The Regional Transportation District spent more than $15 million this summer on free rides with the goal of cleaner air along the Front Range, and a first-of-its-kind study shows more than 6 million pounds of greenhouse gas emissions were cut during the Zero Fare for Better Air promotion.

However, 6 million pounds of greenhouse gas emissions is just a bite-sized chunk of the air pollution Colorado wants to reduce. The state’s Greenhouse Gas Pollution Reduction Roadmap calls for a reduction of 12.7 million tons in annual transportation emissions by 2030.

People who chose to ride RTD’s buses and trains in July and August likely reduced the number of vehicle miles traveled by 145,393 a day, or 9 million miles over the course of two months, according to the Zero Fare for Better Air 2023 Evaluation report released Thursday.

By not traveling all those miles, drivers did not contribute to the pollutants that combine on hot summer days to create ground-level ozone.

The Regional Air Quality Council, which is tasked with finding ways to cut air pollution, helped RTD officials figure out how much was reduced during the two-month program. The air council used the modeling formula that federal officials use to measure greenhouse gas and other emissions created by transportation.

The air council’s study concluded that 2,583 pounds of volatile organic compounds and 2,235 pounds of nitrous oxide were reduced during the two months, according to the report.

Eliminating greenhouse gas emissions is crucial in the nine-county region surrounding Denver because the area is not in compliance with federal air quality standards. Metro Denver and the northern Front Range are listed in serious violation of ozone standards by the Environmental Protection Agency and are under pressure to improve conditions.

Poor air quality is dangerous for humans, especially children, the elderly and people who suffer from chronic lung conditions such as asthma. The pollution from cars, trucks and other gas-powered vehicles also creates a brown haze that blankets the area, and transportation-related pollution is one of the largest contributors to climate change and global warming.

Mike Silverstein, the air council’s executive director, said in a news release that increased use of public transportation reduces fuel production by the oil and gas industry, which also contributes to air pollution.

“RTD’s Zero Fare for Better Air initiative helps reduce both our fossil fuel use and the demand for its production, making a positive impact on our local air quality during peak ozone season,” Silverstein said.

The Zero Fare for Better Air evaluation also included statistics on how increased ridership impacted crime, including drug use, vandalism and assaults, on RTD property. Train operators and bus drivers feared security problems would undercut the program and they complained to RTD’s elected board just before the program launched.

There were fewer arrests and narcotics usage decreased during the Zero Fare period when compared to the average number of incidents during the rest of the year, the evaluation said. However, there were increases in criminal mischief/property damage reports, assaults, trespassing and biohazard incidents.

RTD also reported a jump in security incidents —  interactions with people fighting or otherwise disorderly, sick or impaired — during the two-month free fare period. In June, RTD recorded 601 security incidents but that number rose to 750 in July and 914 in August. In September, 737 security incidents were reported.

The transit district noted that it is difficult to make year-to-year comparisons on crime during the Zero Fare program because it recently changed how it accounts for crime on its buses and trains.

This year, the free ridership program expanded to two months rather than one and that longer period resulted in a 10% increase in ridership, with more than 6 million people taking advantage of the free transportation.

The program cost RTD $15.2 million in lost fares and other expenses such as marketing and surveys that help understand how the program impacts employees and customers. The Colorado Energy Office reimbursed RTD $13.9 million to help offset the lost fares, the report said.

This story was updated to correct the name of the Regional Air Quality Council executive director.

Get more Colorado news by signing up for our Mile High Roundup email newsletter.