school 17 heart and lung disease.

Appendix 18

References 22

Acknowledgements 23 4 Ensuring good indoor air quality in buildings Ensuring good indoor air quality in buildings 5

Building occupants may be exposed to a variety of airborne – Nitrogen dioxide (NO2). The main outdoor sources of NO2 are Air pollutants and their sources pollutants, including organic, inorganic and biological from combustion and transport. Major indoor sources of NOx are (in both gaseous and particulate forms). Of particular gas-fuelled cookers, and poorly-flued (or unflued) fires, water concern are airborne pollutants that have the potential heaters and space heaters. The types and concentration of air pollutants present in any to cause serious health effects or exacerbate existing indoor environment will vary according to the building type – Carbon monoxide (CO). This is a colourless, odourless gas conditions. These include: and location in relation to outdoor sources, construction produced by the incomplete combustion of most fuels. Incomplete and building systems, and internal content, furnishings and combustion can occur, for example, when inadequate ventilation – Volatile organic compounds (VOCs). VOCs comprise occupant activities. to an appliance results in depletion of the oxygen content of the a wide range of volatile chemicals, which may be emitted air at the point of combustion. Other sources of carbon monoxide over periods of weeks or years from construction and All types of domestic and non-domestic buildings, from can include smoking, the burning of candles and the ingress of the furnishing products. Examples include concrete and detached and terraced houses, to offices and airports, exhaust from internal combustion engines. are likely to be exposed to pollutants and their sources, masonry surface treatments, timber preservation and examples of which are shown in Figures 1 and 2. coatings, adhesives, sealants, paints and architectural – Particulate matter (PM). Particulate matter is made up of a coatings, damp proofing emulsions and membranes, complex mixture of solid and liquid particles suspended in the air. wall coverings, floor coverings, cove base, roofing These can include carbon, complex organic chemicals, sulphate, compounds, cleaning products, fungicide washes, fuels, nitrates, ammonium, sodium chloride, mineral dust, water and a spot removers, household cleaners, air fresheners and air series of metals. The main sources of PM are from combustion and cooling refrigerants for building services. transport. Construction and demolition activities are important local sources in urban areas. Particulate matter is also produced VOCs also arise from using consumer products such as by certain cooking activities (e.g. frying). The particle mass

aerosols used in cleaning and personal care products. fractions PM2.5 (up to 2.5 μm in diameter) and PM10 (up to 10 μm Carbon dioxide Other indoor sources include cooking, cigarette smoke in diameter) are commonly measured due to the significance of bioeffluents and plug-in air fragrances. VOCs from sources such these particle sizes with regards to the human respiratory system. VOCs Fire products Particles Biological as road traffic may also be drawn in from outside by – Biological pollutants. These include faecal pellets from house formaldehyde ventilation and infiltration. dust mites, mould, fungal particles, bacteria and pollen. Other – Formaldehyde. Formaldehyde is a very volatile organic allergenic particles may be present due to domestic animals Industrial Inorganic compound (VVOC) that is released directly into indoor air and pests.

pollutants pollutants Moisture Ammonia from various sources such as resins, phenol-formaldehyde – Moisture. Moisture arises generally from respiration and activities (NO , CO) and urea formaldehyde (UF) from wood-based products 2 such as cooking and washing. The amount of water vapour such as particleboard in furniture, UF-based lacquers and present in the air directly affects occupant health and comfort, UF foam cavity wall insulation. It is also a constituent of Traffic pollutants Tobacco Biological and also the presence of biological pollutants such as Ozone tobacco smoke and of combustion gases from fossil fuel (NO , particles) smoke pollutants mould spores. 2 Odour burning appliances.

– Odour. Common sources of odour discharges are ventilation – Carbon dioxide (CO ). CO sources are human and 2 2 extracts, including those from kitchens and restaurants, diesel animal respiration and combustion products. Plants also emissions, cooking, consumer products such as aerosols, Radon Methane Moisture give off carbon dioxide, but if (and only if) the light is cosmetics, plug-in air fragrances, cleaning and personal care bright enough to initiate photosynthesis, they can reduce products, and cigarette smoke. levels of carbon dioxide.

