Beating airborne pollution at home

Healthy indoor air can be compromised by particulate matter and volatile organic compounds. Rachel Rose explains what they are and how to minimise their impact.

Modern humans are a largely indoor species, spending as much as 90 per cent of our time inside. Kids are spending more time indoors (whether at home, daycare or school) than previous generations, and people spend more time indoors as they age. The quality of the indoor air we’re breathing matters more than ever.

We’re limited in how much we can influence the indoor air quality (IAQ) in workplaces, shops, theatres, hospitals and schools. But there is a lot we can do to ensure better IAQ in our homes. Some of the biggest improvements come from not doing: stopping those things that degrade air quality.

In ‘A breath of fresh air’ in Sanctuary 74 we looked at the value of carbon dioxide (CO2) monitors, which can help us understand whether our homes are sufficiently ventilated. This issue we dive into other aspects of IAQ, notably particulate matter (PM) and volatile organic compounds (VOCs): what they are, how they affect health and how to minimise their impact.

The air quality baddies

Volatile organic compounds
VOCs are chemicals that vaporise at room temperature. They come from both products and processes. Some have names we might recognise, like formaldehyde and benzene, but the list of VOC-producers is long. It includes materials used to build and finish homes as well as everyday products and activities. (Not all are bad! There are biogenic volatile organic compounds (BVOCs) like terpene, released by trees and responsible for some of the benefits of forest bathing. But this article is focused on the problematic human-created chemicals.)

The health impacts of VOCs are well established. The main risk is to the respiratory system, causing eye, nose and throat irritation, plus dizziness and headaches. They can trigger allergies and asthma attacks or cause skin irritation. Phthalates are semi-volatile organic compounds that are known endocrine disruptors, creating longer-term impacts. VOCs can damage the central nervous system and other organs, and some can cause cancer.

We can’t see VOCs but some we can definitely smell: think of that ‘new car’ smell, freshly laid vinyl flooring or new paint, a new foam mattress or anything made of polyvinyl chloride (PVC). Human noses aren’t failsafe detectors though, as some VOCs are odourless.

Particulate matter
Particulate matter refers to solid material – such as specks of dirt, dust, soot and black carbon – in the air around us. The particles are too small to see with the eye, although when they’re highly concentrated the air becomes hazy, as with bushfire smoke. PM is defined by its size, not material. PM10 is 10 micrometres (µm) or less in diameter; for comparison, a human hair is around 100µm. Fine particulate matter – PM2.5 and smaller – is of special concern for air quality and health. Official government advice about exposure to fine PM is sobering: there is no threshold at which health effects do not occur.

The finer the particulate, the greater the health risk, and these risks increase with continued exposure. The smallest particles penetrate deep into the lungs and can enter the bloodstream, potentially causing serious problems for the lungs and heart. As with VOCs, people who are already medically vulnerable are especially at risk.

PM pollution is an issue indoors and out. Outdoors, it can come from bushfire smoke, industrial pollution and vehicle fumes. Inside, the biggest contributor is from combustion: wood fires, gas appliances, and even candles (especially scented ones) and incense. These latter give off a complex mix of chemicals and particulate matter, including toxic gases like carbon monoxide, sulphur dioxide and oxides of nitrogen.

What can you do?

Reduce
There’s a lot you can do to cut down on the nasties in your indoor environment. Add VOC levels to your assessment criteria for flooring, furniture and finishes. Be aware that researching materials and sifting through greenwashing can be time-consuming. The International Living Future Institute’s Declare database (bit.ly/DeclareAUNZ) is a helpful shortcut to hours of research. It lists products that are free of the Red List chemicals that are unacceptable in buildings seeking certification under the stringent Living Building Challenge standard.

Consider the glues in laminated products, including plywood. Chemicals can hide in natural fibre products: consider the underlay beneath your wool carpet, or the insecticides it is likely impregnated with to repel carpet moths. Curtain and upholstery fabric billed as ‘stain-resistant’ may have been treated with harmful ‘forever’ chemicals, but it’s possible to find alternatives with diligent research.

Banish all types of smokers to the deck or back of the garden. Everyone understands the dangers of secondhand tobacco smoke, but vapes also emit a cocktail of chemicals, VOCs and PM. The other smoker to avoid is your petrol or diesel car’s exhaust. Garages with direct access to the house are significant household polluters. These cars continue to emit fumes after they are turned off, so ideally leave the vehicle outside or leave the garage door open until the engine is cool, and ensure the door between the garage and the house is airtight. (This is vastly less of an issue with full electric vehicles, which emit no exhaust.)

It’s well known that open fireplaces and woodburners produce outdoor air pollution, which is why their use is regulated in some states. This polluted outdoor air can enter the home (yours and your neighbours’) when ventilating. But indoor air quality is also directly impacted when lighting the fire and refuelling. This applies to cleaner-burning, certified models too. Particulate matter going up the chimney can settle on rooftops, which is bad news for homes collecting rainwater off the roof.

Beds and bedding deserve special consideration given the amount of time we spend sleeping. Modern mattresses typically contain many different materials. Beware of greenwashing: a mattress might boast an organic cotton cover, but what’s inside? Ask about all the materials, not just the ones the marketers want to highlight. Foam is of many different types and is generally a big VOC source. Better options are solid latex or cotton/wool futon-style mattresses; both come in different levels of firmness. For pillows, avoid polyester and opt for natural fibre fill. There are lots of options: wool, cotton batting, latex chips, buckwheat hulls and feathers.

Dilute
The second solution brings us back to ventilation and the need for constant, adequate air exchange. Get yourself a CO2 monitor, as a healthy CO2 level is a reasonable proxy for IAQ more generally. If ventilation is adequate to keep CO2 below 800ppm, VOCs and PM will be diluted as well.

Airing specific items outside is a simple and effective solution. So if, for instance, waterproof mattress protectors (usually made from PVC) are a household essential, wash thoroughly and hang up to air outside for a few days before first use.

If you’re not sure of your new mattress’ credentials, remove the plastic wrapping and leave it in the garage for a while; the intensity of VOC offgassing will reduce over a week. Ventilate your bedroom especially well for the first weeks of use indoors.

If you can’t part from favourite clothes that require drycleaning, remove the plastic wrapping and air thoroughly outside before bringing them into the house.

Both strategies – reducing and diluting – can significantly improve the quality of the air inside our homes. However, ventilating is a solution only when the outdoor air is clean. When it isn’t, HEPA units with carbon filters are a good, simple option for many people; continuous mechanical ventilation with filters is the gold standard solution, and comes with the added reassurance of being able to swap to higher grade filtration in emergencies, such as when bushfire smoke is making the outdoor air dangerous to breathe.

In summary

We need overlapping solutions to ensure we’re all breathing better air: let’s do what we can in our own homes, and support all efforts to reduce outdoor air pollution, achieve greenhouse gas emission targets and regulate for improved IAQ in public indoor spaces (especially schools and hospitals). Skilful conversations with family, friends, workmates and neighbours about our own choices and experience also shift collective thinking, one conversation at a time.