Tag Archives: ozone

KC escapes sunny, hot weekend without an Ozone Alert

This weekend — despite the heat and sunlight — we didn’t exceed the ozone standard. Today we have a guest post from our meteorology consulting team at Weather or Not, who provide the SkyCast during the ozone season, to explain why.

Sunshine, heat and southerly winds are typical triggers for high concentrations of ground level ozone. So why is it that Kansas Citians basked in the sunshine, felt the heat and southerly winds but didn’t see an Ozone Alert this weekend (June 11 and 12)?

Factors such as cloud cover, lower traffic on the weekends, rain potential and upwind pollution all played their part.

Cloud cover played a pivotal role in limiting local production of ozone. Sun is a key ingredient in the formation ozone, so when puffy cumulus clouds begin to build, ozone production either stalls or decreases. The hour of each day that the puffy cumulus clouds were building was the exact same hour that ozone monitors peaked. Since the EPA ozone standard is based on a running eight-hour average, the “fair weather” clouds helped to keep ozone levels from climbing too high.

Sunday’s scattered showers and thunderstorms also helped decrease ozone values. Thickly clouded, rainy afternoons are an environment that can stunt ozone production and keep levels within clean air limits.

Weekend traffic helped. Fewer cars on the road helped to minimize local ozone production Saturday and Sunday. During the weekdays, we have two peak travel periods (morning and evening) that can increase dirty air. On the weekend we don’t have rush hour traffic, which limits pollution levels that could lead to increased ozone production.

We got a little help from our friends. Our upwind pollution potential for the weekend originated from Dallas, Tulsa and Oklahoma City. Their ozone levels stayed at high green to low yellow values (Air Quality Index (AQI) values in the upper 40s to low 50s). Often when their levels are high for a few days, southerly winds will transport those high ozone concentrations into the Kansas City area. That didn’t happen this weekend.

While close monitoring of the Ozone Alert potential was necessary this weekend, Mother Nature did her part to keep ozone in check in Kansas City.

And you helped, too, if you limited driving and other emission-producing activities.

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Another quiet ozone season thanks to cool mid-summer temperatures

Ozone Season 2014

By Doug Norsby, Air Quality Planner III

Again this year, a wet spring followed by mild summer weather provided a welcome relief from the high ozone levels seen during 2011 and 2012. The 2014 ozone season began with normal temperatures and rainfall in April and May, followed by above-average rainfall in early June and below-average temperatures in July, resulting in a relatively good ozone season. MARC issued 46 yellow SkyCasts and two orange Ozone Alerts for the Kansas City region’s air quality maintenance area. The low number of yellow and orange SkyCasts was almost identical to last year’s numbers.

The SkyCast is issued daily during ozone season (April 1–Oct. 31) and corresponds with the Air Quality Index (AQI), a public information tool that associates colors and health messages with ranges of air pollutant concentrations. This season, only two days exceeded the standard set by the U.S. Environmental Protection Agency to protect public health.

At the conclusion of the 2014 season, ozone monitor readings appear to show that the Kansas City region is no longer violating the ozone standard for the first time since 2010. However, federal law requires EPA to periodically review air quality standards to ensure that they provide adequate health and environmental protection, and to update those standards as necessary. EPA is currently in the process of reviewing the ozone standard and is expected to propose a new standard in December. If it is tightened, it is likely that the recent lower readings will still fall in the range that is considered to be unhealthy.

The region continues to employ voluntary strategies to reduce ozone-forming and greenhouse gas emissions, and our participation in the EPA’s Ozone Advance program and implementation of our award-winning Clean Air Action Plan (CAAP) both leverage local community actions to reduce potential federally mandated and state-imposed regulations.

For more information, contact the MARC Air Quality program.

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Ozone season is underway!

air_quality_indexWe had a long, persistent winter, but the days are finally getting longer and temperatures are starting to rise. However, warmer temperatures bring the chance for more ozone pollution. That’s why the period from April 1 to Oct. 31 is known as “ozone season.”

Ozone pollution, also known as smog, is formed when emissions from man-made sources react in heat and sunlight. Ozone is harmful for everyone; it can cause coughing, wheezing and difficulty breathing. But for children or people with breathing or heart problems, it can be dangerous.

So how do you know when ozone pollution may be a problem?

