East-central Iowa is under an Air Quality Alert until Wednesday morning. The Iowa DNR says elevated levels of fine particle pollution were recorded across the area Tuesday morning. The EPA’s 24-hour health threshold for fine particles is 35 micrograms per cubic meter. On Tuesday morning, they registered at about 41 micrograms. Fine particles are emitted by vehicle traffic and other combustion sources. Stagnant air masses don’t allow fine particles to disperse, so pollutant levels rise. The DNR recommends that children, the elderly and anyone with respiratory or heart disease limit their time outdoors until conditions improve. The Air Quality Alert is in effect until 10 am Wednesday for Delaware County and the surrounding counties. A cold air mass with westerly winds is expected to clear the air and improve conditions Wednesday morning.