Ozone as a layer several kilometers up in the atmosphere protects living beings, including humans, from ultraviolet rays. But its accumulation at ground level can be very dangerous, Mongabay contributor Sean Mowbray explains in an article published in April. Ground-level, or tropospheric, ozone forms when methane, nitrogen oxides, carbon monoxide and volatile organic compounds react with sunlight. With Earth warming due to human-driven climate change, ozone pollution is worsening as it’s linked to higher temperatures. Ozone itself is a greenhouse gas and has contributed to around 0.2° Celsius (0.36° Fahrenheit) of current global warming, Mowbray writes. Ozone at ground level harms human health. Experts interviewed by Mowbray say the gas not only irritates the airways and can worsen underlying health issues such as asthma or chronic bronchitis; it can also affect cardiovascular and reproductive systems. Studies have found ozone exposure to be associated with low infant birth weight and gestational hypertension. Long-term exposure to ground-level ozone is also estimated to have contributed to 365,000 deaths in 2019, a figure that’s now considered to be a conservative estimate. In addition to harming human health, ozone at ground level also limits the growth of plants, reducing their ability to absorb and store carbon dioxide, says Nathan Borgford-Parnell, coordinator of the scientific advisory panel and science affairs at the Climate & Clean Air Coalition. This effectively doubles the climate impact of the gas, he adds. “Overall, we have decreased photosynthesis, growth, biomass, and yield of the plants,” Evgenios Agathokleous, a professor at the School of…This article was originally published on Mongabay