Smoke from a wildfire that has been raging in the nearby Primavera Forest for more than four days is currently shrouding the metropolitan area and provoking health issues for some residents.
Pollution readings higher than 150 Imecas (Mexico's standard for urban air quality measurements) have been noted at several of the city's eight monitoring stations, but since they were not sustained for more than two continuous hours, no alert was issued, Jalisco Environment Agency (Semades) staff clarified Wednesday.
In a Phase One alert, residents of the metropolitan area are advised not to use their vehicles unless absolutely necessary, stay indoors and keep their windows closed.
At 2 p.m. Wednesday, three of the eight stations reported "bad" quality air: Oblatos (117 Imecas), Loma Dorada (107 Imecas) and Atemajac (101 puntos Imecas). The rest reported "regular" pollution levels, or between 50 and 100 Imecas.
Semades officials says they expect to issue a smog alert if the prevailing winds remain the same over the next few hours. While firefighters are managing to control the Primavera Forest fire, the National Forestry Commission says it could be another two or three days before it is extinguished completely.
The Imeca value is determined by calculating levels of gaseous contaminants like ozone, carbon monoxide, sulfur dioxide and nitrogen dioxide per cubic meter measured alongside the total micrograms of suspended particles with diameters less than 10 and 2.5 micrometers.
Any reading higher than 100 is considered hazardous to human health.