Figure 1. Examples of typical external (blue) and internal (orange) pollutants found indoors – Industrial pollutants. A variety of ‘industrial’ pollutants may be – Ozone (O ). O primarily arises from photochemical 3 3 generated in urban areas, for example from waste incinerators, reactions in the ambient air, and is also produced laboratory fume cupboards, vehicle spray booths, small indoors by some electronic equipment such as printers generation plant such as combined heat and power (CHP) and and photocopiers. Ozone may undergo reactions diesel-powered standby generators. with surfaces and other airborne pollutants indoors to produce new compounds and particles. – Ground pollutants. It is possible that gases from the soil beneath the building contain hazardous substances; these may be of natural origin such as radon released by the bedrock or be contaminants such as organic chemicals present because of previous historic uses Occupants, of the site or neighbouring land (Crump et al, 2004). pets Combustion Combustion Décor, Ventilation plant processes furnishings exhausts

Industrial Cooking Washing, Demolition processes cleaning construction

Road transport Smoking Decorating Fires Construction materials

Ground/contaminated land

Figure 2. Examples of typical external (blue) and internal (orange) sources of pollutants affecting IAQ 6 Ensuring good indoor air quality in buildings Ensuring good indoor air quality in buildings 7

Tables 1 and 2 show the relationship between pollutants, their sources and the indoor environments in which they are likely to occur.

Table 2. Examples of types of pollutants emitted from different sources likely to affect Table 1. Examples of types of pollutant sources found in different indoor environments indoor environments

Pollutant sources Pollutants

Consumer activities Pollutant Particles Volatile Biological/ Office Carbon Carbon Odour, Organic Formaldeh- Allergens Nitrogen Ammonia Internal Animals sources Moisture (PM10, Ozone (O ) Methane Radon Combustion equipment dioxide monoxide fragrances yde oxides 3 (NH ) environments Decorating (e.g. pets, Ground/ PM , dust, Compounds e.g. mould 3 Construction Furnishing Washing (CO2) (CO) 2.5 (NOx) Outdoor air products e.g. assistance Tobacco fibres) (VOCs) and spores (buildings only) paints, and People contaminated materials materials adhesives from e.g. gas photocopiers, dogs, pests, smoke land cleaning appliances electrical and mites) Outdoor air varnishes products goods Construction Domestic materials Furnishing Offices materials Decorating (Paints, Schools adhesives and varnishes) Hospitals Washing and cleaning Hotels products Combustion Restaurants products from e.g. gas Public places appliances e.g. museums Electrical Industrial / goods e.g. factories photocopiers Shops and People shopping malls (including personal care products)

Animals

Tobacco smoke

Ground 8 Ensuring good indoor air quality in buildings Ensuring good indoor air quality in buildings 9

