Authorities in Mexico City declared an environmental emergency Tuesday as smoke from wildfires caused air pollution to reach levels well above what the World Health Organization (WHO) considers safe.

The Nezahualcoyotl measuring station recorded particulate matter (PM2.5) levels of 158 micrograms per cubic meter of air at 5 a.m. Tuesday morning, Reuters reported. That's more than six times the WHO recommended level of below 25. While the emergency was declared Tuesday, the air had been thick with smoke since Saturday, NBC News reported. "You can't escape it," a tour bus operator told Bloomberg News.

In light of alarmingly bad air quality, Mexico City officials issue warning: BREATHING IS BAD FOR YOUR HEALTH. pic.twitter.com/ezIk7V4exf — Laura Martínez (@miblogestublog) May 13, 2019

Government agency the Megalópolis Environmental Commission (CAME) advised residents to stay inside, place wet towels under their doors and avoid activities that could make air quality worse, like cooking with wood or coal, smoking and lighting candles, NBC News reported. The local government also said it would restrict vehicle traffic Wednesday, according to Reuters. Mexico City Mayor Claudia Sheinbaum said she was considering closing schools, and a local soccer league, Liga MX, decided to delay its semifinals. Mexico City's once famously dangerous air quality has improved in recent decades, partly through a policy of restricting traffic on days when pollution reaches elevated levels, Bloomberg reported. But the current pollution comes mostly from wildfires outside the city, not exhaust.

Terrible air pollution generating apocalyptical vibes in Mexico City this weekend. All over the city the air tastes and smells of smoke. pic.twitter.com/fm2buZ9Ca3 — Duncan Tucker (@DuncanTucker) May 12, 2019

There were 23 fires burning on Sunday, Mexico City's Fire Department said, as NBC News reported. The fires have prompted authorities to declare emergencies in 11 municipalities in the southern state of Oaxaca. Blazes have also been reported in Valle de Bravo, Tepoztlán and Jalisco. The fires around the city have been fueled partly by hot, dry weather. Mexico City temperatures have been above average on 73 days this year. "The climate works against Mexico City and the area has a baseline of poor air quality from urban sources," Air Quality Program director and NYU Marron Institute of Urban Management associate professor Kevin Cromar told NBC News. Rising temperatures in Mexico have been linked to climate change, according to the Climate Reality Project: In fact, by the end of this century, northern Mexico could see its average annual temperatures rise by 3 – 4 degrees Celsius (about 5.4 – 7.2 Fahrenheit). And the rest of the country? It could see temperatures climb by 1.5 – 2.5 degrees Celsius (about 2.7 – 4.5 Fahrenheit).



A few degrees might not seem like a big deal, but think of it this way: What's the difference between 0 and 1 degree Celsius? Well, that's the difference between ice and water. A small change in temperature can really disrupt the systems we depend on to survive.



As Mexico (and our world) becomes warmer, the fingerprints of climate change can be seen everywhere you look. Climate scientists observe impacts like sea-level rise, longer and more intense wildfire seasons, and devastating droughts (just to name a few). And more importantly, everyday people experience the effects. Air pollution has been associated with a growing list of negative health impacts, from Air pollution has been associated with a growing list of negative health impacts, from lung and heart disease to dementia . It is responsible for an estimated 4.2 million early deaths each year, according to WHO