How Dust Storms Confuse Air Quality Reports

Recently a massive dust storm stretched from the Sacramento Valley to the Mojave Desert, spreading large amounts of hazardous dust and sand. Here we explain the impact of dust storms on the air we breathe and why dust storms can sometimes present reporting challenges for air quality monitors.

What Happened?

The huge amount of dust shrouded interior California on Monday, October 11th, shutting down highways and casting an eerie glow across an area that stretched from the Sacramento Valley to the Mojave Desert.

News headlines reported high winds and rapidly increasing dust levels, warning of health risks and the need to minimize exposure to this dust pollution:

Blowing dust and sand are also likely lowering visibility and increasing particulate matter 10 microns or smaller, (PM10) in the air, creating hazardous breathing conditions, especially for those with breathing and lung conditions. The San Joaquin Valley Air Pollution Control District urged people with heart or lung disease to follow doctors’ advice for dealing with episodes of particulate exposure.” – – Fresnobee

LANCASTER, Calif. – High winds that caused dust storms prompted closures of the 14 Freeway and state Route 138 in the Lancaster area for hours before eventually reopening Monday.” – Foxla

Dust Pollution is Large Particulate Matter

When we talk about ‘Particulate Matter’ (or ‘PM’), we are referring to a group of particles suspended in the air, characterized by their size. All particulate matter is small enough to get into our lungs, causing local and systemic inflammation in the respiratory system with the potential to cause respiratory diseases such as asthma and bronchitis. It goes without saying that managing exposure to harmful particulate matter is a top priority, especially for those with pre-existing conditions.

Particulate Matter Types - in dust storms

Dust storms create relatively large particles of dust or sand that are hazardous to our health when inhaled. They are referred to as Particulate Matter and due to the relative size of the particles fall into the category of PM10 – i.e. Particulate Matter with a diameter of 10 microns or less.

The Importance of Monitoring PM10 During a Dust Storm

Sometimes, even though a provider might report good/moderate levels of air quality within the local air quality index (AQI), this information may be based entirely on particulate matter levels from PM2.5 measurements. Usually, this doesn’t cause too much of a problem because similar levels of PM10 and PM2.5 are often present at the same time.

However, dust storms are an exception to this rule. Whereas the usual ratio between PM2.5 and PM10 would usually be around 1-10 (basically the same in terms of AQI levels), during a dust storm, the ratios can reach differences of up to 70.

Example: Monitoring Station in Tracy, California

As this particular monitoring station does monitor both PM2.5 and PM10, we were able to see the difference in ratio during this week’s dust storm very clearly – note the spike in PM10. And if one were to look at only PM2.5 levels, the information would be partial and misleading, as the dust storm’s effect on the air quality is visible only when looking at the PM10 levels.

dust storms monitoring

How Dust Storms Confuse Air Quality Reports

As we’ve explained above, to truly represent air pollution for a dust storm and help the public to manage their exposure, it’s important to take into account the behavior of PM10 at a local level – not just PM2.5. However, not all monitoring stations do this.

As a result, it’s possible during a dust storm to see reports of ‘good’ air quality in terms of PM2.5 – but this doesn’t mean there aren’t high levels of PM10 around.

As awareness of the damaging effects of air pollution is at an all-time high and the general public is paying more attention to available air quality information data sources, sources of air quality information are increasing and improving worldwide.

Yet often, during extreme events like wildfires and dust storms as we’ve seen, monitoring stations don’t always report on all pollutants, often report with a time delay and can’t account for the spaces in between their monitoring stations, meaning that what is reported for a given event may not always be accurate for that specific time or pollutant.

How Does BreezoMeter Report Air Quality During a Dust Storm?

In order to report air quality during a dust storm, BreezoMeter adopts a multi-layer and multi-model approach to air quality reporting. But how do we do this?

We factor information from multiple data sources, including thousands of government monitoring stations around the globe, then we layer this information with additional data sources to account for the real-time and geographical limitations of certain governmental stations: For example, low-cost sensors which are strictly calibrated, satellite information, dispersion models, including natural phenomena models (e.g wildfire smoke models), live traffic pollution and meteorological/land cover information.

We then put it all through a process of strict validation, using advanced machine learning algorithms to account for the 1-7 hour delayed data provided by government stations to report real-time air quality.

Our unique approach to air quality reporting empowers us to provide information for PM10 in the event of a dust storm, even when there is no station data for PM10 available at a certain location.

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Dr Gabriela Adler
Dr Gabriela Adler Katz

Chief Scientist @BreezoMeter. I hold an MSc & PhD in atmospheric science and formerly worked as a research scientist at NOAA. I believe it is my greatest duty as a scientist to bring science to the people!