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Factors that affect Indoor Air Quality

7th April 2022

As humans, we eat around 2kg of food and fluids per day, but we breathe in and exhale approximately 13kg of air each day. Even though we are aware of the effects of pollution outdoors, we typically pay less attention to the quality of our air indoors. With the average person spending 90% of their life indoors, Indoor Air Quality deserves to be talked about.

In this Knowledge Hub piece we explain the following;

  • Types of pollution
  • The advantages and disadvantages of both natural and mechanical ventilation
  • The opportunities and obstacles

Types of Pollution

There are a wide range of contaminants that we produce in our own homes. Whether we can see the particles or not, there are activities we do every day which contribute to poor Indoor Air Quality and have potential to cause us health problems including asthma, bronchitis, breathing and lung issues and inflammation of the nose and throat.
One sub-section of contaminants is defined as particulates. Particulates in the air can vary in size; some can be seen, and some are too small to see. Particulates which can typically be found in the office include residue from cleaning and fibres from clothing and soft furnishings. There are also particulates caused by exhaling and these increase with physical activity.
Another sub-section of contaminants includes Volatile Organic Compounds (VOCs). Nitrogen dioxide caused by passing vehicle traffic may also enter the home through open doors and windows, posing a risk to Indoor Air Quality.

Natural Vs Mechanical

One decision to make straight away is whether to increase ventilation naturally, i.e through opening doors and windows, or whether to increase ventilation mechanically through the use of fresh air supply systems and air handling units (AHUs).
There are advantages to each solution.

Natural Ventilation Advantages and Disadvantages

Advantages of natural ventilation
– Providing ventilation via natural means is considerably cheaper than investing in a mechanical solution.
– If the workspace is temporary of infrequently occupied, or if the occupants plan on moving premises in the near future, it may be a better option to provide open doors and windows as ventilation in the short term since this will cost less.
Disadvantages of natural ventilation
– It is not possible to always provide a consistent level of ventilation through open windows. External factors including wind direction and wind speed make the job of ensuring the indoor space is always comfortable somewhat difficult.
– End-users are familiar with the operation of doors and windows. Whilst it is intended the windows are kept open to provide optimal ventilation in the area, individuals may close the windows or doors if they feel cold or feel a draught.
– There may be detrimental consequences to IAQ caused by opening windows, especially when the outside ambient air is poor (if there is a busy road with lots of vehicle fumes, for example).

Mechanical Ventilation Advantages and Disadvantages

Advantages of mechanical ventilation
– For optimal results from ventilation, it is essential that there are consistent air changes in the room. Consistent air changes can only be achieved with a mechanical system.
– If the outdoor pollution level is high and opening windows is not possible, then mechanical ventilation is a viable option for making the workspace safe whilst providing adequate fresh air.
– Ventilation systems are paramount in sealed rooms, including clean rooms where there can be no contaminants in the room. In these cases, mechancial ventilation is the only option.
Disadvantages of mechanical ventilation
– The positioning of Air Handling Units for drawing in the fresh air needs to be considered. It is important that the AHU is positioned away from any fumes or other sources of poor IAQ which could be drawn into the mechancial ventilation system resulting in a smelly and possibly unhealthy working environment.
– The outright capital expenditure and cost of routine maintenance is a big consideration. Routine maintenance cannot be skipped; it is important that the system continues to offer good circulation and the pest guards and filters are inspected frequently and replaced as required to ensure optimal performance of the ventilation system.
– Ventilation systems are designed with the room’s use in mind. A change in the use of the room i.e. addition of lots of machinery in the room or addition of lots more occupants, may result in the existing ventilation system being no longer satisfactory.

The Opportunity

The COVID-19 pandemic has propelled the importance of IAQ into the spotlight, both within the mainstream media and amongst industry professionals.

Business owners are understanding the importance of good IAQ in their workplaces and are therefore becoming increasingly interested in mechanical ventilation.

Within the industry, we see this as positive news albeit with slight trepidation. Indeed, it is good news that businesses are more aware of how ventilation can have a positive impact on their indoor workspaces. However, it is crucial that they acknowledge the importance of needing, not only ventilation, but good ventilation, and ventilation that delivers on providing the adequate fresh air they require.

It is fundamentally important for end-users to understand the basic principles behind it and to give due care and attention during the design phases.

Silver Lining

The COVID-19 pandemic has led to a rise in homeworking across many sectors. As a result, fewer employees are travelling to the office to work. Lower occupancy rates in offices have meant a ventilation solution, pre-pandemic, which was struggling to deliver on the necessary rate of air changes to, now becoming an optimal solution based on the quantity of employees in the space nowadays.

The Obstacles

Whilst we all recognise the importance of having good clean air around us, the exact measure of what is defined as safe is hard to define.

The World Health Organisation (WHO) have identified particulate matter as being the most damaging to health due to their ability to enter the lungs and into the bloodstream and other organs. Particulates ae categorised by size, which indicate their influence they can have on the human body. There is still more research to be done to determine exactly what the risks are associated with these smallest types of particulate matter, with 25 micrograms per meter cubed of air, or PM 2.5 or below.

Measuring precise levels of contaminants indoors is also troublesome and the monitoring equipment is expensive. Environmental audits can indicate whether a workspace is free of harmful pollutants but the audit results are only valid during the time the audit takes place. The following day, there are many factors which may impact the number of VOC’s or particulates in a room, causing a spike in readings hence rendering the results of the audit invalid.

There are other crucial updates happening in areas of building safety, particularly in relation to fire safety and fire suppression and the greater need for sealed buildings and contained rooms, which are impacting on a building’s capability to provide natural ventilation. As buildings increase their ability to suppress fires, they inherently are unable to bring in and circulate fresh air. As a result, we may experience an increase in the demand for mechanical ventilation especially in new buildings.

Final Words

Indoor Air Quality is an important subject which has been magnified since the COVID-19 pandemic. The industry, manufacturers and health professionals all agree that IAQ is vital in safeguarding our population’s health and well-being.

We know IAQ is difficult to measure and define safe levels for, but it is true that people are the best monitors. We as humans have an ability to identify bad smells, or cool draughts. The best air conditioning or ventilation systems are the ones we do not know are there, they just do their job.

In the future, we would like to see more inexpensive measuring devices and better guidance for determining what are safe levels of particulates and other contaminants in a space, based on the room’s function.

For now, we can all act individually, but collectively, to each do our bit to support the cause and boost indoor air quality in our homes, schools, workspaces, and leisure spaces.

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