Each day of every year, a quiet disaster unfolds in households and hospitals across the world. More than 10,000 lives are lost worldwide every 24 hours as a direct or indirect consequence of poor air quality. Bad air takes its toll quietly, with no need for the oversized drama of a hurricane or tornado. Sometimes air quality becomes so dangerous that it can’t be ignored. Much of the time, though, dangerous air goes about its dirty work with little attention from policymakers and the public.
The World Health Organization (WHO) has dubbed air pollution
“the world’s largest single environmental health risk.” It is high time we treated the life-threatening aspects of dirty air, and the life-sustaining properties of a clean atmosphere, with the full appreciation they ought to have. Figure 1.
Los Angeles, CA, shrouded in late-afternoon smog as viewed from the Hollywood Hills. Griffith Observatory is at far left. Image credit: Diliff/Wikimedia Commons
Here at Weather Underground, we are taking steps in this direction by bringing air quality sensors into our 250,000-strong network of personal weather stations
. We believe there is great power in being able to measure the quality of the air in one’s own neighborhood and to share that information with the world at large.
We are also ramping up our coverage of air pollution issues here at Category 6. Along with occasional guest authors, Jeff Masters and I will be exploring the many facets of air quality, including its effects on people and ecosystems and how it intersects with both weather and climate. For example, Jeff will soon be posting an overview of the health hazards posed by poor air quality. This topic was highlighted on March 6 by a distressing report from the World Health Organization
: Each year, respiratory infections linked to indoor and outdoor air pollution and second-hand smoke take the lives of some 570,000 children under the age of 5. That’s roughly 10% of all deaths in that age group each year.Figure 2.
Schoolchildren in Delhi, India, wore masks as schools re-opened on November 10, 2016, after three days of closure due to severe smog. Image credit: Sajjad Hussain/AFP/Getty Images.
For both children and adults, the air indoors can be just as dangerous as the air outdoors. Each year more than 4 million people
die prematurely as a consequence of household air pollution—largely the result of inefficient, smoke-belching cookstoves that are used routinely in developing nations. This toll is even higher than the WHO’s estimate of 3 million premature deaths a year
from outdoor air pollution.
Even the most pristine places can be touched by the global spread of air pollution. In Antarctica, scientists have found traces of lead trapped within ice cores. Using isotopes (variations in the number of neutrons within an element), researchers were able to track the heavy-metal pollution to industrial activity in Australia as far back as the late 1800s
Today, as much as 25%
of the sulfate and mercury pollution along the U.S. West Coast comes from emissions from coal-fired power plants in China. These pollutants take just five to eight days to cross the Pacific on the prevailing upper-level westerly winds.Figure 3.
Motorcyclists ride through thick smog on January 9, 2017, in Zhengzhou, China. The nation’s Central Meteorological Observatory issued a yellow alert for smog in Zhengzhou on Sunday night, January 8. Visibility dropped below 50 meters (160 feet) in parts of the city on Monday morning. Image credit: VCG/VCG via Getty Images.What do we mean by clean air and dirty air?
Some pollutants are invisible and odorless, but you don’t always need highly precise instruments to tell you when the air is at its most polluted. Often you’ll see it, smell it, and even feel it in your lungs.
Observations do tell us a great deal about how air quality varies over time and across regions. The U.S. Environmental Protection Agency tracks six substances known as criteria air pollutants
, meaning that the EPA has established criteria (National Ambient Air Quality Standards
) for the safe and unsafe levels of these airborne substances. The six criteria air pollutants are:• Ground-level ozone
• Carbon monoxide
• Sulfur dioxide
• Particulate matter
• Nitrogen dioxide
All of these are proven health hazards. In many cases, the U.S. has made real progress in reducing their impact. For example, the amount of airborne lead in the United States and other nations has dropped drastically since the 1970s with the advent of unleaded gasoline. This may even be a key factor in reduced crime rates
since the 1990s.
The two biggest airborne health concerns these days are ground-level ozone
and particulate matter
—especially the tiny particles known as PM2.5
(those that are less than 2.5 microns or 0.0001 inch in diameter).
Ozone is a boon to health when it’s in the stratosphere, because it shields us from harmful ultraviolet solar radiation. The problem is when certain fossil-fuel emissions react in the presence of sunlight to form ozone where we live. High levels of atmospheric ozone can cause our respiratory muscles to contract
, irritating our body’s airways and aggravating conditions such as asthma and chronic bronchitis.
Particulates are even more insidious. Along with compromising the respiratory system, the tiniest particles (PM2.5) can also work their way into the bloodstream
. This can elevate one’s risk for heart attacks and lead to a higher mortality risk among people with preexisting heart or lung problems. Figure 4.
Diagram showing the relative sizes of particulates compared with beach sand and human hair. Particles less than 2.5 microns (0.0001 inch) in diameter are the most dangerous. Image credit: U.S. Environmental Protection Agency.New ways to track air quality through WU
Tracking the ups and downs of weather in your own neighborhood—through your own personal weather station or your neighbor’s PWS—has been a core part of WU since our earliest years. We’ve now embarked on a concerted effort to examine the growing options for consumer-level AQ measurement. One of our first goals is to find out which platforms offer the best mix of affordability and quality. As this process evolves, we’ll be sharing what we find so that our community can help build a new network of personal air quality stations.
We are also adding key air quality indexes to many of our “dashboard” pages, which summarize the data gathered at each personal weather station in our network. For example, we’ve recently added AQ data for around 1500 stations across North America that are part of the U.S. Environmental Protection Agency’s AirNow network
. For each of these sites, the weather history graph now includes hourly levels of various criteria pollutants, depending on location (see example below).
AirNow stations are located in both large cities and more rural areas, including Minneapolis, MN
; Provo, UT
; and Washington, DC
. AirNow stations vary in the types of meteorological and AQ data monitored.Figure 5
. Hourly measurements of PM10 (top, in micrograms per cubic meter) and ozone (bottom, in parts per billion) at station KCASACRA81
in downtown Sacramento, CA, on Friday, March 17, 2017.
When it comes to AQ forecasts, you can find an array of local health-related data and forecasts at the “Health” tab when you specify a city or town on WU’s desktop or mobile platforms (see example at bottom).Watch this space
Between major cuts
proposed to the U.S. Environmental Protection Agency and limited public access
to air pollution data in other countries, it is more clear than ever that we cannot take air quality information for granted. WU intends to do its part by expanding our international network of personal weather stations into the realm of air quality.
We'd greatly appreciate knowing what features you'd like as we develop tools for accessing, mapping, and displaying AQ data for both desktop and mobile platforms. Please leave any suggestions as a comment on this post and our developers will collect your input. Watch for more news on this initiative later in the spring.
Bob HensonFigure 6.
A variety of health-related features can be accessed when you select “Health” beneath a city name on WU’s city pages. This health dashboard for Atlanta, GA, on Tuesday afternoon, March 21, 2017, showed that air quality was rated “moderate” for PM2.5 and was predicted to remain moderate on Wednesday. Pollen counts were running high for pine, oak, and birch trees.