Qualité de l’air à Dallas

Does Dallas have bad air quality?

Dallas is among the most polluted cities in the United States for both PM2.5 and ozone air pollution. In 2019, Dallas failed to meet nationally mandated attainment levels for 24-hour PM2.5 pollution, ozone days, and annual PM2.5 pollution. As a result, nearly 1.5 million residents deemed ‘sensitive individuals’, including children, the elderly, and those with heart and lung disease were at heightened risk for experiencing adverse health effects.

In 2019, Dallas’s annual air quality index level was rated ‘moderate’, posing some risk to sensitive groups. A report by the Environment Texas Research and Policy Center found that the Dallas-Fort Worth area experienced 106 days of poor air quality that exceeded “good” AQI standards¹. More up to date information on recent air quality readings will be available further below in the article.

PM2.5 is the term for airborne particles measuring 2.5 micrometers or less. These particles include airborne dust, dirt, soot, smoke, chemicals, and metals, among others. Due to its very small size, PM2.5 can remain suspended in the air for long periods of time and penetrate the lungs into the bloodstream when inhaled, causing far-reaching health effects. Exposure to PM2.5 has been associated with cardiovascular and respiratory disease, cancer, and early death².

According to the World Air Quality Report, the city of Dallas ranked fourth in the state of Texas for PM2.5 pollution in 2019. Irving of Dallas county was the second most polluted city in Texas, trailing Longview by just 0.2 μg/m³.

The World Health Organization (WHO) recommends that annual PM2.5 exposure not exceed 10 μg/m³ in 2019, both Dallas and Irving failed to meet this standard, reaching annual PM2.5 averages of 12.3 μg/m3 and 13.7 μg/m³, respectively. In comparison, the city of Los Angeles, frequently regarded as one of the most polluted US cities, averaged 12.7 μg/m³, reporting cleaner air in 2019 than Irving and just slightly more polluted air than Dallas.

Observe real-time variations in particle pollution across Dallas county by exploring the Dallas air pollution map. While many cities tend to experience elevated pollution in population-dense areas, Dallas frequently experiences higher pollution levels near the city outskirts, where the industry is primarily located.

Ozone (O₃) is another dangerous and prevalent air pollutant in Dallas. The 2019 State of the Air report rated Dallas an “F” for ozone pollution for its number of annual days (weighted across two years) that exceeded ozone standards³. From 2016 to 2018, 8.2 days were deemed unhealthy for ozone pollution, more than doubling the 3.2-day national standard. In the two decades since ozone standards were established, Dallas has never reached its attainment.

Following live air quality data in Dallas and taking action when pollution levels exceed standards is the best way to reduce your exposure to harmful air pollution. Use Dallas’s forecast air quality data to plan ahead and avoid outdoor activities when pollution levels are expected to be high.

Why is there air pollution in Dallas?

Overall, Dallas air pollution levels have improved over the last two decades. This improvement trend has not been a straight line, however. 2019 was particularly off-trend, experiencing both heightened levels of PM2.5 and ozone pollution.

Ozone levels have wavered year after year, though a trend line shows significant improvement in the long term. Since 2015, however, ozone levels have actually been on the rise. The number of ‘unhealthy’ ozone days have increased from a weighted average of 5.3 days from 2014 to 2016, to 6.7 days from 2015 to 2017, to 8.2 days from 2016 to 2018.

Pollution from increased vehicular emissions as a result of more cars on the road, poorly regulated industry as a result of loopholes and low penalties for breaching emission regulations and other sources combined with the area’s relatively high temperatures and stagnant air make Dallas Fort Worth an ideal incubator for ozone⁴. The US EPA, moreover, has made meeting targets more challenging by gradually lowering ozone standards. In recent years, ozone requirements have fallen from 75 ppb to 70 ppb in order to better serve at-risk communities. Many health experts are advocating for even lower thresholds in order to save more lives⁵.

In 2020, lockdown measures as a result of the COVID-19 pandemic are expected to have resulted in fewer cars on the road and slightly reduced industrial activity. Data is now available pertaining to this time period, which will be discussed in short.