Maximum concentrations are given for short-term (15 minute) Impact of poor IAQ on health, Indoor air quality standards and and long-term (8 hour) exposure limits in any 24 hour period. While largely relating to indoor emissions, these exposure limits wellbeing and productivity guidelines set values for indoor environments that should not be exceeded whatever the source. HSE does not set limits for continuous Poor indoor air quality can cause a range of health effects Regulations, standards and policies (24 hour) exposures and therefore the WELs cannot be regarded ranging from headaches, dizziness and nausea, to asthma, as safe concentrations for longer than the period given. cardiovascular disease, cancer and death. Table 3 shows There is limited information in the UK, and in fact the typical impact on occupant health and wellbeing of worldwide, on recommended concentration guidelines and f) European some common pollutants found indoors. As well as being standards specifically for indoor air pollutants. Those that In 2005, a European-funded study identified formaldehyde, exist are summarised in the following sections. detrimental to health and comfort, poor indoor air quality can CO, NO2, benzene and naphthalene as ‘Group 1’ high-priority adversely affect performance at work, learning in educational chemicals that could occur in high concentrations, pose a establishments and healing in healthcare settings. a) World Health Organization significant risk to the health of occupants and therefore In 2010, the World Health Organization (WHO, 2010) require risk management action (INDEX, 2005). The ‘Group The extent of the effect of a particular pollutant on human published guidelines for the protection of public 2’, second priority chemicals include acetaldehyde, toluene, health depends on its concentration and the duration health from risks due to a number of pollutants xylenes and styrene. These compounds could also occur in high of exposure. Any effect also depends on the age and affecting indoor environments including, benzene, concentrations indoors but the need for risk management action gender of the people occupying a space (CIBSE, 2011). carbon monoxide, formaldehyde, nitrogen dioxide, is considered less urgent. Most current data on the impact of air pollution on health polycyclic aromatic hydrocarbons (PAHs – especially apply to people in good health and, in the case of working benzo[ ]pyrene), radon, trichloroethylene and Guidelines for ventilation requirements in buildings published environments, to those aged between late teens (16-19) tetrachloroethylene. by the European Commission, includes recommendations by and normal retirement age (65 in the UK and Ireland). In some European authors for TVOC concentrations in indoor the industrial workplace many of the most serious risks The guideline values provide the basis for evaluation non-occupational environments (See Appendix, Table 4.1). are addressed with local exhaust ventilation, with residual of these pollutants to a level below which lifetime risk controlled by personal protective equipment (PPE) and exposure, or exposure for a given average time period, Selecting the most building-appropriate air quality exposure monitoring. However, in domestic and many non- would not constitute a significant risk to the health or domestic environments, the control of indoor air pollution well-being of people. standards and guidance may not be achieved as easily. The selection of appropriate air quality standards against which to b) Committee on the Medical Effects of Air Pollution compare the indoor environment in buildings needs to be carefully Workplace Exposure Limits (WELs) may apply for healthy In the UK, the Committee on the Medical Effects considered. In homes and buildings open to public access, such as people of working age who are exposed to a pollutant of Air Pollution (COMEAP) provides independent schools and hospitals, the World Health Organization guidelines directly as part of their work. For those people not in good advice to UK government departments and agencies and the objectives set by the UK Air Quality Strategy are the most health, and for those younger or older than working age on how air pollution impacts on health, and has appropriate. In more industrial environments, the Health and Safety people, lower (‘environmental’) exposure limits are usually published ‘Guidance on the Effects of Indoor Air Executive’s (HSE), Workplace Exposure Limits (WELs) are the most employed. These lower limits should also be applied if a Pollutants’ (COMEAP, 2004). COMEAP recommends suitable (HSE, 2011). person is exposed to the pollutant for significantly longer concentrations for formaldehyde, benzene, and PAHs than 8 hours, or if their work activity does not directly (as benzo[ ]pyrene equivalent). NO2 and CO are The HSE WELs are formally set as exposure limits for physically involve the pollutant. included in the recommendations for monitoring the fit individuals in the industrial workplace, exposed for a nominal indoor air of homes. eight-hour day, and a five-day week. The limits therefore exclude vulnerable groups including the elderly, young and infirm, those c) UK Building Regulations unusually sensitive to some pollutants, and those inhabiting a A ppendix A of Approved Document Part F of the building on a more permanent basis. Therefore, although typical Building Regulations (F1 Means of Ventilation) covering Table 3. Typical health impacts of some common pollutants found indoors office buildings are ‘workplaces’, it is doubtful whether the WELs performance-based ventilation (CLG, 2015), sets are necessarily the most appropriate for these buildings. The maximum acceptable indoor levels for nitrogen dioxide, occupants present in office environments generally represent a carbon monoxide and total volatile organic compounds Pollutant Impact on health wider distribution of society members, including those that are less (TVOC). These, in part, are based on values given by physically fit and able when compared with workers in industrial COMEAP (2004). Carbon Carbon monoxide can cause headaches, dizziness, nausea and at very high levels, death. Elderly people, pregnant women, settings. Also, if workers are not in contact with a pollutant as a monoxide (CO) young children and people with heart disease and lung disease are more sensitive to the adverse effects of carbon monoxide. direct part of their work, they may not be aware that they are being d) UK Air Quality Strategy exposed to it, and so appropriate precautions may not be in place. Formaldehyde Formaldehyde can cause eye, nose and throat irritation and is considered a potential human carcinogen. T he Air Quality Strategy (AQS) for England, Scotland, Her Majesty’s Inspectorate of Pollution (HMIP), recommended Wales and Northern Ireland (DETR, 2000; Defra, 2007) (1993) that for the exposure of the general populace, a fraction of Exposure to nitrogen dioxide can cause inflammation of the airways, respiratory illnesses and possibly increases the risk sets out policies for the management of ambient air the guidelines given in the HSE WELs should be used. Nitrogen of lung infections. Young children and people with asthma are the most sensitive to NO2. It plays a major role in the quality. These include air quality objectives for 10 key air dioxide (NO2) development of chronic obstructive pulmonary disease in adults which will affect more people than heart disease by 2020 pollutants in order to protect people’s health and the In view of this, it is more appropriate in office environments to use (Environmentalist 2012). Long-term exposure may also affect lung function and can enhance responses to allergens in environment without unacceptable ‘economic or social sensitised individuals. the far lower outdoor air quality guidelines set for exposure of the costs’. These are Particles (PM10 and PM2.5), NO2, O3, general populace, as a part of the UK Air Quality Strategy (Defra, sulphur dioxide (SO ), PAHs, benzene, 1,3 butadiene, Odour Odorous discharges are subjective and cause nausea and irritation for some people. 2 2007) and the World Health Organization guidelines. For pollutants carbon monoxide (CO), and lead. not covered by these, the HMIP (1993) recommended limits may Ozone (O3) Ozone exposure can cause asthma, irritation and damage to the eyes, nose and airways. Prolonged exposure to high levels be used. may result in damage to the lungs and airway linings. e) Health and Safety Executive (HSE) The Health and Safety Executive supports the regulatory For a summary of recommended guidelines for a number of air Inhalable particles have been linked with a number of respiratory illnesses, including asthma and chronic bronchitis. Long- framework for workplace health and safety in England, pollutants found indoors, please refer to Tables 4.1 to 4.9 in Particulate term exposure to fine particles can cause premature death from heart disease and lung disease including cancer. Short-term Wales and Scotland (in Northern Ireland this is covered the Appendix. matter exposure to higher levels of fine particle concentrations have also been linked with cardio-vascular problems and increased by HSENI) through the Health and Safety at Work Act death rates. Exposure to fine particles has also been linked to prevalent anxiety and hypertensive disorders. (HSE, 1974). Specific pollutants are covered by the Volatile organic Control of Substances Hazardous to Health Regulations Key symptoms associated with exposure to VOCs include eye irritation, nose and throat discomfort, headache and allergic compounds skin reaction. 2002 (HSE, 2002). Within this Act, approximately 500 (VOCs) substances have been set legally-binding Workplace Exposure Limits (WELs) which are listed in document EH40 (HSE (2011 and subsequent revisions)). 10 Ensuring good indoor air quality in buildings Ensuring good indoor air quality in buildings 11

