Thousands of residents across part of California have been advised to stay indoors as elevated levels of fine particle pollution -- known as PM2.5 -- could cause "serious health problems," according to an air quality alert issued by the South Coast Air Quality Management District (AQMD) and published by the National Weather Service (NWS).
The AQMD's air quality alert is in place until early Tuesday morning local time and covers California's Coachella Valley -- including the San Gorgonio Pass near Banning and the cities of Indio, Palm Springs, Cathedral City, Palm Desert, La Quinta, and Coachella.
The air quality alert has been issued because there are "harmful levels of particle pollution from windblown dust," according to the statement published by the NWS.
This dust could come from a number of sources, including:
The NWS statement says the PM2.5 levels in the area are likely to vary depending on weather, emissions, time, and location.
Elevated levels of PM2.5 are expected to affect everyone, but those in sensitive groups -- including the elderly, children, and those with existing heart or lung conditions, like asthma -- are likely to be particularly affected.
The Environmental Protection Agency (EPA) says that when PM2.5 reaches "unhealthy" or "unhealthy for sensitive groups" levels, symptoms can range from nose, throat, and eye irritation and coughing, to shortness of breath and chest tightness. Those with existing medical problems may find that their condition is worsened if they're exposed to the polluted air.
Both the EPA and South Coast AQMD say that to reduce exposure to PM2.5, members of the public should try to reduce the duration and intensity of outdoor activities. Those in sensitive groups should try to avoid all outdoor activities, especially when the air quality is deemed "unhealthy" and "unhealthy for sensitive groups."
Alongside reducing exposure to outdoor air, residents are advised to take steps to make sure the air is as clean as possible inside, including in their homes.
They should keep their windows and doors closed, use air filters or purifiers, and avoid using house fans and sources that could create pollution, including candles, wood-burning stoves, and incense, the agencies advise.
PM2.5 is considered by the EPA to be one of the most dangerous forms of air pollution because the polluting particles are so small -- 2.5 micrometers or less in size, or smaller than the width of a strand of hair) -- they can be unknowingly inhaled, penetrating deep into the lungs and even the bloodstream in some cases, triggering or exacerbating health conditions and symptoms.