The Ins and Outs of Air Pollution

The Ins and Outs of Air Pollution

By Paul Williams, Domus Ventilation Product Manager

Air pollution is well and truly headline news, but are we in danger of missing the elephant in the room?  We spend 80-90% of our time indoors and whilst we are at risk of polluted external air entering our homes, that’s not the full story.  By focussing on external air pollution, are we in danger of side-lining indoor air pollution?

What are the indoor pollutants?

When it comes to outdoor air pollutants the focus is very much on NO² and PM2.5, with the key emissions sources being transport and domestic fossil fuel burning respectively.  For those living near busy roads and in built up areas, these emissions remain a problem indoors as well as outdoors as they readily enter homes around closed doors, through windows etc.

In some cases, these and other harmful gases, such as carbon monoxide and sulphur dioxide, are found in greater concentrations indoors than they are outside due to a lack of ventilation.

But pollution is also generated by activities conducted within the house.  Levels of particulate matter (PM) increase burning fossil fuel such as gas cookers and heaters, and even candles.  The cleaning equipment used often contains harmful toxins that accumulate indoors and linger. Even seemingly innocuous items within homes, such as furniture and the very materials these homes are built from, can release potentially harmful pollutants if properties are poorly heated and ventilated.

Sadly, this is a much under studied area and our knowledge of the sources and worst effects of indoor air pollution is lacking.

How to address indoor pollutants

Whilst ‘there are things that we know we don’t know’, as the saying goes, the things we do know that cause potentially harmful pollutants indoors we can address.

The first and easiest one of these is to switch to non-toxic cleaning products.  It’s a simple one that everyone can do and is good for us and good for the environment and there’s plenty of them to choose from.

The second is to move away from fossil fuels in our home. For most, that means moving to electric, although obviously there are other heating solutions such as heat pumps, solar etc.

Whilst the first two focus on removing the pollutant at source, the third way to address pollutants in our homes is to disperse them through effective ventilation. The simplest form of ventilation is to open windows, but this isn’t a good option if the property is in a heavily polluted area as you are simply bringing more polluted air into it.  Basic mechanical ventilation, such as bathroom and kitchen fans are essential and will remove a level of pollution (as long as they are correctly ducted!), but to truly make a difference you need to turn to mechanical ventilation systems.  And this is where housebuilders can make a potentially life changing difference to future home owners and residents.

The Ins and Outs of Air Pollution

Effective ventilation = mechanical ventilation

Mechanical ventilation, in the form of intermittent extract, continuous extract or supply & extract, are recognised as the most proficient means of ventilating a modern property.

Mechanical Extract Ventilation (MEV) and Mechanical Ventilation with Heat Recovery (MVHR) systems actively extract air from wet rooms (kitchens, bathrooms, utility spaces) via ducting to a central ventilation unit which exhausts to the atmosphere.  In the case of MVHR, there’s the added benefit of supply and extract ventilation combined as these systems re-use waste heat from the extract air and use it to efficiently pre-warm the fresh air drawn into the building using a heat exchanger.  The filtered, pre-warmed air is then distributed around the home, effectively meeting part of the heating load in energy efficient dwellings.  Domus Ventilation’s HRXE MVHR units feature advanced heat exchange proficiency enabling up to 95% of waste heat to be recovered.  They come with 100% thermal (summer) bypass which automatically activates when the air temperature reaches a pre-set level, allowing in cooler, fresh, filtered air without warming it through the heat exchanger.

Both MEV and MVHR systems provide effective ventilation, are energy efficient and extremely effective at dispersing polluted air.

The Ins and Outs of Air Pollution

Even with these clever systems, they still rely on brining outdoor air in so, in more polluted areas such as cities – you will need to combine them with a filter.  The Domus Ventilation NOX-FILT, for example, works on the supply leg of the ducting system of a mechanical ventilation system and prevents up to 99.5% of NO² pollution from entering a home.  There are two units in the range with the second one having the added benefit of a PM2.5 pre-filter.

Because of the nature of these systems, which require extensive ducting, they are mostly suited to new build properties.  For existing properties, the most cost-effective options are bathroom and kitchen intermittent extraction fans (Axial and Centrifugal) and Positive Input Ventilation units (PIV).  PIV units are a cost-effective method of eliminating moisture from the home by gently pressurising a dwelling to expel stale and humid air through natural ventilation points.  They can be mounted either in the loft area of a house, or a hallway cupboard of a flat.

Getting to grips with indoor air quality

We certainly don’t want to detract from the work being done to improve external air quality – it’s literally life saving – but we do need to start taking indoor air quality seriously.  We should feel safe in our homes.

Domus Ventilation is a manufacturer of market-leading ventilation systems that save energy and improve indoor air quality.