Air pollution: A five minute primer

A quick primer on the pollution accelerated by our recent Australian bushfires, how to keep yourself up to date on health risks and how you can reduce harmful particles in the air you and your family breathe.

By Dr Marc Theilhaber, Respiratory Paediatrician

Table of contents


Avoid falling for snake oil

Keeping yourself informed

Useful web sites and apps

Protecting yourself

Inside your home



It’s a sad reality that we will have to deal with significant air pollution in our cities and towns for the foreseeable future. The general health advice is to limit exertion and outdoor exposure during periods of severe air pollution. In reality we won’t be able to put life on hold. However, children will still need to go to school, adults will need to go to work – our world and lives will need to keep on moving even with significant shifts in our environment. But we will need to get smarter about how and when we do certain things.

As with many things in life, information is key. We are all used to listening to the weather report when planning our activities for the next day. As awkward as this may sound, we may well need to incorporate the pollution report for the next day and week into our activity planning. Picnic at the beach this Sunday? Well, while it might well be going to be sunny the air quality index could also be predicted to be very high (which means: poor), so maybe invite people over for some indoor activities. What sounds weird right now may quickly become second nature. Just think back to how unusual people wearing Apple’s AirPods looked with those ‘feet’ sticking out of the ears when today no one bats an eyelid about people wearing this ear phones anymore.

We will aim to keep an updated list of tools here for you to help you through your day. How to easily stay updated and informed on the level of air pollution. Where to get aids to potentially reduce indoor particle levels or masks to reduce particle load in your inspired air when going outside.

If you’d like to get a whiff of how it feels having to deal with severe pollution every day of your life, head over to Richard Burrow’s site. Richard is a Thailand based school teacher and avid blogger and has reviewed many air pollution monitors out of sheer necessity. His reading makes for a sobering wake up call.

Don’t fall victim to those that prey on your concerns

Please be aware that particularly in times of anxiety some unscrupulous snake oil vendors will try to monetise on people’s fears and sell you bogus things for lots of money. This may be through selling devices with alleged magical air cleaning powers, face masks that miraculously will filter all dangerous particles through ‘exclusive’ technology (even or ‘specifically’ for children) or peddle easy to take ‘vitamins’ or ‘supplements’ that are supposed to strengthen your body against the ill effects of smoke pollution. We strongly encourage you to do your own research before you buy any of these. It’s worth keeping in mind the old adage: ‘If it sounds too good to be true, it probably is.’

Keeping yourself informed

Official information on air quality from the Environmental Protection Agency Victoria.

This site gives a good overview and forecast on air quality in Victoria. Ideally used on a desktop computer to get an overview or do forward planning. Multiple measure go into assessing air quality, there’s a short primer on Australia’s air quality standards on the website of the Australian Department of Environment and Energy.

Up to date pollution notifications on the go with Airrater.

This Australian made applications has gathered wide interest over recent weeks. Developed with support from multiple Australian research organisations, AirRater was originally aimed at aiding those suffering from asthma and similar respiratory conditions to alert them to hazardous weather and pollution situations. The recent horrific bushfire situation has made Air Rater an app that is useful for everyone in Australia – chronic health condition or not.

Define multiple geographic trigger zones such as ‘home’ or ‘work’ and Air Rater will alert you to hazardous pollution levels – even if the app isn’t running. You can also track your own health symptoms with this app and see how these correlate with environmental conditions to help identify what triggers you are particularly sensitive to. The app is free to download and use.

Download on the App Store | Download on Google Play

Airvisual Air Quality Forecast

Another option for air quality monitoring on the go comes from Airvisual, whose parent company IQAir has significant experience in this sector and also offer well reviewed HEPA-filters (see below). IQAir also manufacture home devices that measure in-door air pollution status in your home. Whether these devices add significantly useful information to freely available outdoor pollution information is a different question. However, should you wish to buy one of these home monitoring devices, they cost about US $300. The mobile app is available for free and provides a well designed overview of current local pollution levels and pollution forecast.

Download on the App Store | Download on Google Play


Protecting yourself

Inside the home

The introduction on the website of the Australian Department of Environment and Energy may help you get started on the topic of particle born air pollution. Airborne particles are often classified by their size, or aerodynamic diameter. We’re talking very small particles here: this size is typically measured in the micrometer range. A micrometer is a thousand of a millimeter. In air pollution, there’s a lot of talk about particles smaller than 10 micrometers, referred to as PM10, and those smaller than 2.5 micrometers, called PM2.5. To put this into perspective: a human hair seems like a giant compared to these with a diameter of 50-100 micrometers.

