Area residents afflicted by asthma and other respiratory issues are advised to stay indoors until the heat wave passes.
The Southeast Michigan Council of Governments has designated Wednesday as another Ozone Action day for Monroe County and six other counties in its Metro Detroit district, its sixth of the summer and third this week.
Toledo Environmental Services also said Tuesday that "precautionary measures should be taken by sensitive groups" through at least Thursday.
The National Weather Service forecasts 90-plus-degree days through the weekend with tomorrow being the worst, as heat-index values are estimated to reach 109 degrees.
Ozone Action days are smog alerts that regional governmental agencies declare when atmospheric and weather conditions are most likely to make breathing more difficult.
Ground-level ozone forms what in commonly known as smog.
Toledo disbanded its Ozone Action program a few years ago in favor of an advisory system it believes is easier to understand.
Advisories are required by the U.S. Environmental Protection Agency to help brace the public for dealing with the potential of short-term spikes in smog.
Residents are encouraged to make adjustments when the smog levels are high, such as waiting until after 6 p.m. to refuel automobiles and not "topping" them off with fuel, keeping tires properly inflated, carpooling, taking mass transit, and refraining from using lawn mowers and other gas-powered machinery during peak daytime hours.
The elderly, infants, and toddlers are most susceptible to heat and heat-related illness, officials said.
Thirteen Toledo-area senior centers and one in Bowling Green are offering air-conditioned cooling centers for seniors and others who need a break from the heat.
Along those lines, Manor Elementary School in Monroe will not hold its summer school program tomorrow because of the heat. The classes are to resume Monday.
The Manor postponement does not affect summer school classes at Monroe Middle School and Monroe High School.
As well, the Brown Bag Summer Concert Series at the Toledo-Lucas County Library's Main Library, 325 Michigan St., is being moved inside Wednesday.
The concert will be held from 12:15 to 1:15 p.m., but the blues, jazz and R & B concert featuring Tom Turner and Slow Burn will be in the Huntington Meeting Room. Seating will be provided.
Additional information on ozone action is at semcog.org (look for Ozone Action under Hot Topics on the home page) or at 800-66-33-AIR.
Residents can also request email notification of Ozone Action days by sending an email to email@example.com and putting "Notification" in the subject line.
SEMCOG said its Ozone Action program also is on Facebook and Twitter.
Northwest Ohio residents are encouraged to call Toledo environmental services at 419-936-3015.