There\u2019s also the physiological effect of heat itself on our breathing. \u201cHeat may also destabilize breathing control, increase fluid retention, and promote dehydration, all of which can make the upper airway more collapsible and increase the likelihood of sleep apnea,\u201d says Lucia Pinilla, another researcher at Flinders University investigating the subject.<\/p>\n
At the same time, sleep apnea is already expected to become a growing problem for those living in cities, due to the chronic impact of air pollution on nighttime breathing, something which is only predicted to get worse. Last year, Hong Kong researchers led a study<\/a> where they found that both short and long-term exposure to PM2.5 particles\u2014tiny airborne particles, less than 2.5 micrometers wide, which are generated by sources such as vehicle exhausts, factory emissions, and wildfires and can penetrate deep into the lungs and bloodstream\u2014makes sleep apnea more likely.<\/p>\n Others have shown that the same is true for nitrogen dioxide<\/a>, a reddish brown gas released into the air from exhausts, power plants and other industrial facilities, while exposure to pollution also worsens symptoms<\/a> for people with existing sleep apnea.<\/p>\n \u201cObstructive sleep apnea occurs when the upper airway becomes unstable and collapses during sleep,\u201d says Martino Pengo, associate professor from the University of Milano-Bicocca who studies the subject. \u201cAir pollutants can increase this instability by irritating the tissues of the throat, making the airway narrower and more prone to collapse when muscle tone naturally falls at night. Nitrogen dioxide is a strong airway irritant and may promote local inflammation that can fragment sleep and destabilize breathing.\u201d<\/p>\n While concerning, such research also points to possible ways of mitigating risk. Martha Billings, professor of medicine in the University of Washington\u2019s division of pulmonary, critical care, and sleep medicine advises using indoor air filtering devices if online air quality databases show that your city ranks particularly poorly. \u201cI would recommend it especially if the air quality index is greater than 200 as can happen with forest fires or other stagnant air,\u201d she says.<\/p>\n