Certification schemes Indoor air quality monitoring There are a number of environmental assessment schemes In general, indoor air quality monitoring can often be carried out that award credits to new developments and building by using outdoor air quality monitors. Outdoor air quality is highly refurbishments if the air quality meets certain specified regulated and therefore outdoor air pollutant measurements require criteria. These are usually based on either the UK Air Quality the use of specified reference methods and equipment in order for Strategy or the WHO Guidelines. The major schemes of this the results obtained to comply with relevant air quality legislative type are BREEAM (2014a and 2014b), LEED (USGBC, 2016) requirements. In general, the pollutants covered are mainly those and WELL (IWBI, 2016). regulated as a part of the UK Air Quality Strategy (Defra, 2007). Thus, the assessment mechanisms for both indoor and outdoor BREEAM (Building Research Establishment’s environments are the same. Environmental Assessment Method) Much of the instrumentation and personal sampling equipment ‘BREEAM UK New Construction: Non-domestic buildings’ available for indoor monitoring is suited to more industrial-type (BREEAM, 2014a) contains a section on indoor air quality, workplaces. These workplaces generally have more fit and healthy including measures for preventing the ingress of outdoor occupants, and so it typically measures airborne pollutants in the Mitigating air pollutants in the pollutants. It covers pollutant removal, requirements on air occupational range (with concentrations in the ppm or mg m-3 intake and exhaust positioning, HVAC system filtration, the range). For office-type and other environments, where occupant indoor environment use of carbon dioxide and other indoor air quality control fitness and health are closer to that of the general population, sensors, restrictions on total volatile organic compounds instruments operating in the ‘environmental’ range (with Control strategies (TVOC) and formaldehyde emissions and the performance concentrations in the ppb or µg m-3 range) are usually more suitable. of actuator, vent and window controls. Recognition is given Control strategies for reducing the concentration of air pollutants in the indoor environment depend on the type for the provision of fresh air. Nonetheless, with careful selection there is equipment available and location of the source and activity. Ventilation with that can be used to monitor the indoor environment for a variety outdoor fresh air, will dilute and flush out pollutants derived BREEAM Section 5: Health and Wellbeing: HEA02 of potential airborne contaminants. The results obtained from such from indoor sources but will not eliminate them completely. Indoor Air Quality (BREEAM, 2014a) focusses on VOCs IAQ monitoring can then be compared against available air quality In fact, the incoming ventilation air may itself be polluted and formaldehyde in particular and awards credits for standards and guidelines, such as the UK Air Quality Strategy, the from outdoor sources, which will place an additional complying with set requirements. It encourages a healthy World Health Organization Air Quality Guidelines (WHO, 2010), burden on indoor air. Care therefore needs to be taken in internal environment through specifying and installing and the Health and Safety Executive Workplace Exposure Limits as selecting the correct mitigation strategy to give optimum appropriate ventilation, equipment and finishes. Indoor appropriate (HSE, 2011a). pollutant measurements made to establish compliance indoor air quality for health and wellbeing (Figure 3). must meet relevant British Standards. Such measurements There are some measurements, for example, for volatile organic must be taken in representative habitable rooms, with compounds (VOCs) where standards and guidance for indoor the building having been in operation for a period of time monitoring exist (BS, 2011). However, there are few specific sufficient to ensure that equilibrium has been reached in methodologies for general IAQ monitoring. Outdoor air Indoor air terms of internal environmental conditions. pollutant sources pollutant sources Where present, HVAC systems must incorporate suitable filtration to minimise external air pollution, as defined in BS EN 13779:2007 Annex A3 (BS, 2007). This therefore links BREEAM to a standard that requires the quality of outdoor air to be taken into account. Further credit is also given for Poor IAQ having an air quality plan for the building/development.

