Bushfire smoke can pose a health risk to recreational and high performance athletes. The health impact of bushfire smoke can vary based on an individual’s current health status and previous medical conditions. Current public health advice is aimed at high-risk groups, including people over 65, children 14 years and younger, pregnant women and those with existing heart or lung conditions. However, athletes involved in high performance sport can also be at increased risk while performing high intensity prolonged exercise outdoors and additional caution should be taken.

When pollution exposure is at low levels, the respiratory tract’s usual defence mechanisms trap, transport and clear pollutants effectively. With elevated exposure, short-term accumulation can occur resulting in inflammation and this can exacerbate a number of health conditions with asthma being the most common in athletes.

During exercise, respiratory rate and volume increases, this in turn increases the total airway exposure to pollutants. In high performance athletes, moderate exercise can increase the total amount of air passing through the airway by more than 10 times and vigorous exercise by more the 20 times, compared to resting values. Even at moderately reduced air quality, this can represent a significant increase in pollutant exposure during a one-hour, high intensity training session.

Most State and Territory government websites (except for Tasmania and Victoria) present air quality information as the ‘Air Quality Index’ or AQI calculated from a 24-hour average. The AQI is calculated for a number of pollutants (including fine and coarse particulate matter, carbon monoxide and ozone). It was designed as a way to standardise information across these different types of air pollution. This means that the AQI number is not a raw measurement (e.g. micrograms of pollutant per metre cubed of air), but a scale based on how much the reading is above (or below) the air quality standard. Some States and Territories provide the AQI separately for different pollutants, others provide only a composite AQI that is based on the pollutant that is the worst. For more details on how the AQI is calculated in your area, please see your local air quality agency’s website.

PM2.5 are very small particles usually found in smoke. They have a diameter of 2.5 micrometres (0.0025 mm) or smaller. PM2.5 particles are a common air pollutant. Breathing in PM2.5 particles can have negative effects on your health. PM2.5 particles are small enough for you to breathe in deeply into your lungs. Sometimes particles can enter your bloodstream.

PM2.5 is measured at all air quality measuring sites in Australia. The other pollutants that make up the AQI are not measured everywhere in Australia. This means that PM2.5 has the relevance for providing a standardised guidelines for all of Australia. PM2.5 is also by far the most important air pollutant in smoky conditions.

Smoke concentrations in the atmosphere can vary markedly within a short distance (e.g. 2 km) and can change rapidly over time. 24 hour rolling average of PM2.5 is useful for knowing the average PM2.5 levels in the air over the past 24 hours, at a point in time. The 24 hour rolling average does not, however, necessarily give an accurate understanding of real-time PM2.5 concentration.  For individuals wishing to make decisions about whether it is safe to exercise now, or over the next couple of hours, having real-time or hourly averages of PM2.5 is important.

For these reasons, the AIS guidelines are based on real time or hourly PM2.5 readings.

There are three ways to get information on PM2.5 concentration levels (measured in µg/m³):

1. State and Territory air quality monitoring websites (hourly measures of PM2.5 concentration)
2. The AirRater App (or other similar App providing real time PM2.5 in µg/m³)
3. A handheld portable device that measures PM2.5 in real time

State and Territory air quality monitoring websites:

The following links will be useful in helping you find the relevant website in your State:

• Australian Capital Territory
• Victoria
• New South Wales
• Queensland
• Western Australia
• South Australia
• Tasmania

Unfortunately, different States and Territories have slightly different systems for measuring air pollution, different means of presenting information and varying categories and systems for different levels of pollution (good, fair, moderate etc.).

The AirRater App was originally funded by the Australian Government and is currently funded by the Menzies Institute for Medical Research. AirRater draws its air pollution information from State and Territory air quality monitoring networks. It presents information on PM2.5 concentration in mcg/m³ and applies the same system of measurement for all locations in Australia. To find out more about how AirRater sources and presents its data visit: https://airrater.org/air-quality-explainer/.

There are range of commercial handheld measurement devices available for measuring PM2.5 concentration in the atmosphere. It is important that the device used is designed for measurement of outdoor rather than indoor concentrations of PM2.5. Teams and sporting clubs may wish to utilise one of these devices for providing real-time measures of PM2.5 concentration at their specific location at the time that they wish to exercise. That value can then be used to advise athletes and officials about appropriate exercise activity.

Table 1 below has drawn on information from several of the Australian State and Territory websites and modified information specifically for application to decisions around physical exercise in smoke affected environments. There are many factors that contribute to readings found on State and Territory websites, air quality apps and handheld devices. The numbers on the table below are a guide and should not be taken as absolutes. There is a need to use common sense in assessing the environment and utilising other factors such as visibility in making a decision about whether or not exercise is appropriate.

Table 1. Guidelines for exercise in smoke affected environments

The above table provides exercise guidelines but individuals should also remember that there is high variability in PM2.5 across relatively short distances and quite rapid changes across time. Those wishing to exercise should also take note of the visibility and keep in mind their own individual experience of sensitivity to smoke pollution. The following visibility guidelines should be considered in conjunction with the information from the above table. These visibility guidelines are based on those of the Victorian Environment Protection Authority

Table 2. Activity levels based on visibility

• Air quality information on State and Territory government websites is generally updated hourly; therefore, there can be a lag between official measurements and what is occurring in real time. This can cause limitations when it comes to determining the air quality in your local environment. If smoke is affecting usual visibility within your area, it is likely that the air quality will fall into a higher risk category.
• Consecutive days of exposure to polluted air can have a cumulative effect, lowering an athlete’s threshold for symptoms. This should be considered if your region has been exposed to increased smoke for several days in succession.
• Increases in exercise intensity and duration result in increased airway exposure to polluted air. The AIS recommends modifying training or training locations based on the table above.
• All athletes who suffer from asthma should have an updated asthma management plan and consult their doctor prior to exercising in smoke-affected environments.
• Recent respiratory infection increases the risk for development of smoke-related symptoms, even in non-asthmatics.