Fine particles also form when gasses such as nitrogen oxides (NOx) and volatile organic compounds (VOCs) react and condense in the atmosphere.These gasses come from the same sources noted above.But in the summer it is usually associated with pollution episodes involving haze and participates in chemical reactions that lead to haze-forming particles.Medium or high concentrations of ozone are a good indicator that poor visibility conditions are due to pollution.During the summer, ozone can be unhealthy for several days in a row.Because it is an invisible gas, ozone does not directly affect visibility.Most haze is caused by coal-fired emissions from power plants.
An exception to this rule would be during periods of fog.
However, pollution can cause poor visibility without necessarily leading to high ozone concentrations.
For information on these pollutants and their effects on health, see the health effects page.
Note that some CAMNET sites do not measure all of these variables.
Fine particles, also called particulate matter (PM), are a mix of microscopic solids and liquids.
To learn more about the pollutants and meteorological conditions, please read on.