Avoiding misrepresentation of statistics means looking at all the data

Published on November 07, 2024

Air quality and pollution are complex topics, yet they’re often boiled down into eye-catching statistics. Statements like "oil and gas development is responsible for 60% of Colorado's air pollution" may sound definitive, but they don’t tell the full story. To understand what these statistics mean for our health and environment, we need to dig a little deeper into how the data is collected, what it represents, and, just as importantly, what it doesn’t. Let’s use a recent air toxics report by the Colorado Department of Public Health and Environment (CDPHE) as an example.

Air Pollution is More Than Just Air Toxics

When we talk about air pollution, it’s important to recognize the air we breathe  can have different types of pollutants that may or may not have health-based standards from sources that may or may not be regulated. This soup of air pollutants includes  ozone, particulate matter, greenhouse gases, and air toxics. Each category has different impacts on health and the environment, and no single number captures all pollution types. For instance, there have been statements made suggesting that oil and gas contribute 60% to air pollution based on air toxics data from the CDPHE report. This is misleading because air toxics does not solely represent air pollution. Furthermore, the data in that report focuses on very specific source sectors and does not include contributions from vehicles or wildfires.

 Additionally, this only considers the amount of air toxics and not the health risk they pose to people. The report does in fact use the EPA’s Risk Screening Environmental Indicators (RSEI) to weight the relative toxicity of different chemicals, revealing that when looking at the reported air toxics emissions with relatively higher toxicity (more negative health impacts) to humans only 31.4% of the more harmful emissions are from oil and gas, while utilities contribute 41.4% (page 47 of report). This tells us that not all pollution is equally harmful—both the amount, type, and toxicity of emissions matter.

Reported Data Show Only a Part of the Picture

The broad assumption that the total numbers in any given report represent the whole system is a little naive. Data analysis is limited by the data included or reported. The CDPHE report only analyzed reported air toxics emissions from industries required to report air pollutant emissions per their permits. Other contributors, like vehicles, lawn equipment, and public transit, don’t have to report their air pollution emissions even though they add significantly to pollutants like ozone.

Additionally, it’s worth noting that Weld County’s reported air toxics data might seem high—45% of reported air toxics from required industries in Colorado come from Weld. However, this doesn’t mean Weld is the most polluted area. Instead, it reflects the high number of facilities in Weld that are required to report emissions.

Air Toxics Come from More than Just Human Activity

Air toxics come from both human and natural sources. The 2020 National Emissions Inventory, for instance, shows that only 19% of air toxics emissions in that year were from human activities and the majority  from wildfires (52%) and other natural sources (29%). Within that 19%, about a third is from mobile sources like cars, and just under 40% is from industry, which includes not only oil and gas but also utilities and manufacturing.

To put it into perspective, the emissions from oil and gas make up around 4.4% of total air toxics in Colorado, a much smaller piece of the pie than we might expect. It’s a reminder that while air toxics emissions from oil and gas are a valid health concern, they’re not the whole story and don’t represent the majority of the air toxics Coloradans are likely to encounter.

How You Can Stay Informed

For anyone interested in air toxics, there are ways to stay updated and participate in decisions. The Colorado Department of Public Health and Environment’s website offers recorded presentations, updates, and opportunities to connect with experts. There’s also an upcoming Air Quality Control Commission rulemaking hearing in January 2025 on identifying priority air toxic contaminants for Colorado, with further public discussions throughout the year.

If you’re interested in specific air quality questions, you can reach out directly to Weld County’s air quality policy analyst, Dr. Annareli Morales, or to state experts at CDPHE. Understanding air quality is complicated, but by asking questions and looking at all the data, we can work together for a clearer, more accurate picture.