But people are not just sweating more. They’re dealing with increased levels of toxins in the air and a higher risk of contracting diseases more prevalent in warmer climes. For example, global warming causes an increase in ground-level ozone. Higher levels of heat unleash greater concentrations of this chemical, which is the key ingredient in smog. Ozone irritates eyes and diminishes lung function, especially among the young and the elderly. Excess ozone can lead to asthma attacks, bronchitis and other allergic reactions. Over the past 30 years, as the Earth has warmed, the number of Americans suffering from asthma has doubled. Climate change is also increasing the number of animals that carry disease, including fleas, ticks, mosquitos and other insects that thrive in hot weather. Mosquitoes are incubating faster, living longer and spreading to more places. The increased insect population elevates the danger of contracting illnesses like Lyme disease, which is carried by ticks. Currently, there are over 300,000 cases of Lyme disease reported in the United States every year. That’s double the figure of a quarter-century ago. The formerly tropical Zika virus has reached American shores. Experts warn that the mosquito-borne virus could march northward due to longer summers and heavy rainfall. Climate change is also putting Americans at increased risk of bacterial infection. Rising temperatures in the world’s water supplies provide a fertile environment for bacteria, parasites and other dangerous organisms. Debilitating abdominal illness could be the result.”