WELL

The WELL Building Standard (IWBI, 2016) was launched in 2015 in the USA and is primarily aimed at creating healthier work and living spaces. It is primarily performance-based and was developed by integrating scientific and medical Mitigation strategies research to address the complex issues of human health and wellbeing in relation to the built environment. The Outdoor: Indoor: standard contains 29 air quality-related areas to be – Source control – Source control addressed, including relevant standards, ventilation, VOC – Airtightness – Ventilation reduction, filtration, cleaning, monitoring and feedback. – Intake location and control – Recirculation – Filtration – Filtration LEED (Leadership in Energy and Environmental Design) LEED is a building certification programme developed by the US Green Building Council (USGBC, 2016). It includes a set of rating systems for the design, construction, operation, and maintenance of buildings, homes, and neighbourhoods to help building owners and operators be environmentally responsible and use resources efficiently. Optimum IAQ for It includes minimum air quality and ventilation performance health and wellbeing requirements to contribute to the comfort and wellbeing of building occupants. Parameters to be monitored for

compliance include VOCs, formaldehyde, particles (PM10) and carbon monoxide. Figure 3. Air pollution mitigation strategies to give optimum indoor air quality 12 Ensuring good indoor air quality in buildings Ensuring good indoor air quality in buildings 13

Reducing ingress of outdoor pollutants Ventilation air intake position Guidance on reducing the ingress of outdoor pollution The effective location of ventilation air intakes is important for covers the following main strategies (Liddament, 1996; reducing the ingress of local sources of air pollution. Guidance CIBSE, 1999; CLG, 2010a; Kukadia and Hall, 2011; available is given by CIBSE (1999), Approved Document Part F Cheng et al., 2014; Kukadia and Abela, 2015): (Appendix D) of the UK Building Regulations (CLG, 2010), Kukadia and Hall, 2011 and Cheng et al., 2014. 1. Outdoor air pollution source control Recommended guidance includes: 2. Building airtightness 3. Ventilation air intake position – Ventilation intakes need to be placed away from the direct impact of short-range pollutant sources, such as roads, especially if they 4. Filtration are within a few metres of the building. Inlets for mechanical systems can be placed on the roof to avoid ground-based Further information on these is covered in the following pollutant sources, if no other sources are present at high level. sections. – If intakes are to be located higher up a tall building then cross- Outdoor air pollution source control contamination from, for example, exhaust stacks and boiler flues, needs to be considered carefully and avoided. Air pollutant emissions from sources, such as vehicles and industrial processes, are controlled by various legislation, – Ventilation intakes can be placed in courtyards and enclosed regulation and guidance. However, despite such control spaces as they can offer protection for air intakes. However, care Filtration measures being in place, outdoor air pollution levels in needs to be taken to ensure that emissions from sources such as Filtration is used to physically remove particles, and in the UK are still relatively high and likely to be so in the loading areas, ventilation extracts, boiler discharges or kitchen some cases environmental gaseous pollutants, from the foreseeable future. Therefore, additional measures are odour are not discharged into such spaces directly. In general, ventilation air supply. Virtually all mechanical ventilation required to reduce the ingress of outdoor pollutants into pollutants discharged directly into courtyards disperse and clear systems incorporate some form of filtration, but this is the indoor environment (Kukadia and Hall, 2011). slowly, therefore posing a potential risk. usually primarily to protect the HVAC system rather than Ventilation air intake control to improve air quality. In the UK, filtration performance Building airtightness standards are specified by BS EN 779, BS EN 1822 and BS Control of ground pollutants Recommended guidance includes: EN 14387 (BSI, 2012a, 2009, 2008) and CIBSE Guide B Once a contaminant from an outdoor source has reached a Pollutants in soil gas, such as radon and organic chemicals emitted building, the extent of pollutant ingress will depend on the (CIBSE, 2004). – For pollutant sources such as urban road traffic, where beneath the building, can be stopped from entering the indoor airtightness of the building envelope and number and size environment with impermeable membranes in the floor structure, of openings, as well as the ventilation strategy. concentration fluctuates with the time of day, it is recommended It should be noted that filtration systems are selective and that the flow of external air is reduced, or ventilation intakes are are only effective at dealing with the pollutants for which or by other means. The Building Regulations provide advice on design measures to minimise ingress of both polluted ambient air Adventitious gaps and cracks in the building envelope closed, for up to an hour during peak periods such as rush hours. they are designed. Air intakes located on a less polluted side of the building may then (CLG, 2010a) and ground pollutants, including moisture, (CLG, contribute to the air permeability of the building, the 2006a). They also require appropriate works to prevent foul air from subsequent uncontrolled infiltration of outdoor air and be used for fresh air or, for a short time air can be fully Particle filtration performance re-circulated within the building. drainage systems entering the building (CLG, 2006b) and ensure hence pollutants. Therefore, reducing air permeability Basic filters are used to remove large particles such as dust the adequate generation of air for fuel combustion in heating by sealing the building envelope, and increasing its – The building may be used as a ‘fresh air’ reservoir (Liddament, but they offer little protection against smaller, respirable appliances, and appropriate provision of flues for the removal of airtightness, will help reduce air ingress and so air pollution. 1996) to supply air during short local pollution episodes. The use particles. These are classified as ‘General’ or ‘G’ filters, and fumes (CLG, 2010b). of atria as a source of ‘fresh air’ for this purpose may also be in advanced ventilation systems will form part of a pre-filter. The Approved Document Part L of the Building Regulations an option. In the UK, higher specification particle filters are classified in England, requires that the air permeability should not in increasing order of effectiveness as follows: exceed a limiting or worst-allowable value of 10 m3 /(h.m2) at 50 Pa pressure difference. However, in practice, the – Medium (‘M’ type filters) actual design air permeability applied to satisfy energy and – Fine (‘F’ type filters) CO2 emission targets, is often much lower and may typically be of the order of 5 m3 /(h.m2) at 50 Pa. – Efficient Particulate Air (EPA or ‘E’ type filters) – High Efficiency Particulate Air (HEPA or ‘H’ type filters) – Ultra-Low Penetration Air (ULPA or ‘U’ type filters)

