The South DeKalb
Data Story

What's In the Air?
Air Quality in S. DeKalb

Research Question 3:
How have levels of key air pollutants, such as PM2.5 and Ozone, changed over the past years in DeKalb County (2016-2023)?

PM2.5

Particulate matter 2.5 (PM2.5) refers to tiny particles or droplets in the air that are two and a half microns or less in width. These particles are extremely relevant in discussions of air pollution due to their ability to penetrate deep into the lungs and even enter the bloodstream, posing significant health risks. Chronic exposure to PM2.5 can lead to severe health issues such as respiratory and heart diseases, reduced lung function, and even premature death. The small size of these particles allows them to bypass the body's natural defenses, making them especially dangerous. Consequently, monitoring and controlling PM2.5 levels are critical for public health, and they serve as key indicators in the assessment of air quality in urban and industrial areas.

This graph tracks the number of days that particulate matter levels, specifically PM2.5, exceeded the standard in DeKalb County, Georgia, over a range of years.

From the start of the period, there's a steep decline from 2016 to 2017 in the number of days exceeding the PM2.5 standard, indicating an improvement in air quality. The following years see a gradual increase until 2020, suggesting a worsening trend where more days are registering unhealthy levels of PM2.5.

However, after 2020, there's a dramatic drop to 2022, showing a significant reduction in the number of days with elevated PM2.5 levels. The levels in 2022 are notably lower than at any other point on the graph, which could suggest a substantial improvement in air quality concerning fine particulate matter in DeKalb County. This improvement could be due to successful air quality management policies, changes in local emissions, or other environmental factors.

In this graph, the trend of PM2.5 levels over several years is presented for DeKalb and Henry Counties in Georgia, with a focus on the ratio of days the PM2.5 levels exceeded air quality standards out of days measurements were taken.

From this graph, it is evident that DeKalb County has a greater ratio of days where PM2.5 exceeds the standard than Henry County for all years except 2019. This may be explained by the fact that DeKalb County is more urbanized, with denser populations and higher traffic volumes, contributing to greater PM2.5 emissions from vehicles.

Ground-level Ozone (Smog)

Ozone is a type of oxygen molecule made up of three oxygen atoms. It can be both good and bad. High up in the atmosphere, ozone forms a layer that protects us from the sun's harmful ultraviolet rays. However, at ground level, where we breathe, ozone is a harmful pollutant, often referred to as smog. It's created when sunlight reacts with pollutants from cars and factories. Breathing in ozone can irritate our lungs, make it hard to breathe, and worsen conditions like asthma. So, while it's helpful high above us, ozone at ground level is a major air pollutant that can harm our health.

This graph shows the number of days that ozone levels exceeded the standard limits in DeKalb County, Georgia over a span of several years. Starting from 2016, we see an upward trend in the number of days with ozone levels above the standard, reaching a peak around 2019. This suggests that air quality in terms of ozone pollution was worsening, with more frequent occurrences of high ozone levels.

However, after 2019, there is a sharp decline in the number of days exceeding ozone standards, reaching a low point in 2023 that is below the starting point in 2016. This indicates a significant improvement in air quality with respect to ozone levels in the recent years shown on the graph.

The graph is useful for understanding trends in air quality over time and evaluating the effectiveness of measures taken to reduce ozone pollution. The sharp decline after 2019 might suggest that such measures have been successful, or that there have been changes in factors affecting ozone levels, such as reduced emissions from traffic and industry, which occurred during the height of COVID-19, or other environmental policies that have been enacted.

The plot tracks the ratio of days that ozone levels exceeded the standard in DeKalb and Henry Counties, GA, from 2016 to 2022. Throughout this period of time, DeKalb County maintains a lower ratio of days where ozone exceeded the standard compared to Henry County. This demonstrates that. Interestingly, DeKalb and Henry County demonstrate different trends indicating the differing environmental conditions or management policies in the two counties.

Conclusion

Our analysis showed graphs where pollutants like metals in drinking water and PM2.5 decreased in recent years. On the surface, there's no longer reason to worry about air and water pollution, but this conclusion would be wrong. Why?

Legal may not mean safe. Not all testing is done with the same metrics or methodology. Prominent nonprofit organizations like the ALA and Environmental Working Group (EWG) have called for stronger limits on air and water pollutants, respectively. The ALA warns that even short-term spikes in particle pollution can be deadly. The EWG argues there are frequent discrepancies between the legal limits for contaminants and guidelines and recent scientific studies. With data from 50,000 local water utilities across all 50 states, the EWG found that in South DeKalb, cancer-linked THMs were 225 times their guideline.

Regardless of stance on these discrepancies or disagreements over thresholds, the aim is to bring environmental pollution as low as possible.

Limited and incomplete data. Using the available datasets we found from local and governmental entities, we could only trace the trends back so far. Gaps in the records and a historical lack of testing limited the scope of our analysis. With new legislation and advocacy and action from community members and organizations, testing has only started to become more robust, and we must remember that...

Context is needed. We want to have as much context as possible when looking at how things change over time. We can't be too hasty and conclude that levels have naturally gone down or that a decrease will stay. There are usually other factors at play. Bringing in the information that the graphs don't show helps us better understand the changes that have occurred and how to maintain the positive ones.

During the 1996 Summer Olympics, Atlanta made major efforts to reduce traffic congestion including downtown road closures and increased public transportation. The CDC linked the consequent drastic reduction in vehicle emissions to a decrease in emergency room visits for asthma. Similar dramatic improvements in air quality occurred in 2020. With the COVID-19 pandemic leading to lockdowns and transitions to remote work, smog decreased dramatically with reduced vehicle emissions.

It is promising that recent improvements in air quality have continued, possibly due to new vehicles and teleworking. These reasons suggest that positive trends won't continue unless we maintain efforts to mitigate pollution and enforce regular testing.

Improvements inspire hope, but there is still a long way to go. We are happy to see decreases in air and water contaminants, but conditions are still unfavorable. While our analysis showed a reduction in days of the year that PM2.5 exceeded the standard, that number decreased to around 140, meaning for more than a third of the year, the amount of particulate matter in the air is still too high. The same follows for ground-level ozone or smog. While the ALA reported that Atlanta experienced a record low number of unhealthy, high ozone days, the city still received an "F" grade for ozone pollution.

Overall, our analysis suggests that the name of the game is to "keep on."