The Wisconsin DNR has issued an Air Quality Watch for southeast Wisconsin Wednesday into Thursday morning.    You may have noticed this type of thing issued in your area at various times the past few years.   We see it more often in the summer when we have a humid, stagnant weather pattern without much wind.   In winter, it occurrs when we have had a prolonged period with a low level temperature inversion which tends to trap the air and pollutants in the lowest few thousand feet of the atmosphere.  They do this when unhealthy levels of ozone and particulate matter are expected.   The technical discussion of such matters listed below is taken directly from their website.

Groups that are most sensitive to ozone and PM2.5 include:

• Active children who spend much of their time outdoors
• Active adults who spend much of their time outdoors
• People with asthma or other respiratory diseases
• People with heart disease (PM2.5 sensitivity only)
• Older adults (PM2.5 sensitivity only)

At high levels, everyone should be concerned about ozone and PM2.5 exposure affecting their respiratory health. Ozone and PM2.5 can affect human health in many ways:

• Irritate respiratory systems and cause coughing and difficulty breathing
• Reduce lung function
• Aggravate asthma
• Cause permanent lung damage
• Aggravate or cause chronic lung diseases such as emphysema and bronchitis
• Reduce the immune system’s ability to fight off bacterial infections in the respiratory system
• Irregular heartbeat (PM2.5 only)
• Nonfatal heart attacks (PM2.5 only)
• Premature death in people with heart or lung disease (PM2.5 only)

Environmental Health Impacts

• Ground level ozone and particle pollution are major components of smog, which reduces visibility in addition to affecting human health.
• Ground level ozone and particle pollution damage non-living things. Ozone affects rubber, textiles, and coatings like paint and dyes. Particle pollution can damage statues, monuments, and buildings made of stone and other materials.
• Ozone injures plant leaves and slows photosynthesis, the process by which plants make their food. Ozone damage leads to reduced plant growth and survival and increased susceptibility to diseases, pests, and drought. Leaf discoloration and spots are visible symptoms of severe ozone stress. Ozone impacts the production of agricultural crops and commercial timber and also diminishes the aesthetic value of natural and landscaped vegetation.
• Fine particle pollution is often acidic, causing acid rain and making lakes and streams acidic. Deposition of nitrogen-containing particles may change the nutrient balance in lakes and rivers, affecting the diversity of ecosystems or damaging forests or crops

Ozone

• Ozone (O₃) is a colorless gas found both in the Earth’s upper atmosphere and at ground level. Ozone can be good or bad, depending on where it is found.
• Ozone occurs naturally in the Earth’s upper atmosphere, 10 to 30 miles above the Earth’s surface, forming a layer that shields life on Earth from the sun’s harmful ultraviolet rays. Because of this protection, stratospheric ozone is sometimes called “good ozone.”
• While stratospheric ozone protects us, at ground-level, where we inhale it, ozone is harmful to health. Ozone is created by a chemical reaction between nitrogen oxides (NO_x) and volatile organic compounds (VOCs) in the presence of heat and sunlight.
• The highest ozone levels in Wisconsin typically occur from mid-May to mid-September, especially in hot hazy weather with southerly winds.
• On March 12, 2008, EPA announced that the 8-hour ozone standard had been lowered to 75 ppb from 85 ppb in response to better data about health impacts.

Particle Pollution

• Particle pollution is composed of solid particles or liquid droplets that are suspended in air.
• There are two size ranges for particle pollution that are a concern in Wisconsin: coarse particles (PM10) have a diameter of 10 micrometers or less, and fine particles (PM2.5) have a diameter of 2.5 micrometers or less. For reference, the average human hair is 70 micrometers in diameter, 30 times larger than the largest fine particle.
• PM2.5 is more closely regulated than PM10 because of greater health concerns as they can imbed deeper in the lungs, even in the tiniest air sacs.
• In Wisconsin, PM2.5 levels typically peak in winter but concentrations can also be high in summer.
• In October 2006, EPA lowered the 24-hour PM2.5 standard to 35 micrograms per cubic meter (µg/m³) from 65 µg/m³.

They have a series of monitoring stations set up around Wisconsin to keep track of this stuff.  Go here if you would like to check it out.  http://dnrmaps.wisconsin.gov/imf/imf.jsp?site=wisards

When air quality watches or advisories are in effect, the DNR recommends people refrain from burning and use your vehicles and other gas and diesel fueled devices as little as possible.

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