The organization's State of the Air report ranks Houston as the 7th most polluted city in the nation for smog.
Harris County comes in 10th on the list of counties with the worst air quality.
Adrian Shelley is with Air Alliance Houston.
"We are issuing, say, 30 to 40 ozone warnings every year, and those are days in which the ozone levels are getting high enough to be of concern to the general public."
Shelley says one of the main sources of dirty air in Houston is cars, even though vehicle engines are becoming more fuel efficient.
"The volume of vehicles on our roads continues to increase, and that could potentially offset reductions that we get because of fuel efficiency."
Shelley says there also needs to be tougher requirements for plants and refineries to make sure they're giving accurate information as to what's going into the air.