The January 2015 legislative season opened with a bang as Utah witnessed the largest bipartisan anti-air pollution protest in its history. Speakers ranged from Republican Speaker of the House Greg Hughes to Utah Moms for Clean Air founder Cherise Udell. The legislative session ended with a whimper, however, as no significant clean-air legislation was even brought forward for a vote. It seems that the money-infused free speech of large polluters silenced the voices of thousands of citizens. Even something as simple as banning wood burning during red air days failed to pass.

As a new citizen to Utah and a mom, I decided to try to figure out what is going on with air pollution in this area. And the best way to learn about the air quality objectively is to exam the available data. Data reveal the past and help us plan for the future. Using the Environmental Protection Agency's Air Quality Index (AQI), I traced the monthly AQI and levels of pollutants in Salt Lake City over the past 35 years. In order to discover the developing trends of the changing data, a Web-based visualization was created. The results are surprising and illuminating.

There is a significant decline of the overall yearly AQI from 1980 to 1997. Contrary to popular perceptions, the air quality in Salt Lake City has become steadily worse in the last decade. After 1997, the air quality in Salt Lake has remained at roughly the same health level. 2014 was the only “green-air” year we have had in the past 35 years (Green means “good and healthy” air according to the AQI levels and corresponding colors standardized by EPA). However, there is too little evidence to show the causes of this improvement of air quality besides the warm and windy weather we have had.

The pollution composition is also visualized on a yearly basis, using the yearly averaged percentage levels of the five major air pollutants (ground-level ozone, particle pollution, carbon monoxide, sulfur dioxide and nitrogen dioxide). From the percentage visualization, it is obvious that the air pollution composition has changed over the last decades. The major pollutant in recent years is ground-level ozone, PM2.5 and No2, as opposed to SO2 in the 1980s and early 1990s. There has been a noticeable decline of SO2 since the early 1990s. This corresponds directly to the overall air quality improvement in the yearly AQI chart.

So, how do we explain these results? The clearest answer is that government intervention in the form of laws actually works. In the 1950s and 1960s as America's economy boomed, the pollution also boomed until cities were shrouded in fog and rivers actually caught fire in Boston and Cleveland. The pollution crisis inspired Earth Day in 1970, and motivated President Richard Nixon’s White House to push for several anti-pollution measures, including the Clean Air Act, the Water Pollution Control Act and the establishment of the Environmental Protection Agency. In the 1980s the Toxic Release Inventory (TRI) was established allowing everyone to get a big picture of the pollutants being released across the nation. For example, even today Utah is drenched in the corporate release of pollutants, with the latest TRI ranking Utah No. 2 for toxic releases.

Anti-pollution legislation had huge impacts across America resulting in the cleaner air and cleaner water that we enjoy today. My visualization of pollution in Salt Lake Valley clearly demonstrates this. Thankfully, the air we are breathing is better today than it was in 1980. My graph, however, more soberingly reveals that the absence of increasingly strong anti-pollution legislation has stalled progress in cleaning our air. Since 1997, many of the pollutants in our air have remained relatively constant. Some pollutants are worse, including ozone and PM2.5.

This lack of progress is what makes the 2015 legislative session so disappointing. Living daily with smoggy air and choking inversions makes us all want better air for ourselves and our children. After 17 years of improving air, we have now witnessed 17 years of stagnation. As the Salt Lake Valley faces growing pollution pressures from both industry and population growth, now is the time for stronger and smarter legislation to combat our air pollution crisis.

Yvette Shen is a faculty member at the University of Utah in the Department of Communication.