A full discussion of filtration classification is given in CIBSE Guide B.

Contaminant gas and vapour removal This is a specialist topic where expert advice needs to be sought, as it is not commonly applied in standard building filtration systems. However, where needed, tertiary adsorption filters (for example activated carbon) may be fitted, taking into consideration the specific contaminants for which they have been designed. An integrated and balanced approach needs to be taken when designing for these systems. 14 Ensuring good indoor air quality in buildings Ensuring good indoor air quality in buildings 15

Reducing indoor pollutant emissions Low-emitting products and labelling schemes Ventilation and recirculation Guidance on reducing indoor pollution covers the following Air pollutants are emitted from materials and products used Ventilation is most suited to providing fresh air for occupants’ main strategies: in construction, decoration and furnishing. A greater use of respiration, and to diluting and removing unavoidable pollutants. low-emitting products will help to reduce the pollution load These include those generated by occupants themselves (metabolic 1. Indoor air pollution source control in buildings and the risk of accumulating high pollutant levels. carbon dioxide and odour), as well as pollutants from activities including cooking and washing. Localised sources of pollutants, such 2. Ventilation Low-emitting products will only reduce some types of as those generated by cooking, washing, clothes drying and use 3. Recirculation pollution from some of the wide range of indoor sources. of office equipment, should be extracted at source by localised or Therefore this approach is only one part of an effective central ventilation extraction. In each case the extract hood location 4. Filtration strategy for indoor air quality management. Other pollution needs to be close to the source. Details of suitable ventilation sources, such as cooking and heating, people and pets, strategies are given in Part F of the Building Regulations (CLG, 2016). Indoor air pollution source control radon from the ground, water vapour and residual VOC emissions from ‘low-emitting’ products, also need to be In mechanically ventilated commercial buildings, ‘recirculation’ There is currently a lack of awareness amongst occupiers managed. Source control provides substantial benefits, of buildings, that certain activities (for example, smoking, of part of the indoor air almost always occurs, so some form of but does not preclude the need for adequate ventilation to filtration, especially for particles, is normally required. Sometimes using scented candles, painting and decorating) pollute the achieve a healthy indoor environment. indoor environment and can cause adverse health effects. re-circulatory systems are used in the home, often to control allergy- type problems. To be effective, such systems must have a flow rate It is likely that if occupants were more aware of this they There are various labelling schemes for products and would try to keep such activities to a minimum or ensure that is much greater than (typically two or three times) the outdoor materials used in the construction and fitting out of air ventilation rate. that appropriate measures (such as purge ventilation) are buildings. Most of these focus primarily on characteristics used as mitigation. such as sustainability and embedded energy use, but Filtration some now also cover the emission of chemicals such as A common misconception is that dilution with fresh formaldehyde and VOCs. However, these schemes are Indoor air can be cleaned by filtering, and then recycled within the ventilation air is the only way of removing harmful currently voluntary rather than mandatory. building or room. Filtration systems can range from those that treat contaminants from the occupied space. It is more effective air in the mechanical ventilation system of the building, to devices to control the source of pollutant, if possible, especially Also, some emissions are expressed in units of µg m-3, in individual rooms that may be fixed or stand-alone. Also, passive as outdoor air may itself be contaminated. Preventing and these could be confusing when room concentrations products, such as wall materials with enhanced properties for indoor air quality problems by source control is generally are also expressed in units of µg m-3. A product with absorbing some pollutants, are available on the market – though less expensive than identifying and solving them after they emissions of, say 50 µg m-3, could be used but the resulting the efficacy of these is as yet unproven. occur. The generation of internal pollution can be avoided, concentrations in a room could be several hundred µg m-3. for example, by using low-emitting furnishings and This is because emissions are calculated using a standard carpeting and discouraging pollutant-emitting activities. area in a standard sized chamber, and the application rate in a room could differ from the measured sample area to The Building Regulations, Approved Document F(F1 chamber volume ratio. Means of Ventilation) 2006, emphasises the need for a complementary strategy of ‘source control’ by reducing the release of volatile pollutants into the indoor air. Particular sources include formaldehyde and VOCs from building components, fabrics and furnishings.

