2012 was the hottest year on record, and climatologists watched heat records fall right and left. And while you may have noticed daffodils blooming in February or stayed glued to your TV watching the devastation fueled by Superstorm Sandy, you probably didn’t notice the increasingly polluted air outside your front door. Linda Marsa, investigative journalist and author of the new book Fevered: Why a Hotter Planet Will Hurt Our Health—And How We Can Save Ourselves, says that bad air is perhaps the most insidious but underappreciated health problem associated with a warmer world. “It’s sort of like the frog in the pot of boiling water,” she told Rodale News in an interview. “You don’t notice it, but the air is gradually getting worse and worse and worse.” As temperatures warm, she adds, the heat reacts with pollution in the air to cause even more toxic compounds that you can’t see. “As temperatures rise and more pollutants are dumped into the atmosphere, the plume of that toxic cloud will spread like ink on a blotter, covering more land under a suffocating carbon canopy,” she writes. Experts she interviewed have linked bad air quality to as many as 1,000 excess deaths across the country each year. Here are five of the biggest health problems associated with dirty air:


  1. Ozone Smog.
 Glance outside on a hot day in an inner city and the sky probably has that hazy orange glow that lets you know something’s afoul in the air. But it’s more than just haze. As temperatures rise, Marsa writes, the heat “cooks” all the pollution emitted by cars, trucks, power plants, and the like, converting it into lung-damaging ozone, the main trigger for asthma attacks and allergies, as well as respiratory diseases like pneumonia and chronic obstructive pulmonary disease. “When the air heats up,” she writes, “more ozone is produced, and more ozone in turn traps more heat, exacerbating the urban heat island effect and creating a vicious cycle.”
  2. Ultra-Toxic Particulate Matter 
Heat and sunlight don’t just react with pollution to create ozone. The same chemical reaction that creates ozone, Marsa uncovered, produces chemical compounds that create particulate matter in the air. The largest of these particles, known as PM10, attach themselves to dust that, when inhaled, attaches to the interior of your lungs and creates mucus that triggers a persistent cough. Even smaller particles, known as PM2.5, linger in smoke and chemical fumes and are far more toxic. Once inhaled, they get lodged deep inside your lungs and cause constant irritation that leads to heart problems and cancer and, research is finding, can infiltrate your brain and cause memory and concentration problems. (Though not all these problems are reversible, science has uncovered 6 Ways to Prevent Air Pollution from Harming Your Heart.) 
  3. Deadly Diseases In addition to damaging your lungs and making you more susceptible to memory problems, particulate matter in the air, particularly diesel particulates spewed by trucks and factories, serves as a wonderful host for lethal fungal spores, says Marsa. One disease of particular urgency is Valley Fever, a lung disease caused by a fungus that lives in soil and is related to the mushroom family. The disease has now reached epidemic proportions, with the number of people contracting it quadrupling over the past 10 years. It kills roughly 200 people out of the 200,000 it infects every year, making it a deadlier disease than Lyme disease, West Nile virus, or even the influenza’ hh=‘1’>flu And it’s not just Valley Fever. Researchers have documented cases in which meningitis was spread via dust in the Sahara desert, and they suspect that dust has also been the source of SARS outbreaks, influenza, and other respiratory diseases.
  4. Arsenic-Laden Dust People who live outside the Valley Fever belt and outside the reach of the fungus (wind can carry fungus-laden dust up to 500 miles) aren’t entirely off the hook. Researchers from the University of Arizona are finding that droughts, which are increasing as a result of climate change, are spreading toxic dust. Here’s what happens: Heavy metals such as lead and arsenic exist naturally in soil, and their levels are compounded by metals that used to exist in pesticides and that are spewed from industrial sources, such as mines, factories, or plants that burn fossil fuels. Rainwater usually washes these metals farther underground, where they wind up in innocuous amounts in groundwater. But these researchers now worry that a persistent lack of rain, which we’re seeing in both the Southwest and in the Midwest, means that these pollutants will now be carried via dust storms, which are increasing in size, number, and frequency.
  5. More Potent Pollen There’s a reason that every allergy season is dubbed the worst allergy season ever: climate change. Though not directly tied to high temperatures on one specific day, the allergenicity of pollen has greatly increased, Marsa writes, because higher carbon dioxide concentrations act like plant food and increase the proteins responsible for allergic reactions. “Noxious weeds—as well as vines like poison ivy and kudzu—react much more strongly to higher CO2 than other types of plants,” she writes. “As a consequence, we see not only more growth, but also more virulent chemicals within the plants.”  More from Prevention:  Preventing Air Pollution In Your Home  EPA Proposes Stricter Air Pollution Regulations by 2020  City Exercisers: How Pollution Affects You