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For ozone (O 3), the guidelines suggest values no higher than 100 μg/m 3 for an 8-hour mean and 60 μg/m 3 peak season mean. [2] For nitrogen dioxide (NO 2), the guidelines set 10 μg/m 3 for the annual mean or 25 μg/m 3 for a 24-hours mean. [2] For sulfur dioxide (SO 2), the guidelines stipulate concentrations not exceeding 40 μg/m 3 24 ...
Levels of ground-level ozone, designated as one of six common air pollutants by the U.S. Environmental Protection Agency, can rise when compounded by heat and sunlight.
Ground-level ozone (O 3), also known as surface-level ozone and tropospheric ozone, is a trace gas in the troposphere (the lowest level of the Earth's atmosphere), with an average concentration of 20–30 parts per billion by volume (ppbv), with close to 100 ppbv in polluted areas.
In April 2023, the EPA finalized its "Good Neighbor Plan", which phases in tighter standards for NO x, using a cap and trade system during the summer "ozone season". This is intended to reduce ground-level ozone in non-attainment areas downwind of industrial sources like power plants, incinerators, and industrial furnaces, often in other states ...
It’s been No. 1 for ozone pollution for decades, Pruitt said. With the wildfires now on top of that, the air quality index has been sitting at “unhealthy” levels for many parts of Southern ...
If ozone levels are unhealthy, plan outdoor activities for the morning or evening, when ozone levels are typically lower. If there is wildfire smoke, avoid activities that could create more fine ...
The ozone at ground level is primarily from fossil fuel precursors, but methane is a natural precursor, and the very low natural background level of ozone at ground level is considered safe. This section examines the health impacts of fossil fuel burning, which raises ground level ozone far above background levels.
Clawson said the ozone levels peak between 3 p.m. and 7 p.m., which is why MARC warns people — especially children or those with respiratory conditions — to reduce or reschedule plans for any ...