In recent weeks, Colorado鈥檚 air quality has rapidly deteriorated. Smog, a portion of which is composed of smoke from wildfires within and outside the state, has obscured our view of the mountains from the Front Range. And this week the state failed to meet an Environmental Protection Agency deadline for reducing ozone pollution.
Both ozone and smoke are bad for our health, but monitoring air quality can help regulators and the public make better decisions. That is, if the readings are precise enough.
An ozone breeding ground
Ozone is a secondary pollutant, so it isn鈥檛 emitted like some other gases, like carbon dioxide. It forms when exhaust materials released by cars and oil and gas production enter the air and chemically react in the presence of sunlight.
Although a layer of ozone in the upper atmosphere protects Earth, ground-level ozone is harmful. It鈥檚 also clear, so it can be difficult to evaluate air conditions by eye. And Boulder County Public Health air quality program coordinator Bill Hayes says Colorado is uniquely situated for high ozone levels.
鈥淎t higher elevation, we get greater solar irradiance than they do at sea level. So more energy to drive the reaction,鈥� he said. 鈥淎nd then because of our topography, those ozone precursors often get trapped up against the foothills, up against the mountains.鈥�
In 2008, the Environmental Protection Agency set a national ozone standard at 75 parts per billion. The deadline to reach that goal was July 20, and parts of Colorado still haven't made the cut. But that鈥檚 not the end of the story: the EPA lowered the standard even further in 2015, from 75 to 70 parts per billion.
鈥淭here is no safe level for ground-level ozone,鈥� said Hayes. 鈥淪o we actually expect that 70 parts per billion to keep being lowered to really make it a health-based standard.鈥�
Odorless smoke is still harmful smoke
Like ozone, smoke poses numerous health risks because of tiny particles that can enter the lungs. It鈥檚 especially bad for people with respiratory conditions like asthma and COPD. High air pollution levels have also been linked to , cardiovascular diseases and such as Alzheimer鈥檚.
Emily Fischer, an atmospheric science professor at Colorado State University, said those health risks exist even if you can鈥檛 smell the smoke.
鈥淲ildfire smoke, once it鈥檚 more than a day old, the compounds that you smell are gone,鈥� she said. 鈥淪o your nose is no longer a good tool for assessing whether we are being impacted by smoke here in the Front Range.鈥�
That鈥檚 why Fischer says everyone should check the air quality index, or AQI, before going outside, just like they would check the weather.
鈥淲e have two pollutants of concern here that you can check data daily: ozone and fine particulate matter,鈥� she said. 鈥淚 make decisions for my family living on the Front Range, especially my kids, their outdoor activities, based on that data.鈥�
For Fischer, an AQI in the orange to light red region means no afternoon exercise and limited outside time for her children. When both ozone and particulate matter levels are high, she said she鈥檚 even more conservative.
鈥淭hat鈥檚 a lot to be breathing in,鈥� said Fischer. 鈥淎nd we just don鈥檛 understand the health effects of mixtures very well.鈥�
Measuring air quality is expensive, difficult for small communities
Obtaining a precise AQI measurement can be hard to do in smaller communities. Ben Crawford, an environmental science professor at the University of Colorado Denver, said Colorado determines AQI with specific regulatory stations.
鈥淭hey look like trailers, and they鈥檙e full of instruments to measure air pollution,鈥� he said. 鈥淓ach one of these instruments can cost tens of thousands of dollars, and each one of these trailers to measure a whole bunch of different air pollution measurements can cost hundreds of thousands of dollars.鈥�
That鈥檚 why there aren鈥檛 many in the state. The stations that do exist only cover areas with long-term pollution issues, like cities.
鈥淏ut when we have these big events like a wildfire, we suddenly can have air pollution and poor air quality in areas where normally things are pretty good,鈥� said Crawford.
Without nearby expensive regulatory stations, small communities need to find other ways to determine the AQI. Otherwise, residents won鈥檛 have the necessary information to make decisions about their own health.
To address that need, Crawford and his team created a low-cost sensor network to monitor air pollution. While cheaper, the sensors are also less accurate. They also need to be calibrated to work correctly. The scientists tested them on the air pollution from a volcanic eruption in Hawaii.
鈥淭hese low-cost sensors, they work,鈥� Crawford said. 鈥淎nd they can be part of a solution to monitor air quality, especially during these kinds of extreme events.鈥�
Because of its location in the middle of the ocean, Hawaii was an almost pristine test environment. Crawford said they鈥檒l need to adapt the sensors for ozone and wildfire smoke.
鈥淗ere in Colorado, in the mountains, it鈥檚 going to be more complex,鈥� he said. 鈥淚t鈥檚 more chemically complex, it鈥檚 more meteorologically complex, and fire behavior can be much more complex as well.鈥�
As ozone levels remain high and wildfires grow in intensity, measuring and predicting air quality inside and outside of cities will become even more important. Crawford said the more tools we can develop now to help people make healthy decisions, the better.
