Popping indoors for a breath of fresh air!

Popping indoors for a breath of fresh air!

Worried about air pollution? Are you safe indoors? Probably not. Sadly, the place where we spend 90% of our lives could be more dangerous than the great outdoors. But, with careful design, planning, and an understanding of how modern buildings ‘work’, it does not have to be that way.

I would like to show how the old relationship between outdoor and indoor air is changing and why, even when we keep ‘dirty’ outside air at bay in air-tight buildings, ‘the enemy within’ has us trapped.

I also want to examine ways in which we can manage and design out this complex problem, and ask if buildings themselves could evolve in the light of our Covid experiences.

Finally, I thought it would be helpful to list both some obvious and surprising pollutants now found in homes and offices, and steps we can take to avoid using them.

Inside out

Up to now, planning and environmental permitting applications have had to assume that pollution measured on the outer surfaces of buildings – their facades – is a reasonable proxy for airborne risks occupiers face inside.

Pandemic lockdowns and airborne infectionThis limited appreciation of indoor risks is changing rapidly. Pandemic lockdowns and airborne infection worries have seen us spending more time between four walls … and focussing more closely on what we take in through our nostrils.

The unsettling answer is that indoor air quality may now have a greater impact on our health as we breathe in a wider range of pollutants in higher concentrations for longer periods.


One of the new mantras during the pandemic has been to provide more and better ‘ventilation’.

three pathways through which outside air can pollute inside airThere are three pathways through which outside air can pollute inside air. The first – natural ventilation through gaps, cracks, windows and doors – has the side-effect of letting polluted external air flow indoors unaided. The gradual infiltration of air into ‘leaky’ buildings does the same.

However, we are now encouraged to make buildings draft-proof to save energy and carbon, so cutting off the positive advantages of fresh air.

The answer in many cases is mechanical ventilation which artificially forces air through properties.

If it draws in unfiltered outdoor air, we are back to square one. But with filters, or a closed-loop internal cleaning and recycling system, the external air pollution problem can be eliminated. The caveat, as the pandemic has shown, is that air flows are sufficiently large.

Deep breaths

But there are now additional indoor problems where, especially in airtight properties, more sophisticated solutions are needed to safeguard health and safety.

chemicals and toxic substancesThe continued use of chemicals and toxic substances in ordinary households and ‘sealed’ buildings is potentially making the indoor environment more dangerous than outdoors.

Good mechanical ventilation systems can help to solve this. Meanwhile, consciously avoiding specific materials, and adjusting maintenance and cleaning routines, is also important.

This is where Enzygo (https://enzygo.com/) can help.

Designing effective layouts and ventilation systems at the beginning of all projects to meet rigorous indoor and outdoor standards before mistakes become embedded is now important.

However, whilst mechanical ventilation is the interim solution, I believe that the opportunity for natural ventilation through open windows is the ultimate goal.

That brings us back to solving outdoor air quality, which is a priority for the team that I am now privileged to lead.

Designing out risks before they become problems

When I began my career in the air quality industry more than 25-years ago, the expectation was that chronic problems could be resolved by now. Instead, they have become worse, partly because we now understand the dangerous chemistry of air pollution and its negative health impacts, but also because of growing indoor risks. (See ‘Fresh air – the growing battle to end airborne pollution – https://enzygo.com/fresh-air-the-growing-battle-to-end-airborne-pollution/).

As a multi-disciplinary environmental consultancy specialising in design, planning and permitting issues, Enzygo and its air quality service brings together the skills needed to tackle increasingly complex problems (https://enzygo.com/services/air-quality/).

In this role, we provide source-pathway-receiver assessments at the design stage, plus BREEAM ratings assessments for building materials.

We also advise on the use of heating, ventilation and air-conditioning (HVAC) systems, supervise indoor air monitoring post-construction, and ensure that guidelines and a high standard of build are always met.

HSE ventilation advice during the pandemic

The Health and Safety Executive (HSE) is also a source of regularly updated best practice advice and regulation. It points out that the law stipulates employers must ensure there is an adequate supply of fresh air (ventilation) in enclosed workplace areas.

It offers guidance (https://www.hse.gov.uk/coronavirus/equipment-and-machinery/air-conditioning-and-ventilation/index.htm) to help employers and employees: – assess workplaces to identify poorly ventilated areas (https://www.hse.gov.uk/coronavirus/equipment-and-machinery/air-conditioning-and-ventilation/identifying-poorly-ventilated-areas.htm); and decide actions to improve ventilation (https://www.hse.gov.uk/coronavirus/equipment-and-machinery/air-conditioning-and-ventilation/how-to-improve-poor-ventilation.htm).

Redesigning the indoor environment

How did we get into this pollution nightmare in the first place, and how do we get out of it? The pandemic, perhaps ironically, may have done us a favour.

It could lead to the biggest overhaul of urban planning for public health in almost 200 years, with scientists suggesting that governments must embed better ventilation into the planning code for public buildings to prevent the aerosol spread of diseases in crowded indoor spaces.

The precedent they point to is London’s 1842 cholera epidemic when Edwin Chadwick secured clean water supplies, improved drainage systems, and a ruling that councils must clear refuse from homes and streets – these are changes that have inspired hygiene codes in cities around the world.

