Legal pot?  All the traffic?  A record number of people eating at Chipotle Grill?  Whatever it is, it's been getting worse:  The Brown Cloud.

The truth is, the air pollution in Denver on Monday was worse than in Beijing, China, which is consistently ranked in the top 10 cities in the world for unhealthy breathing conditions.  The Air Quality Index, which measures the number of pollutants in the air, measured the U.S. Embassy in Beijing at 29, and 174 at a Colorado Department of Public Health and Environment air quality reporting site in downtown Denver.

Brad Dempsey via Twitter

What causes the brown cloud?  Fine particulate matter like dust and nitrous oxide; but, considering all the busy human activity in Colorado, the air here is actually cleaner than most heavily populated areas.  The cloud happens next to the mountains because a layer of warm air gets stuck over a layer of cold air, so any pollution gets stuck overhead.

9 News found several challenges to Brad Dempsey's finding above, as well; but we're glad that Dempsey brought this up, to educate us all!

As much as I love '60s & '70s vehicles, we can be super thankful the vast majority of cars on the road are newer and have loads of emissions restriction equipment.  I've heard that, in the '70s, in Denver, you could barely see across the street.

Society has certainly made strides in respecting Mother Earth and our health.  The Coloradoan did a "look back" to roughly 40 years ago, when the Poudre River was literally a garbage dump.  I'm so glad we wouldn't consider allowing that today; but, I do hope everyone does at least something to personally care for our environment.  At my house, I limit contributing to the landfill almost completely - and it's actually super fun, especially the composting part!