Small air borne particles such as PM10 and PM2.5 are troublesome for a number of reasons. While particles bigger than 10 micrometers are generally caught by our body in the nose or throat and simply sneezed or coughed up, particularly PM2.5 sneak through this barrier and tend to travel deeper into the peripheral airways of the lungs. Our lungs might not be able to bring up these deep seated particles, meaning they can potentially stay there for a very long time. The long-term effect of these particles on our lung health has not been fully researched yet but prolonged exposure to high levels of PM2.5 is known to lead to decreased lung and overall health, increased rates of lung cancer and can lead to earlier death. These particles are difficult to filter from the air using masks or air purification devices unless you are using specialised equipment. The US Environmental Protection Agency has a quick overview that helps get a better grip on the sizes we’re talking about with PM10 and PM2.5.

By now you may well be wondering how to reduce the level of air pollution in your home. Many people contemplate using their air condiitioner with its built-in filter to take care of potentially hazardous air particles. While this may sound like a good idea, this approach unfortunately won’t help much. The filters in air conditioners are designed to hold back comparably large particles and are not at all up to the task of holding back those very small air born particles. Air conditioners will not help reduce your in door air pollution from hazardous smoke.

Helping reduce in-door particulate pollution – HEPA filters

As a general rule, avoid airing your home during high levels of air pollution. If it is hot inside try using fans to keep the air moving. Some air conditioners offer a ‘recirculation’ mode that re-circulates indoor air rather than air from the outdoor environment. If in doubt, discuss with your air-conditioning specialist or manufacturer.

HEPA (high-efficiency particulate air) filters are devices that can clean the air in enclosed rooms from particulate matter. Certified HEPA-filters can filter at least 99.97% of air particles as small as 0.3 micrometers, some can filter a sizeable amount of even smaller particles. This means they can effectively redduce the amount of PM10 and PM2.5 in enclosed spaces. They also filter dust, pollen, many airborne viruses and bacteria. HEPA filters were initially designed for industries that require extremely clean air, such as microchip plants, food manufacturing sites or operating theatres. Over recent years and in light of increasing pollution, smaller HEPA-filters were developed with the home or office user in mind.

HEPA filters are rated to the amount of air they can clean in a certain amount of time, measured in m³/hr. If you have a large living room you will need a more sizeable unit than you would require for a smallish bedroom. How to chose the right product goes well beyond the scope of this article. Make sure you do your research and buy a reputable brand. Keep in mind that most units require regular replacement of filter units, which can produce significant running costs. However, HEPA filters require far less energy to run than air conditioners as they do not require energy-intense cooling circuits.

Protecting yourself when going outside

Advice from the Australian Department of Health

The Acting Chief Medical Officer and State and Territory Chief Health Officers have released a statement for the general public and health professionals about the use of masks by people exposed to bushfire smoke.

In this document you will find official advice on the use of masks while outdoors during periods of significant air pollution. The official position is to limit the use of face masks to:

  • those belonging to a high risk group
  • those who have to work outside and
  • people returning to their properties in burned areas

Particularly vulnerable groups

If you or the person you are looking after belong to any of the following groups you will need to exercise particular caution during periods of poor air quality. If you think you will need to be outdoors discuss options with your doctor.

  • Pregnant women.
  • Chronic health conditions, including
    • Cardiovascular disease, angina
    • Asthma and other chronic lung illnesses
    • Diabetes
  • Senior citizens
  • Young children and those with a history of chronic neonatal lung disease

Staying informed

People in many regions like India, China and Southeast Asia have long used face masks to protect themselves from environmental air pollution.

Masks designed to filter PM2.5 were previously mostly used in industries involving air contaminated by dust and smoke. Like many of the previously discussed products, the rise of world wide air pollution has led to a significant increase in types of masks available. Masks claiming to filter 95% (N95 respirators) or even 99% of PM2.5 (N99 respirators) are now available in many shapes and sizes for people of all ages and come as one-time use or re-usable and washable models.

Prices vary significantly from about $1 for a one-time use mask to hundreds of dollars for professional looking devices with replaceable filters. A significant problem for consumers lies in the difficulty in knowing whether a certain mask actually filters as well as the manufacturer, often very boldy, claims. Most work in the field has been done on medical N95 face-masks – and even these rarely filter more than 80% of particles. If at all possible, aim to buy masks with independent research showing their efficacy. Keep in mind that even the best mask will not help much if it doesn’t seal well to your face as unfiltered air will enter your mouth and nose through these openings. This is a particular problem in smaller children.

It’s useful to know that even masks designated as ‘one-time use’ can be used for longer, often around a week or so, unless you plan to use them in a healthcare environment. Please note that the official advice from the Australian Department of Health is to change masks multiple times a day. However, people in countries with many years of experience with significant pollution levels have found (and measured) masks to remain efficacious for longer periods. Aim to keep your masks dry as their filtering ability deteriorates steeply when they get wet. Use your best judgement and, if in doubt, replace your mask.