The Zero Carbon Hub (ZCH, 2012), recommended that particular products or components be banned from use indoors. Examples include asbestos products, lead in interior paint, and prohibiting smoking in enclosed public spaces and workplaces. It further recommended the use of products with low or zero emission of pollutants. 16 Ensuring good indoor air quality in buildings Ensuring good indoor air quality in buildings 17

The effects of cooking in an airtight home Indoor air quality investigation at a school – Thermal comfort assessment (temperature and relative humidity). Case studies Measurements of ventilation rate and various air quality parameters Following health-related concerns from staff at a – Inspection of heating and air handling systems (including were carried out under relatively controlled conditions in a modern, newbuild school, BRE was commissioned to evaluate the controls). Investigation of a poorly-ventilated office airtight home (built to meet the Code for Sustainable Homes – ‘Level environmental conditions in the school. A comprehensive – Air quality monitoring (CO, CO2, particulate matter, SO2, NO2, building 6’). The aim was to investigate the effect of different types of fuel four-week programme of surveys, inspections, monitoring VOCs, formaldehyde). (electricity and gas), cooking (boiling, frying) and ventilation rate. and testing was carried out by BRE in order to fulfil the BRE investigated an office building where the staff had requirements of a detailed tender specification document, – Airtightness and air change rate measurements. concerns over inadequate ventilation provision, and the Findings included the following: with over-arching objectives, including investigation of – Lighting assessment (daylight; electric lighting; glare; task-based possible health effects of any resulting poor air quality. factors that may have led to ill health of building occupants, lighting). The building had been significantly modified since its – frying food produced more air pollutants than boiling, assessment of occupant comfort, and verification of original design and some of the ventilation system whether the school building complied with Building – Background noise assessment. – the use of gas as a cooking fuel produced more nitrogen oxides components were no longer fully operational. Regulations and contractual and statutory requirements in (NO ) and fine particles, x terms of air quality and environmental conditions. BRE’s findings were presented in a full technical report, and later in Measurements were made of the building ventilation – the ventilation system in the house did not provide a significant person to senior educational officers at the local authority. The main rate, and the concentrations of various potential air change in ventilation rate when operated in the ‘boost’ mode as A full programme of inspections, snap-shot measurements findings and recommended remedial actions were also presented pollutants including carbon monoxide, carbon dioxide, compared with the ‘normal’ mode, and continuous monitoring was undertaken, including: in layman’s terms to school staff and to maintenance staff working VOCs, formaldehyde and particles. With the exception for the school’s contracted facilities management organisation. This of carbon dioxide, the results showed that no significant – with the ventilation system off (to simulate a potential failure), included guidance on use of features such as trickle vents and concentrations of air pollutants were present. However, many of the air pollutants remained in the house for long periods HVAC controls. the carbon dioxide measurement results showed that the of time. building was very poorly ventilated, with concentrations BRE was later commissioned to undertake follow-up monitoring to at levels that would have potentially significant effects on The ventilation system in the house had been very poorly verify that remedial actions had been effective. occupant performance and productivity. Recommendations installed and maintained (despite the high-profile nature of the were made on how the ventilation system could be adapted development), rendering it incapable of delivering the required and improved to enhance the air quality in the building, in background (purpose-provided) and purge ventilation when both the short and longer term. required. This highlights the need for checking that building ventilation rates specified at the design stage of a project are actually delivered in practice, both post-construction and post-occupancy. 18 Ensuring good indoor air quality in buildings Ensuring good indoor air quality in buildings 19

Table 4.4(a). Guideline concentrations for carbon dioxide, CO2 Appendix

Carbon dioxide, CO2 Table 4.1. Guideline concentrations for Total Volatile Organic Compounds (TVOCs) Guideline concentration mg m-3 (ppm) Averaging time

Total Volatile Organic Compounds (TVOCs) 9,150 (5,000) 8 hour mean UK HSE Workplace Exposure Limits 27,400 (15,000) 15 minute mean (short-term exposure limit, STEL) Guideline concentration μg m-3 Averaging time Performance standard to indicate CIBSE Guide A ~1,000 ppm UK Building Regulations, ‘adequate ventilation’ 300 8 hours Approved Document F

