If you regularly wake up in the morning with your jaw aching, a visit to the dentist may be in order. But you may want to talk with your doctor, as well. The chronic clenching or grinding of teeth is called sleep bruxism. According to one study, this is a common sleep disorder. Sleep bruxism can do significant damage to your mouth. But, according to the study's authors, it also may have other consequences. Participants with sleep bruxism had a higher risk for anxiety, nightmares, loud snoring, daytime sleepiness, and sleep apnea - a condition in which sufferers stop breathing for periods while asleep.
Chest, Vol. 119, No. 1

Being outside when pollution is bad can harm your respiratory health. According to one study of 772 people, it may raise your heart risks, too. Being exposed to high levels of pollution was linked to a higher risk of suffering a heart attack within several hours - or even days - after exposure.
Circulation, Vol. 103, No. 23