Air Pollution and Indoor Air: is this ‘invisible’ danger becoming more visible?

As highlighted in the recent GRESB ‘Health & Well-being in Real Estate’ report on market trends, over the last few years there has been an increased focus and consideration of health and well-being related issues across the entire real estate industry. Over this same period, there has been a growing awareness of the health impacts of air pollution (the so-called ‘invisible killer’), most notably surrounding emissions from road transport.

The health effects of outdoor air pollutants including nitrogen oxides (NOx), particulate matter (PM) and ozone are well established, with both short- and long-term exposure linked to conditions such as heart disease, stroke, lung cancer and respiratory illnesses. Research continues to find links between air pollution and health effects; a recent study has associated short-term exposure to PM with increased symptoms of psychiatric disorders, such as anxiety, in children. The recent ‘Dieselgate’ scandal has raised the profile of the continuing and persistent problems with air quality in many urban areas around the world.

Many national and local governments have now acknowledged that there is a significant problem with road transport-related air pollution. Consequently, decisions and actions are starting to be taken to try to address the issue, such as the UK and French governments’ plans to phase out the sale of petrol and diesel vehicles by 2040, and the introduction of ‘clean air zones’ in some cities (e.g. the ‘Ultra Low Emission Zone’ in central London). While the real estate sector can help to play its part in reducing its impacts from road transport-related air pollution (e.g. through consideration of an asset’s location in investment decisions, and through organisational policies on vehicle fleets, commuting, deliveries, etc.), ultimately it will be policies, regulations and initiatives implemented at the national and local level that will drive and lead to significant improvements in external air quality.

The increase in awareness of external air pollution amongst the general public has, unsurprisingly, also led to a growing interest in the quality of indoor air within buildings. While NOx and PM are pollutants of concern in indoor as well as outdoor air, other indoor air pollutants of concern include carbon monoxide, formaldehyde, volatile organic compounds (VOCs) and radon. Given that the average person in the developed world spends the vast majority of their time indoors within buildings, their exposure to air pollutants found in indoor air could potentially be as, or indeed more, significant than exposure to pollutants found in outdoor air that might typically be experienced on the average person’s commute to work.

While levels of external air pollution inevitably influence the indoor air quality within a building, it will depend on various other building design, construction, operation and maintenance factors including:

  • Ventilation strategy including the location of openable windows and air intakes.
  • Airtightness of the building fabric, i.e. how ‘leaky’ the building is in allowing the ingress and egress of air pollutants.
  • Internal sources of air pollutants such as combustion appliances, construction materials, and furnishings, cleaning products, etc.
  • Cleanliness of the building and ventilation system components.

In terms of achieving acceptable levels of indoor air quality, source control through eliminating or minimizing sources of non-human pollutants should be the primary strategy, e.g. careful selection of low emission building materials and furnishings. However, in most buildings it will be impossible to eliminate all potential non-human pollutants, so ventilation will be required to control both human pollutants (e.g. exhaled carbon dioxide, body odor, etc.) and any pollutants left after source control. Finally, if ventilation cannot dilute or disperse all pollutant sources, it may be necessary to use air cleaning methods such as filtration (e.g. particulate filters in outdoor air intakes).

Day-to-day assessment of indoor air quality in operational buildings has traditionally relied upon monitoring and managing the level of carbon dioxide (CO2) in occupied spaces, especially as ‘real-time’ CO2 sensors are a well established and affordable technology, with the control of CO2 levels being used as a proxy for the control of other potential pollutants. In terms of commercial real-time sensors for other pollutants for use in buildings, while these are available, these tend to be quite expensive and are not routinely employed for day-to-day building management purposes.

The last few years have seen an explosion in the number of devices, sensors, and apps on the market targeted at consumers that claim to measure or monitor air quality related parameters in real-time. It is important to note that the market for these consumer-targeted air quality monitoring products is currently viewed as a bit of a ‘wild west’ due to the absence of any widely accepted standards or testing protocols that a product’s performance (e.g. accuracy, precision, and reliability) can be verified against. While efforts are underway to develop standards and testing protocols for these products, in the interim it would seem sensible for building owners and managers to treat any outputs from such devices with caution, e.g. as a basic indicator of indoor air quality that may prompt further investigation. However, these products are widely available and are potential sources of data for building occupants to make their own assessments of the quality of indoor air within a space. This could potentially lead to an increasing number of complaints or concerns about indoor air quality being raised with building owners and managers by building users based on the outputs from these products.

Given the growing awareness of air pollution and indoor air quality issues, it seems likely that there will be an increasing demand for building owners and managers to demonstrate that their assets are designed and operated to deliver good indoor air quality, including how they are performing in real-time. Whilst robust, quantitative and affordable real-time measurement of all potential indoor pollutants is probably not feasible for most buildings at this moment in time, building owners and managers can still highlight the indoor air quality-related features and strategies that have been implemented in a building’s design, as well as the operational procedures in place that are helping to maintain good indoor air quality.

Design and operational related indoor air quality performance requirements have been key components of several green building certification schemes, including BREEAM, for many years. Therefore, third party certification to green building standards can be valuable evidence to demonstrate how an asset is delivering good indoor air quality.

This article was written by Christopher Ward, BREEAM Principal Consultant at BRE

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