Indoor air pollution: what causes it and how to fight it

We’re all aware of the dangers of air pollution – tending to think of it as a symptom of industrial traffic-clogged cities. Images of hazy urban smog and billowing plumes from factories spring to mind. But in some cases, your house could actually have worse quality air than out on the street.

indoor air pollution, koru architects, eco architects

Beijing city smog – what most people initially think of as ‘air pollution’. Photo by Ilya Haykinson (Creative Commons).

Policy and attention has rightly focused on outdoor air pollution from traffic and industry because that is generally the biggest risk. The majority of the 40,000 early deaths caused by air pollution in the UK each year are due to these sources.

However, experts now say we have overlooked indoor air pollution and it needs more attention. Europeans now spend on average 90% of their time indoors so the quality of air in our homes, schools and workplaces is crucial to health. Children, the elderly and those with existing illnesses (especially asthma) are most at risk, but even healthy, non-vulnerable people could suffer from chronic effects from long-term low-level exposure that builds up over their lifetime.

We don’t even have enough evidence to know all the long-term and combined effects of indoor pollutants.

Of course, you want to feel safe and protected in your own home, and more than anything want assurance that your children’s health is protected. This post outlines the major risks from indoor air pollution and suggests behavioural and design solutions.

What causes indoor air pollution?

Some of the common pollutants found inside homes are:

  • tobacco smoke
  • particulate matter
  • carbon monoxide (CO)
  • nitrogen dioxide (NO2)
  • volatile organic compounds (VOCs)
  • radon
  • lead
  • biological allergens including mould, dust mites, pollen and pet dander (biological allergens are irritants for people with asthma, hayfever and other respiratory problems, while the others are harmful for everyone)
indoor air pollution, koru architects, eco architects

Many paints release VOCs. Choose non-toxic natural paints for better indoor air quality. (Public Domain Pictures).

By far the biggest causes of poor air quality in the home are lack of ventilation and smoking indoors.

However other causes include outside pollutants coming into the house via windows and shoes (particulate matter, NO2, pollen), unserviced cooking/heating appliances (CO and VOCs), bathroom condensation (mould), paints and varnishes (VOCs), cleaning products and aerosol toiletries (VOCs, particulate matter), pets (dander), open fires (particulate matter) and drying laundry indoors (mould and dust mites).

Most of these would not be very problematic with good ventilation, but they exacerbate each other.

And what are the effects of indoor air pollution?

A 2010 government report lists health impacts of the most common indoor pollutants. NO2, particulate matter and VOCs are linked to respiratory illnesses.

Particulate matter also increases risk of heart disease. Second-hand tobacco smoke, as you’ll surely know, is a major cause of lung cancer and respiratory problems. The gas radon (which comes from decomposing uranium in the soil and enters the house via the foundations) increases risk of lung cancer in high concentrations but at low levels isn’t a major problem. CO can be lethal in high concentrations, and early research suggests it could have chronic impacts at low-levels as well.

According to My Health My Home, poor air quality at home can also lead to milder effects like coughing, sneezing, watering eyes, headaches and fatigue.

So, that all sounds pretty horrible. What can I about it?

There are many behavioural changes and precautions you can take to make sure your indoor air quality is up to scratch.

  • Install a mechanical ventilation system. If your home is newly built you’ll probably already have one, but if you don’t you can get one installed to ensure good ventilation. One with heat recovery is the best choice for energy efficiency.
  • Get a CO (carbon monoxide) alarm and have your boiler and gas cooker checked regularly by a registered Gas Safe engineer.
  • Don’t smoke inside.
  • Get a radon test.
  • Get people to take off their shoes by the door.
  • Use eco-friendly cleaning products and avoid aerosols and air fresheners. Air fresheners and other household products can contain a potent cocktail of potentially harmful chemicals under the opaque label ‘fragrance’ without needing to list each individual ingredient.
  • Use eco-friendly paints, varnishes and furniture polish.
  • Use an extractor fan or open the window when cooking or taking a shower.
  • Dry laundry outside when possible.
  • Choose wooden floors rather than carpets, which harbour dust and spores – or at least vacuum carpets frequently.
  • Get some house plants. They purify the air by absorbing pollutants and releasing oxygen.

    indoor air pollution, koru architects, eco architects

    Forget chemical laden air fresheners – plants naturally clean the air. Photo by F. D. Richards (Creative Commons).

In addition to these everyday actions, it’s important to consider air quality when designing an extension, a major refurbishment or even a new house.

We always take care to keep these points in mind for all our projects, and you should too if you’re planning any building works.

Koru’s tips for better air quality

  • Use natural materials for construction and insulation. Materials like timber, stone, zinc, slate, glass, hemp and sheep’s wool are naturally non-toxic, while plastics and other petroleum or chemical based artificial materials can off-gas at low but still unhealthy levels.
  • Use natural paints and varnishes for finishing the inside of habitable rooms.
  • Completely avoid highly toxic materials like lead and asbestos and also lesser toxins like PVC.
  • Ensure the building fabric is highly air-tight.
  • Always install a mechanical ventilation system with heat recovery.

The future?

There’s no one government department with sole responsibility for regulating indoor air quality, with fragmented efforts to limit certain toxins and ensure ventilation being spread across local councils, DEFRA and the health department.

For example it is required by building regulations that habitable rooms must have some form of ventilation. This is enforced for new builds but older properties are not always kept up to the recommended standard. The EU directive on air quality and most national legislation is focussed purely on outside air quality.

As the BBC reports, experts are now calling for more research into the quality of indoor air. In the meantime it is up to homeowners and designers to ensure homes are built and maintained with health in mind.


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