Mongabay: Harmful ozone-causing emissions are on the rise again, a new study has found. Naturally occurring ozone in the upper atmosphere is good, protecting us from the suns ultra-violet rays. But ground-level ozone, formed from reactions between nitrogen oxides and non-methane hydrocarbons can be very damaging, triggering a number of health problems such as asthma and lung diseases. Ethane, a non-methane hydrocarbon, is a major precursor of ground-level ozone. Ethane emissions peaked in 1970, but decreased...