Principles of air quality management
Air contains many different types of gases and particles. Good air quality is a key determinant of human health so emissions to air that are known to have detrimental health impacts are all closely regulated. However, air pollution levels and links to respiratory illness continue to be a major UK environmental concern.
Indoor air quality is affected by human activities, heating and ventilation systems, positioning of air intakes and extracts, and the materials used in a building fit out. It can also be adversely affected by gases entering the building from the ground, notably radon and, in some circumstances landfill gas and other contaminants. In Hertfordshire (and much of the UK), the primary cause of external air quality problems is road traffic.
Development often pays little attention to enhancing internal air quality, other than to comply with mandatory legislation. The basic principles of maintaining/improving air quality in construction and development are listed below.
Minimise dust and other emissions during construction activities
Construction and demolition activities can generate significant air quality problems; not only emissions arising from site activity, but also emissions arising from construction vehicles. Construction site dust typically comprises small particles such as soot and cement and larger particles such as grit, sand and wood dust; many of which are known to have detrimental health effects. In addition to generating significant vehicular emissions, construction traffic also contributes to local congestion and can generate nuisance impacts.
Active management of site activities and vehicular movements should be a priority in all development. Site management solutions are presented on the following pages. This can help towards achieving BREEAM and Home Quality Mark (HQM) credits through the Considerate Constructors Scheme.
Design out known pollutants
A number of commonplace products are known to contain airborne pollutants. Examples of these include some types of synthetic floor finishes and timber composite products. Numerous alternatives are available that perform similarly or better in terms of aesthetic quality, functionality and cost. Consequently, designing out known pollutants can be readily achieved. Similarly, well designed building services and the adoption of sufficient levels of ventilation can alleviate many air quality problems. For example, specifying low polluting boilers. Design solutions are presented on the following pages. This can help towards achieving BREEAM and HQM credits in a number of areas.
In addition, installing electric vehicle charging points can encourage the uptake of electric vehicles, reducing the number of polluting diesel and petrol vehicles.
Manage atmospheric emissions during building operation
In addition to emitting carbon dioxide emissions, buildings and operations within buildings also generate a number of other pollutants. For example, refrigerants that escape from air conditioning systems, NOx emissions from boilers and domestic hobs, or aerosol cleaning products. Effective reduction of these emissions is best managed by designing out the emissions; e.g. installing a refrigerant recovery system, specifying a low NOx boiler or changing cleaning products; however regular maintenance and installation of a building management system that, for example, identifies peaks in emissions can also help. Management solutions are presented on the following pages.
Benefits of air quality management
The selection of an appropriate range of air quality management solutions can deliver significant benefits, notably:
- social and economic benefits, for example:
- less respiratory and other sick building/stress related illness
- less sick days taken by workforce/population (and subsequent higher productivity)
- less need for healthcare expenditure
- environmental benefits, for example:
- improved air quality
- better management of resources
- Less emissions to air, often arising from inefficient equipment.
- increased amenity value of development
A: Openable windows/air intakes located adjacent to sources of external pollution.
B: Synthetic carpets can release toxins with VOCs.
C: Furnishing and finishing products such as paints release VOCs.
D: NOx emissions from boilers.
E: Office equipment, such as photocopiers and printers release VOCs.
A: Houseplants can improve air quality.
B: Building is sealed on any side adjacent to sources of external air pollution, including traffic, exhaust from porcesses or building services, etc.
C: Specification of low solvent content fixtures and fittings reduce the levels of VOCs, for example using water based paints and varnishes and avoiding chipboard and particle board in furniture.
D: Openable windows in orientations away from pollution.
E: Reduced NOx emissions from high efficiency boilers; additionally efficient
homes with a low heat demand (such as Passivhaus) have reduced emissions from
F: Large scale office equipment separate from main working area and appropriately ventilated.
G: All internal areas adequately ventilated; additionally where mechanical ventilation
with heat recovery (MVHR) is installed air can be filtered for pollutants
H: Electric vehicle charging points to encourage the uptake of electric vehicles and reduce the number of polluting vehicles
Causes and consequences of poor internal air quality
Inadequate levels of humidity, whether too high or too low, can compromise the internal air quality of a building. Humidity levels are primarily influenced by the suitability of the ventilation. Humidity levels that are either too high or too low are easily identified. Extreme levels have negative impacts on the health of building occupants and the life span of internal fittings.
Negative health effects of an internal dry atmosphere include dry skin and eyes.
Effects on the building interior include:
- Dulling of polished surfaces.
- Damage to wooden furniture and fittings.
Negative health effects of a moist atmosphere include:
- Respiratory illness due to increased levels of mould spores and dust mites which thrive in moist environments.
Effects on building interiors are greater than those for a dry environment. These include:
- Mould and mildew.
- Damp or wet walls.
- Damaged wallpaper and plaster boards.
- Warped doors and windows.
