Understanding Your Local Air Quality

These days, air quality information is so prevalent that it can be viewed alongside the daily weather on a phone or television. Satellite data can be accessed through the internet to evaluate air quality on a broader scale regardless of where one is on the globe. One thing that stands in the way, other than access to these resources, is the ability to understand what it all means, and how to use it. Here I’ll cover how to use this data to your benefit, without going full Dr. Brown from Back to the Future.

Aerosol Optical Depth over Madagascar Oct 31-Nov 10 from NASA Worldview.

Here is a snapshot of aerosol optical depth that I captured using publicly available satellite data on NASA Worldview. There are many different layers to be viewed with this tool other than aerosol optical depth, such as flooding, sea ice coverage, fire, and more. This information is useful to those who are planning hurricane rescue missions, delivering shipments, fighting fire, considering their exposure to pollution, and more. Aerosol optical depth, or AOD, is a way of understanding the amount of polluting particles in the air. If these air particles are rare and there is a clear sky, AOD is 0.1. When that number reaches 3.0 or higher, the particles are densely packed together and the sun would no longer be visible through the smog. NASA Worldview’s website offers tutorials for those who wish to explore other layers, create moving images, or download data.

If interested in air quality in the United States, there are a number of free tools provided by the Environmental Protection Agency, such as Air Data Plots or AirNow. Below is the current air quality in a suburb of Atlanta, Georgia according to AirNow. The website describes that the air quality in this city is “moderate” and warns people unusually sensitive to particle pollution to limit outside activity. However, sometimes indoor air is more of a health risk than outdoor air. I wrote about some of the things that can reduce indoor air quality in a previous blog post. Repairing leaks, maintaining existing air systems, and installing mechanical ventilation systems in new homes can help keep indoor air clean.

Year-round air quality in different areas of the United States can also be viewed by selecting a city, the pollutants of interest, and the year using EPA’s AQI Plot tool. Particulate matter smaller than 2.5 µm in diameter (PM2.5), or fine particulate matter, is an important pollutant that can be looked at with this tool. PM2.5 can be a secondhand or original product of any suspended liquid or solid. The reason why these ambiguous particles are so dangerous are that they have lethal symptoms. Some risks of short to long term exposure to PM2.5 are premature death (years of life), heart attack or stroke, increased severity of asthma attacks, diabetes, lung cancer, impaired cognitive functioning, higher risk of Parkinson’s disease, Alzheimer’s disease, or dementia, and more.

Another important pollutant is ozone. Ozone can damage plants and reduce crop yields, so is a factor that farmers might consider. Ozone can worsen symptoms for those with COPD or asthma and lead to the development of those diseases in others. It can also lead to brain inflammation or structural changes in the central nervous system, cognitive decline, metabolic disorders (e.g., hyperglycemia), reproductive and developmental harm, reduced fertility (e.g., preterm birth, stillbirth), and more.

The image above displays that PM2.5 concentrations might be a bigger problem in Atlanta, Georgia than ozone. It all depends on the perspective, though. Ozone levels in 2021 frequently surpassed a moderate level, but never ventured as far as unhealthy for all groups. Although there were four days in 2021 when ozone was at levels unhealthy for sensitive groups, PM2.5 reached a level that was unhealthy for everyone during the peak of summer. PM2.5 and ozone are both predominantly found in concentrations that are good or moderate in this region, although pollution can reach higher levels in the summertime. However, hot weather is not the only cause of this issue, as there were levels of PM2.5 that were unhealthy for sensitive groups as late as October of this year. That being said, air quality in the United States has made huge improvements over time due to the Clean Air Act, which I wrote about in a previous blog post.

One last free, public air quality monitoring tool is the Hybrid Single-Particle Lagrangian Integrated Trajectory model (HYSPLIT) developed by the National Oceanic and Atmospheric Administration’s Air Resources Laboratory. Run forward or backward trajectories using this tool to determine where air pollution in a specific location will go to next, or came from. I used this site to determine where the air currently hovering 500 meters above Atlanta will be in the next 18 hours. The answer? Somewhere over North Carolina. I hope they like the smell of cornbread and baby back ribs. Just kidding! Atlanta doesn’t really smell like anything in particular, unless you really do have your nose to a pile of ribs.

HYSPLIT model results over Atlanta, Georgia beginning around 4 pm on Nov 16, 2021.

Now that you have this information, will you be checking your local air quality through your weather app or another tool before taking that next trip into town? Or do you prefer just looking out the window to get timely updates about the weather? Let me know!

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