What are some further causes of pollution in Dallas?

Dallas’s unhealthy AQI is primarily the result of transportation and industry emissions. Since 1997, emissions from transportation have increased by 27% per capita in the Dallas–Fort Worth area⁶. Of the 10 most populous cities in the United States, only Chicago had a larger increase. This trend is largely attributable to a growing population, more cars on the road, and longer commutes. An estimated 76% of cars have just one person inside. The average commute (26.6 minutes) is a minute longer than the national average.

In order to reduce transportation emissions estimated to contribute to 74.8% of total emissions, residents should transition to more energy-efficient, low-emission vehicles. While Dallas has promoted carpooling, built more bike lanes, and upgraded the city fleet of vehicles, there is still an opportunity to further promote change through the use of electric car rebates and an increased supply of electric vehicle (EV) charging stations.

Industrial and petroleum activity is another major contributor to Dallas air pollution. A report published by the Environment Texas Research and Policy Center found that industrial facilities in North Texas were responsible for emitting 78,737 pounds of illegal, non-authorized air pollution in 2017⁸. This represented a 27% increase from the year before.

Five of Dallas’s top industry polluters include Owens Corning Insulating Systems plant in Waxahachie, a Garland Municipal Power plant, a Tamko Building Product facility in Dallas, a Conecsus facility in Kaufman County, and a Bridgeport Gas plant in Wise⁹.

While current laws carry severe penalties for over-polluters, these laws are rarely executed to their full potential. In 2018, Texas facilities only paid $2 million in penalties for illegal emissions - a small fraction of the $297 million that could have been levied¹⁰. Closing existing loopholes and requiring industries to remain within the confines of the law present a significant opportunity in reducing Dallas air pollution.

In June 2020, Dallas experienced a significant albeit unusual pollution event when winds carried a thick cloud of dust from the Saharan Desert over the Atlantic and to the Dallas-Fort Worth area. The sandstorm produced the thickest dust that the area has seen in at least 20 years, with air quality levels reaching the “unhealthy” rating¹¹. As deforestation becomes a growing problem as a result of our warming global climate, such international influences could become more prominent.

What was the level of air pollution in Dallas in 2020?

Observing some of the data taken in more recent and up to date times (with 2020 being of great prominence due to the worldwide effects of the Covid-19 pandemic being felt), it can be seen that Dallas made some fairly significant improvements when compared to 2019, which is what many people were pre-empting to happen due to the cessation of the mass movement of people and vehicles.

Despite this, it did not hold true for all cities across America, as well as throughout the world as expected, with pollution levels rising even higher in certain places for a number of reasons. Regarding Dallas, in 2020 it came in with a yearly average PM2.5 reading of 9.6 μg/m³, a reading that placed it just within the World Health Organizations (WHO's) target goal of 10 μg/m³ or less for the most optimal quality of air. Whilst this is on the higher end of the ratings bracket, it still shows a marked improvement from the previous year, going down two whole ratings, moving from its previous years PM2.5 reading of 12.3 μg/m³ which classed it as ‘moderate” (12.1 to 35.4 μg/m³ required for classification) down to the WHO's target goal.

This reading of 9.6 μg/m³ placed it in 2780th place out of all cities ranked worldwide, indicating a fairly respectable placing amongst the world circuit, one that is considerably improved from its 2019 placing. Whether this will stay in place as full activity is resumed over the coming years is yet to be known, but as of now the citizens of Dallas have had a year of much cleaner air quality, free from larger accumulations of smoke, haze and polluting clouds. Of note is there were a few months that went up mildly in their PM2.5 readings, for reasons that have been touched upon in the previous questions (typically anthropogenic activity coupled with certain meteorological occurrences).

When does Dallas have the best air quality?