- Less efficient heating plant.
Particular types of service/retail outlet such as hairdressing salons, dry cleaning outlets, and restaurants can release overpowering smells which often cause nuisance impact to neighbouring residents and workers.
Dust is generated by many daily activities, including the construction process. Activities such as demolition, mixing, blasting, cutting, grinding, etc. can all generate high levels of dust, if best practice attenuation measures are not adopted. Dust is a well-known cause of respiratory irritation. Substantial amounts of dust in an operational building can present a significant problem for allergy sufferers.
Before the health impacts were known, Asbestos was considered to be the perfect fire retardant material. It can therefore be found in many existing building components including:
- storage heaters
Asbestos poses a very high risk to human health, as it is carcinogenic and via inhalation can lead to lung, chest and abdominal cancer. Mesothelioma is an asbestos related lung cancer and there were 2,515 deaths from this in Great Britain in 2014. The latest projections suggest that there will continue to be around 2,500 deaths per year for the rest of this current decade before annual numbers begin to decline. Research suggests there are currently about as many lung cancer deaths attributed to past asbestos exposure each year in Great Britain as there are mesothelioma deaths.
Asbestos has long been prohibited from any building works and asbestos management and removal is highly regulated. More information can be found on the Healthy and Safety Executive website.
Volatile organic compounds
Volatile Organic Compounds (VOCs) are air borne substances that are released from materials and furnishings such as plastics and MDF, finishing products such as paints and varnishes and office equipment such as photocopiers. External sources of VOCs include motor vehicles and aircraft. Known human health hazards arising from inhalation of VOCs include:
- Breathing difficulties.
- Eye, skin and throat irritation.
- Allergic reactions.
- Increased risk of lung disease.
Biological contaminants include bacteria, moulds, pollen and viruses, which can occur in stagnant water accumulated in ducts, humidifiers and drains, or water stained ceiling tiles, carpeting or insulation. Other sources of biological contaminants include insects or birds droppings.
Common health impacts include:
- Chest tightness.
- Muscle aches.
- Various forms of allergic responses.
One particular type of bacteria posing extreme risk is Legionella, which causes Legionnaire’s Disease (a fatal form of pneumonia), and Pontiac Fever. Legionnaire’s disease develops in poorly maintained and intermittently used water tanks and plant, boilers and pipework. Clear design guidance on how to remove all Legionnaire’s risk from building services is available from the Chartered Institute of Building Services Engineers (CIBSE).
Sick building syndrome
Sick Building Syndrome can be caused by the range of factors explained above, such as airborne pollutants released from buildings, VOCs, low humidity, ozone, dust mite and also glare. Common symptoms listed by the NHS include lethargy, stuffy or runny nose, dry throat, headache, eye irritation, chest tightness and dry skin.
Building services emit a large proportion of major greenhouse gases such as Carbon Dioxide (CO2), Sulphur Dioxide (SO2) and Nitrous Oxides (NOx), and various other gases.
Buildings account for around 20% of UK annual Sulphur Dioxide (SO2) and Nitrous Oxides (NOx) emissions. These two gases contribute to the acidification process, which pollutes soils, watercourses and forestry. Acidification also damages limestone buildings and statues.
In addition to SO2 and NOx, other key air pollutants generated by building services include refrigerants (used in air conditioning). Although refrigerant gases are mostly inert and consequently do not present a threat to human health, they have Global Warming Potential and can also contribute to Ozone Depletion. This means that when they leak/are accidentally released from air handling units, fan coils and chillers, they contribute significantly to ozone depletion and the greenhouse effect.
PM10 are particles that have a diameter of less than 10µm. Road traffic is the primary source of particulates outdoors. Sources of internal particulates include smoking, burning of candles, coal or wood fires and cooking. Health implications arising from the inhalation of these solid substances are:
- Eye irritation.
- Nose, throat and respiratory disease.
- Bronchitis, emphysema and heart disease can be caused when those particles are absorbed into the blood stream.
Oxides of nitrogen are one of the principal air-quality pollutant emissions from petrol, diesel, and alternative-fuel engines. The Euro emissions standards regulate these emissions. Modern cars, if kept in good condition, produce only quite small quantities of NOx, but the emissions from large numbers of cars add to a significant air quality problem.
Other sources of NOx include combustion of fossil fuel based boilers, and potentially from Biomass burners too.
NOx emission levels depend more on vehicle technology and the state of maintenance of the vehicle. Unlike emissions of CO2 emission of NOx is less dependent on fuel consumption. Other factors, such as driving style, driving conditions and ambient temperature also affect them.
High levels of exposure have been linked with increased hospital admissions due to respiratory problems, while long-term exposure may affect lung function and increase the response to allergens in sensitive people. NOx also contributes to smog formation, acid rain, can damage vegetation, contributes to ground-level ozone formation, and can react in the atmosphere to form fine particles (‘secondary particles’).