Check the SkyCast! The SkyCast is the daily, regional air quality forecast issued by the MARC Air Quality Program. You’ll see “Ozone Alerts” when our air is forecast to be poor. There are many ways you can get updates:

The most important thing to remember about ozone pollution is that you can help reduce it. Throughout ozone season we’ll post tips for helping our air, so be sure to check back for information on the small steps you can take to reduce pollution.

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2013 Ozone Season Summary: a quiet season thanks to a late spring and summer

AirQ Season Summary GraphThis ozone season, MARC issued 45 yellow SkyCasts and four orange Ozone Alerts for the Kansas City region’s air quality maintenance area. The cool, wet spring and late arrival of summer weather provided a welcome relief from high ozone levels seen over the last two years and contributed to the significantly lower number of yellow and orange SkyCasts.

The SkyCast is issued daily during ozone season (April 1–Oct. 31) and corresponds with the Air Quality Index (AQI), a public information tool that associates colors and health messages with ranges of air pollutant concentrations. This season, only two days exceeded the eight-hour ozone concentration standard of 75 parts-per-billion (ppb) set by the U.S. Environmental Protection Agency to protect public health.

Over the last five years, with the exception of 2010, the maximum ozone values in the Kansas City region hovered just above the 75 ppb standard (see graph). The next required review of the ozone standard is set for 2013. When the EPA completes its review, the region’s air quality status will likely be reassessed based on data collected during the three most recent ozone seasons — 2011, 2012 and 2013.

Another factor in the reassessment is that the EPA is expected to lower the ozone concentration standard from 75 ppb to somewhere between 60 and 70 ppb. Because of this, we expect our region may soon be designated as “nonattainment,” triggering changes to future regulatory requirements. In anticipation of these changes, the region has updated its award-winning Clean Air Action Plan (CAAP) annually and has signed on to the EPA’s Ozone Advance program. These proactive steps will give the region some ability to leverage the CAAP’s voluntary strategies to reduce ozone-forming and greenhouse gas emissions in the Kansas City region and may reduce the need for imposed regulations.

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Air Quality Index: the what, how and why

The What

An Ozone Alert is issued when ozone levels are expected to be in the “orange” range or higher on the Air Quality Index (AQI). But what does that really mean, and why does the AQI stay the same even when the National Ambient Air Quality Standards (NAAQS) have changed over the years?

The AQI is a health-based scale meant to represent how healthy the air is each day. In general we only hear about the AQI during ozone season (April 1–Oct.31 of each year) in the Kansas City area, but the AQI is actually calculated year-round. The U.S. Environmental Protection Agency (EPA) calculates an AQI for five pollutants:

air_quality_index

  1. carbon monoxide
  2. nitrogen dioxide
  3. ozone
  4. particulate matter
  5. sulfur oxides

The How

The AQI also alerts the public about which pollutant is expected to have the highest concentrations that day. As I mentioned above, ozone is Kansas City’s main pollutant, but on days where our air is impacted by fire (i.e., wildfires or rangeland burning) or in areas where there is a high percentage of residential wood-burning furnaces, particulate matter can be the main pollutant. There is only one AQI issued for a metropolitan area at a time, so while a cold day in January will have ozone levels well into the green category, particulate matter could cause a city’s AQI to creep into the yellow range. This doesn’t happen often in Kansas City, but it is not unheard of. You can always find the AQI at the AirNow website, and during ozone season on the MARC website (as well as Twitter, Facebook or your own email!)

The Why

Why does the AQI stay the same when the NAAQS (pronounced “nacks”) change? The numbers on the AQI scale correspond to the current national standards for each pollutant. For example, the current ozone standard is 75 parts per billion (ppb). If a daily air quality forecast indicates that the ozone level is expected to exceed 75ppb averaged over an eight-hour period, the AQI would be 101 or higher. That’s when we’ll issue an Ozone Alert to call attention to and help everyone understand the health impacts of poor air quality on that day. Last year’s summer was particularly hot and dry, and in Kansas City we saw 29 days that exceeded 75ppb. Particulate matter also has a level that is considered unhealthy (higher than 12 micrograms per cubic meter on an annual basis) and that level would also be indicated by an AQI of 101 or higher.

By using a consistent, color-based scale for all pollutants, it’s easier for us to communicate whether the air is healthy or not. The AQI is your one-stop shop for health-based air quality information. Still have questions? Email us at AirQ@marc.org!

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