It is easy to think of 19th century Londoners as naïve for believing that a miasma (smell or vapour) caused cholera, when in fact the health risk from today’s indoor spread of invisible airborne pathogens is of the same magnitude.

In the developing world, a major source of indoor air pollution is burning coal and biomass – wood, charcoal, dung, or crop residue. Unfortunately, high particulate concentrations were linked to between 1.5 million and 2 million deaths in 2000.

Interestingly, there is pressure to outlaw wood-burning stoves in modern London.


Part of the problem may be that it is easier to track down a single water pipe or package of food as the cause of trouble than a hidden virus. For decades building designers have also focused on keeping people at a comfortable temperature and saving energy.

Another long-debate has been about the definition of ‘acceptable’ indoor air quality. One consideration is how often indoor air is replaced with outside air. Classrooms must have 2.5 outdoor air changes per hour. Carbon dioxide in halls, gym, dining, and exercise spaces, should be limited to 1,500 ppm.

Effects on human health

Poor indoor air quality has also been linked to sick building syndrome, lower productivity, and impaired learning in schools.

An Imperial College study is currently exploring how indoor air pollution affects human health (https://www.imperial.ac.uk/news/227153/new-study-explores-pollution-indoor-spaces/).

In a series of four-year projects in West London, environmental, social, medical, engineering, economic, scientific, and local health community experts are working together to investigate how the composition, concentration, and exposure to air pollutants affects children with asthma and people in urban homes and workplaces.

Threats that lurk in offices and homes

While many of the key sources of indoor air pollution in the UK need to be considered at the design stage, there are simple steps that most people can take to reduce direct health risks in their own homes or offices.

They include avoiding the use of: –

Volatile organic compounds (VOCs) – These are chemicals found in many materials in the home which evaporate into the air at room temperature as vapours we can inhale.

High risk substances include benzene from petrol, cigarette smoke, paints and solvents. Low risk examples are terpenes that include limonene and pinene which give cleaning products their lemon and pine smells.

Some VOCS, and especially terpenes, can combine with ozone in hot weather to form gases that include formaldehyde which is a lung irritant, and at very high levels carcinogenic.

Alternatives – Opt for unscented or allergy-friendly products. Use easily-inhaled aerosols and sprays only sparingly. Use water-based rather than solvent-based paints, dust with a damp cloth or electrostatically charged duster, and remove the causes of smells instead of using air fresheners.

Particulate matter – These are minute particles that can enter lungs and create serious health problems.

They generally come from combustion processes like cooking, smoking, electric toasters, candles, wood-burning stoves, and open fires, but also vacuuming and dusting. High levels can inflame airways, exacerbate heart and lung diseases, and shorten lives.

extractor fansAlternatives – Remedies include using extractor fans, cooker hoods, and opening windows or trickle vents. Regular vacuuming controls airborne particles, preferable with a machine that puts minimum emissions back into the air. HEPA filters can help with allergies.

Wood-burning stoves should only use untreated dried wood with dampers wide open and regular flue cleaning; wood smoke is a major source of urban air pollution.

Carbon dioxide (CO2) and carbon monoxide (CO) – Are released from appliances that burn fuel, such as open fires and gas cookers.

CO is particularly dangerous when carbon fuels are burned with insufficient oxygen in poorly-maintained gas boiler and heaters, plus portable gas and paraffin heaters with no flues. CO2 can cause drowsiness, dizziness and headaches. Detectors are essential.

Alternatives – The advice is not to use unvented appliance, service and maintain cookers and heaters with flues regularly, and ventilate bedrooms to avoid CO2 and moisture build-up.

Other pollutants – Can include radon, nitrogen dioxide (NO2), water vapour from condensation, bacteria, mould, fungus spores, dust-mites, and flecks of pet skin or fur (dander).

Radon is a carcinogenic radioactive gas released naturally by uranium in soil and rocks. In most parts of the UK levels and risks are low.

NO2 is generated by combustion. Indoor levels are often higher than outside. They can increase the effects of allergens like dust-mites, and irritate the eyes, nose, throat and respiratory tract.

Water vapour from cooking and washing and drying clothes encourages microbiological growth. Dampness and mould can create serious health problems.

Alternatives – A series of measures can be taken to eliminate each source.

Bespoke solutions

If you would like to discuss any of the points made above, or specific projects, or general air quality problems confidentially, please contact me directly.

Conal Kearney, Director of Air Quality ([email protected]).

Conal has extensive air quality industry experience in the public sector – including the Environment Agency and local government – and private sector in consultancy roles.

As a Member of the Institute of Air Quality Management and Institute of Environmental Science, he has provided detailed air pollution impact assessments, odour impact assessments, local air quality management, and air quality monitoring projects.

He has also worked in a wide range of development projects, from major residential schemes to commercial and industrial developments in the energy, waste and minerals sectors.

In addition, Conal has provided air quality project directorship in large Environmental Impact Assessments for planning and Environmental Permit applications, plus expert witness services.

See the LinkedIn article – https://www.linkedin.com/pulse/popping-indoors-breath-fresh-air-enzygo-limited/

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