European 200 to 500

Guideline concentration μg m-3 Comment Table 4.4(b). Recommended guideline concentrations for CO2 levels (BS EN 13779:2007) in rooms <200 Comfort range

200-3,000 Multifactorial exposure Mølhave, L Carbon dioxide – level above level of outdoor air in ppm 3,000-25,000 Discomfort Typical range Default value >25,000 Toxic

300 Target guideline value. No individual compound IDA 1 <=400 350 Seifert, B should exceed 10% of target value IDA 2 400-1,000 500 <200 Target values of indoor climate; best air quality; 90% of occupants satisfied IDA 3 600-1,000 800 Finnish Society of IAQ and Climate <300 Room may have a slight odour IDA 4 >1,000 1,200

<600 Minimum requirement

Table 4.5. Guideline concentrations for nitrogen dioxide, NO2 Table 4.2. Guideline concentrations for formaldehyde

Nitrogen dioxide, NO2

Formaldehyde Guideline concentration μg m-3 (ppb) Averaging time

-3 Guideline concentration μg m Averaging time 200 (105) 1 hour mean World Health Organization (WHO) World Health 30 minute mean based on effects other 40 (21) Annual mean 100 Organization than cancer or odour/annoyance 200 (105) 1 hour mean COMEAP COMEAP 100 30 minutes 40 (21) Annual mean 2,500 8 hour mean UK HSE Workplace 288 (150) 1 hour mean Exposure Limits UK Building Regulations, 2,500 15 minute mean (short-term exposure limit, STEL) Approved Document F 40 (21) Long-term INDEX 30 Non-carcinogenic no-effect level 200 (105) with a maximum of 18 exceedances allowable 1 hour mean UK Air Quality Strategy within any 12 month period

40 (21) Annual mean Table 4.3. COMEAP guideline concentrations for benzene and benzo[ ]pyrene

Pollutant Guideline concentration Averaging time

Benzene 5.0 μg m-3 (1.6 ppb) Annual mean

Benzo[ ]pyrene 0.25 ng m-3 Annual mean 20 Ensuring good indoor air quality in buildings Ensuring good indoor air quality in buildings 21

Table 4.6. Guideline concentrations for carbon monoxide, CO Table 4.8. Guideline concentrations for sulphur dioxide, SO2 Carbon monoxide, CO Sulphur dioxide, SO2 Guideline concentration Averaging time mg m-3 (ppm) Guideline concentration Averaging time µg m-3 (ppb) 100 (85) 15 minute mean* 20 (8) 24 hour World Health 35 (30) 1 hour World Health Organization (WHO) Organization (WHO) 500 (188) 10 minute 10 (9) 8 hours 1 hour mean concentration not to be exceeded 350 (130) 7 (6) 24 hours** more than 24 times a year

100 (90) 15 minutes 24 hour mean concentration not to be exceeded UK Air Quality Strategy 125 (47) more than 3 times a year 60 (50) 30 minutes COMEAP 15 minute mean concentration not to be exceeded 266 (100) 30 (25) 1 hour more than 35 times a year 10 (10) 8 hours

100 (90) 15 minutes

60 (50) 30 minutes UK Building Regulations, Approved Document F Table 4.9. Guideline concentrations for particles 30 (25) 1 hour

10 (10) 8 hours Particles UK Building Regulations, 35 (30) 8 hour occupational exposure Approved Document F PM10 PM2.5 Averaging time µg m-3 µg m-3 UK Air Quality Strategy 10 (10) 8 hours World Health 20 10 Annual mean Organization (WHO) UK HSE Workplace 35 (30) 8 hour mean Exposure Limits 232 (200) 15 minute mean (short-term exposure limit, STEL) EU Ambient Air Quality 50 25 24 hour mean Directive and current UK Air Quality Standard 50 24 hour mean *Assuming light exercise and that such exposure does not occur more than once per day.

**Assuming that the person is awake and alert, but not exercising. It is recognised that someone would not be expected to be awake and alert for the whole 24 hour period.

Table 4.7. Guideline concentrations for ozone, O3

Ozone

Guideline concentration Averaging time µg m-3 (ppb)

World Health Organization (WHO) 100 (50) 8 hour mean

UK Building Regulations, Performance criteria – buildings other 100 (50) Approved Document F than dwellings

8 hour mean concentration not to be exceeded UK Air Quality Strategy 100 (50) more than 10 times a year

UK HSE Workplace 400 (200) 15 minute short-term exposure limit (STEL) Exposure Limits 22 Ensuring good indoor air quality in buildings Ensuring good indoor air quality in buildings 23

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PEN 03 19 © BRE March 2019 March 2019 March Upton Stuart and Kukadia Vina in buildings indoor quality air good Ensuring www.bregroup.com