What's in the air today?: Communicating air pollution information to the public

Jim Mills questions the use of Air Quality Indexes (AQI) versus actual pollutant concentrations when communicating information about air pollution to the public.

Air pollution poses a significant threat to public health and the environment.

Effective communication strategies are crucial for raising public awareness and encouraging protective actions.

The Air Quality Index (AQI)

AQI’s are colour-coded and numerical scales that provide a simplified overview of air quality.

They convert pollutant concentration data into a single, easily understandable index number and associated colours corresponding to a category description (eg Good, Moderate, Unhealthy for Sensitive Groups, Unhealthy, Very Unhealthy, Hazardous etc).

There are also a wide variety of these AQIs used around the world. All with different index levels, based on WHO, EU, UK, USEPA or other guidelines or regulations.

So although intended to simplify the information, the array of differing AQIs can actually confuse the recipient.

Advantages of the AQI

Simplicity and accessibility

The AQI offers a straightforward way for the general public to understand air quality.

Its colour-coded system makes it easier to grasp the severity of pollution at a glance.

Action-oriented messaging

Each AQI category is often accompanied by recommended actions for different population groups (eg "reduce prolonged or heavy exertion").

This makes it easier for individuals to take appropriate precautions.

Comparability

The AQI allows for easy comparison of air quality across a region over time.

Disadvantages of the AQI

Lack of specificity

While simplifying information, the AQI can obscure the specific pollutants contributing to poor air quality.

This lack of detail might prevent individuals from understanding the particular health risks associated with different pollutants.

Variations in calculation

The calculation of the AQI varies between different agencies and countries. This could potentially lead to confusion.

Limited health guidance

While providing general guidance, the AQI may not offer sufficient specific health information for individuals with pre-existing conditions who require more detailed data.

Actual pollutant concentrations

Presenting actual pollutant concentrations involves providing measurements of specific airborne contaminants. Such as particulate matter (PM2.5, PM10), ozone (O3), nitrogen dioxide (NO2), sulphur dioxide (SO2) and carbon monoxide (CO), usually in units like micrograms per cubic meter (µg/m³) or parts per billion (ppb).

Advantages of actual pollutant concentrations

Precision and detail

Providing actual concentrations offers precise data on the levels of individual pollutants.

This allows for a more nuanced understanding of air quality and associated health risks.

Targeted health advice

Specific pollutant data is more useful for medical professionals and researchers in providing targeted health advice and conducting epidemiological studies.

Scientific accuracy

For those with a scientific background or a deeper interest in air quality, actual concentrations offer transparent and accurate information.

Disadvantages of actual pollutant concentrations

Complexity for the general public

Raw pollutant data is overwhelming and difficult for the average person to interpret without specialised knowledge.

Lack of immediate actionability

Without a clear interpretative framework, it is challenging for the public to understand what actions to take based on specific concentration values.

Potential for misinterpretation

Without proper context and explanation, pollutant concentrations could be misinterpreted, leading to unnecessary alarm or complacency.

Recommendations for more effective communication

To best communicate information about air pollution to the public, it's best to use a hybrid approach that leverages the strengths of both the AQI and actual pollutant concentrations.

Messaging should clearly state the AQI level by colour, its meaning and recommended actions.

Alongside the colour displayed at each monitoring location on a map, it's possible to display the actual concentration of the specific pollutant (as well as, or in place of the index band). This would allow the public to see the variation across an area. A well as compare that concentration against the relevant standards or target values.

When each location on the map is selected, we can present information with clear explanations of what each pollutant is, its health effects and safe exposure limits.

Visual aids such as charts and graphs can also help make this data more impactful.

Regardless of the primary communication method, it is crucial to provide context and educational resources. This includes:

• Health impacts: clearly explaining the health effects of air pollution, both short-term and long-term, for different population groups
• Sources of pollution: informing the public about the main sources of air pollution in their area
• Protective measures: offering practical advice on how to reduce exposure and protect health
• Forecasts: provide air quality forecasts to enable proactive planning.

Local authorities should develop channels and materials for sensitive populations (eg children, the elderly, individuals with respiratory or cardiovascular diseases).

This might involve direct communication with healthcare providers, community organisations and schools

Conclusion

Effective communication of air pollution information requires a balanced approach.

While AQIs serve as a simplified tool for mass communication and help to guide immediate actions; providing access to actual pollutant concentrations allows for deeper understanding and caters to specific needs.

By combining these approaches along with educational resources, we can empower individuals to make informed decisions. And, if necessary, take necessary precautions to mitigate the risks associated with air pollution.

This hybrid approach has recently been introduced by the Breathe London air quality network.