Looking at the months' data collected over the course of 2020, it can be seen that there were periods of time in which the PM2.5 levels were significantly lower than in other months of the year. As mentioned briefly at the beginning of the article, PM2.5 refers to particulate matter that is 2.5 micrometers or less in diameter, comprised of many different materials and on occasion going down to sizes of 0.01 microns or beyond in diameter. This extremely small size makes it a major health hazard when respired (as well as the various materials it is made of sometimes having highly damaging or carcinogenic properties to human health), and as such it is used as one of the main components in the calculation of the overall AQI, or air quality index.

Over the course of 2020, Dallas had six months of the year come in with a WHO target rating of 10 μg/m³ or less, with the remaining six months coming in with a ‘good’ air quality rating, one that requires a very fine margin of entry at 10 to 12 μg/m³ for classification. Starting with the months of higher pollution before moving onto the cleaner ones, the months of January, March, April and August through to October all came in with ‘good’ ratings of air quality, with PM2.5 readings of 10.5 μg/m³, 11.1 μg/m³, 10.3 μg/m³, 10.1 μg/m³, 10.4 μg/m³ and 10.1 μg/m³ respectively.

This indicated that March was the most polluted month of the year with its reading of 11.1 μg/m³, being 1 unit away from moving up into the next pollution bracket (the moderate ranking one). August through to September remained as the longest stretch of higher PM2.5 readings, meaning that this was a period of time in which the air may be slightly unhealthier to breathe, with a higher amount of chemical compounds and hazardous particulate matter suspended in the atmosphere.

Moving onto the cleaner months, the ones that came in within the WHO's target goal were February, May through to July, as well as November and December. These came in with PM2.5 readings of 8.3 μg/m³, 7.3 μg/m³, 9 μg/m³, 8.4 μg/m³, 9.7 μg/m³ and 9.8 μg/m³ respectively over the aforementioned months. This indicates that May was the cleanest month of the year with its reading of 7.3 μg/m³, as well as that particular period (May through to July) being the time in which there were three uninterrupted months of the WHO’s level of air quality.

What are some health issues associated with breathing polluted air in Dallas?

Whilst the level of air pollution was shown to have dropped moving from 2019 to 2020, it must be mentioned that any reading of air pollution has the ability to cause harm or adverse effects, and this possibility goes up significantly as the PM2.5 count goes over the WHO's target goal, as well as other factors playing a part, such as the health status of individuals who are exposed, as well as the length of pollution exposure as well as the severity of it.

As an example, those who live near busy roads or industrial areas, as well as individuals who have a job that requires them to be near or in high pollution areas or facilities (such as miners or certain factory workers) being even more at risk.

Some of these health issues include ones such as ischemic heart disease, whereby the tissue of the heart fails to receive enough oxygen and thus the tissue gets damaged. This can lead to a whole host of further cardiac complications, including a heightened risk of heart attacks and arrhythmias, as well as other terminal conditions such as strokes. Respiratory ailments are amongst the most common, with ones such as pneumonia, emphysema, bronchitis and aggravated forms of asthma all presenting themselves amongst affected individuals.

+ Article Resources
[1] Ridlington E. (2020). Trouble in the air: millions of Americans breathed polluted air in 2018.
[2] Xing Y, et al. (2016). The impact of PM2.5 on the human respiratory system. doi: 10.3978/j.issn.2072-1439.2016.01.19
[3] American Lung Association. (2019). State of the air – 2019.
[4] Green Dallas. (2020). Air pollution.
[5] Song L. (2013, October 23). What's behind surging ozone pollution in Texas? Study to weigh role of fracking in health hazard.
[6] Lawrence M. (2019, October 17). DFW auto-emissions grow disproportionately to the population.
[7] Green Dallas. (2020). What is the city doing?
[8] Pabst E. (2020). Illegal air pollution in Texas: Air pollution from startups, shutdowns, malfunctions and maintenance at industrial facilities in Texas in 2018.
[9] Jimenez J. (2019, December 18). Report lists top 10 polluters in North Texas.
[10] Nowlin S. (2019, December 18). Illegal air pollution has increased exponentially in the San Antonio area, according to new report.
[11] Ray J. (2020, June 27). Saharan dust cloud causes North Texas air to be deemed ‘unhealthy’.