Newsroom | MAG Matters: You Can Help Improve the Air You Breathe By Taking Steps to Reduce Ozone

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New “MAG Matters” episode focuses on what tighter ozone standards mean for Maricopa and Pinal counties. It may be time to focus on unseen ground level ozone.

New “MAG Matters” episode focuses on what tighter ozone standards mean for Maricopa and Pinal counties

MAG Matters, Air Quality, Environment

When you hear the word ozone, what comes to mind? Most people immediately think of the ozone layer. But with our region recently moving up the severity ladder in terms of ozone pollution, it may be time to focus on unseen ground level ozone.

“Ozone is a challenge. Ozone is a gas, and you can’t see it, you can’t smell it, it is odorless, and it is comprised of three oxygen molecules,” Maricopa County Air Quality Department Director Phil McNeely said in a recent interview for the “MAG Matters” video series. “I am sure everyone has heard of the ozone layer. You would say, ‘that’s a good thing, isn’t it’? We are not talking about the ozone layer; we are talking about ground-level ozone,” McNeely says.

Ozone Emissions Are a Man-Made Problem

McNeely says the challenge is that ozone pollution is a man-made problem. That pollution includes vehicle emissions, evaporating fuel at gas stations, paint cans, machine shops, and dry cleaners. When those emissions combine with each other and sunlight, the result is ground-level ozone.

“The challenge with that is, when you breathe ozone, it’s not good for you. It can irritate your lungs if you are exposed to it for years on end, and it can cause lung damage; if you have a preexisting condition, it can trigger an asthma attack. Because of this, the EPA regulates ozone,” McNeely explains in the interview with MAG Director Eric Anderson.

New EPA Designation

When a region is found to be in nonattainment of federal air quality standards, it is classified on a rising level of severity that begins with marginal and goes up to moderate, serious, or severe. Recently, the Environmental Protection Agency (EPA) changed the designation status of our region from marginal to moderate nonattainment.

“We had a new standard in 2015 that went from 75 parts per billion to 70 parts per billion,” McNeely says. “Seventy-five is currently what we see at the monitors, and we didn’t make the 70 (ppb) standard in the time frame they gave us,” McNeely.

Each more stringent nonattainment classification increases regulatory requirements, impacting drivers and businesses. McNeely says that is why it is important for not just industry but also individuals to do what they can to reduce pollution.

Cars idling on freeway at standstill

The Issue with Idling

Ozone forms when two key pollutants, nitrogen oxides (NOx) and volatile organic compounds (VOCs) “cook” in the sun. These pollutants are precursors to ozone formation, meaning they must be present in the air for ozone to form. While about 25 percent of NOx comes from stationary sources, a full 50 percent comes from tailpipes.

When you let your car idle, it can contribute to unhealthy air.

“When you sit through a drive-thru, or you pick up your child (from school) and you leave the car running, that accounts for three and a half tons of NOx emissions every day, which is very significant. It accounts for about six percent of traffic emissions,” said McNeely.

Cars idling in drive-thru lane

Potential Business Impacts

While more protective of public health, the new ozone designation could pose additional challenges for the region in meeting the most recent, more stringent ozone standard. The moderate nonattainment area classification requires new actions and measures, including:

  • New control measures to reduce the types of emissions that create ozone.
  • Emission offset requirement for new, large facilities locating in the nonattainment area and major expansions to large, existing facilities, which are required to offset every ton of emissions by 1.15 tons.
  • Contingency measures (i.e., measures to be deployed if the nonattainment area does not meet yearly emission reduction milestones).
  • Potential emission controls for intrastate facilities or other emission sources located outside the Phoenix-Mesa nonattainment area.

McNeely says the EPA requires Maricopa County to review its rules, which could lead to more stringent business guidelines.

“We don’t want to stymie businesses by putting more restrictions on them when they are not really the cause of the problem,” McNeely says. Instead, the department hopes Valley residents will commit to at least one day of carpooling or using alternative modes of transportation.

Reduce ozone by using public transportation, telecommute, and car pool

Other steps every resident can take to reduce ozone include:

  • Reduce the number of miles driven. Drive as little as possible: carpool, use public transit, or telecommute.  For information on transportation alternatives, visit Valley Metro at
  • Fuel your vehicle after dark or during cooler evening hours.
  • Use low-VOC (Volatile Organic Compounds) or water-based paints, stains, finishes, and paint strippers.
  • Delay big painting projects until high pollution advisories or health watches have passed.
  • Make sure containers of household cleaners, garage and yard chemicals, and other solvents are sealed properly to prevent vapors from evaporating into the air.
  • Eliminate wood burning in fireplaces, stoves, chimineas, and outdoor fire pits.
  • Avoid using leaf blowers.
  • Conserve electricity.
  • Make the switch from gasoline to electric or battery powered lawn and garden equipment. For information on the Mowing Down Pollution and Commercial Lawn and Garden Programs, visit

Published February 10, 2023