BEIJING — Earlier this month, a U.S. study on the economic impact of China’s air pollution was released with little fanfare. Maybe it was because of the series of successive “blue sky” days we were enjoying in the Chinese capital, thanks to the gusty winds blowing down from Mongolia. 

The study, which was conducted by researchers at the MIT Joint Program on the Science and Policy of Global Change, breaks down costs that result from the health impacts from ozone and particulate matter, which typically lead to respiratory and cardiovascular diseases.

---

The conclusion? “[D]espite improvements in overall air quality,” the cost of air pollution (as in lost economic productivity growth) in China has mushroomed from $22 billion in 1975 to $112 billion in 1995. But for at least one pair of 29-year old software engineers in Beijing, air pollution has actually meant greater economic productivity and a business opportunity.

A killer app
Wang Jun and Zhang Bin each moved to Beijing in 2001 to attend college.  Zhang, a Fujian native, was a math major at Beijing University while Wang left Inner Mongolia to study traffic infrastructure at Jiaotong University.

They met at a high-tech company, where for three years they worked together. Last year, they decided to strike out on their own and set up Fresh Ideas Studio.

“The primary aim … is creating mobile apps for solving practical problems in our daily lives,” Wang said, on a blustery (but sunny) afternoon at a coffee shop.

Last year saw some of the worst air pollution in Beijing since the 2008 Summer Olympics, spurring intense discussion among Chinese residents, teeth-gnashing among Western expats, and a near-diplomatic spat between the U.S. and China over fine particulate matter in the air known as PM2.5 that can wreak havoc on the respiratory system.

“Recently, the media and Weibo [a popular Chinese microblog like Twitter] users are very concerned about air quality, especially in Beijing,” Wang said.

In particular, there was a lot of online chatter about @Beijing Air, the U.S. embassy Twitter account that posts hourly Air Quality Index(AQI) data. 

The readings come from an air quality monitor that sits on top of the embassy in downtown Beijing, and they differ sharply from the daily results posted by the Ministry of Environmental Protection (MEP).

AQI values on @BeijingAir range from 0 to 500.  A “good” AQI  is 0 to 50 or what the Chinese call a “blue sky” day.  Unfortunately, many days in 2011 qualified as “unhealthy” to “hazardous.”  But on some of those same days, MEP data maintained the levels were “good” or “moderate.”  (The Chinese, in fact, claim there were 286 "blue sky" days in 2011.)

“The [Beijing] government says that nearly 80 percent of the days in the last two years met at least the Chinese standard and therefore had good or even excellent air quality,” Steve Andrews, an environmental consultant who has analyzed the @BeijingAir data, said. “While when we look at the U.S. Embassy data … over 80 percent days exceeded what would be considered healthy air quality and more days were hazardous than good.”

Andrews said that Beijing's pollution levels were "six or seven times higher than the U.S.'s most polluted city." "Air pollution at these levels likely shortens life expectancy by about five years," he added.

The discrepancy was due to the fact the U.S. embassy monitor includes PM2.5, a fine particulate matter measuring 2.5 micrometers in diameter that, according to the EPA, “pose the greatest health risks [and] can lodge deeply into the lungs.”

The Chinese data, however, only measured the much coarser PM10 particles.

“I’m a Twitter user and saw many Tweets about [@BeijingAir],” Zhang said. “Many Weibo users reposted the data, too.”

The software developers decided to try creating a smartphone application that based itself on the @BeijingAir data.

“Sometimes we can tell there’s a gap between what we feel and the data from the government,” Wang said.  “This is probably why many prefer the data provided by the U.S. embassy.”

In November, they released a 1.0 version, available only in Chinese and which came with simple but appealing graphics.  On good AQI days, the screen background was light and featured a hiking boot, indicating it was time to be outdoors. On bad AQI days, the screen background turned dark, an X marked the boot, and a person’s face wrapped in a mask would pop up.

There were iOS and Android versions of the app. Within weeks, it had been downloaded 80,000 times. At least half of those users checked the app regularly, according to Wang. 

Pollution 'ignored' in past
Under popular pressure that has been building since last year, Chinese environment authorities in Beijing have agreed to publish PM2.5 data. But they maintain the air quality has improved steadily in recent years. 

“We may have had bad pollution in the past, but people probably didn’t pay too much attention to it before so it was just ignored,” said An Xinxin, who works in the Automatic Monitoring Office at the Beijing Environmental Protection Monitoring Center. 

The Center relies on anywhere from 30 to 40 monitoring stations. “Almost every district and county in Beijing has its own station,” explained An. “So citizens in every district and county can know what the pollution in their own area is like.”

Like many of his colleagues at the municipal level, An pointed out that the U.S. embassy only uses one monitor. “[It] can only represent one spot at a certain time. Their spot might be very close to the road where there is a lot of vehicle exhaust, which causes a high level of PM2.5,” he said. “Our statistics are an average of Beijing as a whole, not just one spot.”

Zhang has lived in Beijing for more than ten years, but he said he’s not sure whether the air quality has improved or not. “I don’t know if it’s because now I pay more attention [because of the media and online discussion], or if it’s because the air quality has worsened,” he said. 

But he and Wang dreamed up the idea of incorporating both the Chinese and American data streams into their app.

On Monday this week, they introduced a 2.0 version that not only posts real-time data from the U.S. embassy in Beijing and U.S. consulates around China, it also includes data from the Chinese Ministry of Environment’s monitoring centers in 120 cities across the country.

Also available in English, the app has been downloaded nearly 5,000 times.

“We thought it was good to include both. In some cities, users might want alternative information,” Wang said. “If there were a third source for air pollution data, we’d probably include it in the app, too.”

They might also want to add Hong Kong to their list of cities.

This month, a local nongovernmental group said Hong Kong’s air is 20 per cent more deadly than the air in mainland China. 

Using data from Hong Kong’s own government and the World Health Organization, the Clean Air Network ranked Hong Kong ahead of mainland China, India, Vietnam, and Bangladesh for its high air pollution mortality rates.

More from msnbc.com and NBC News:

• Australia's 'dingo baby' mystery finally solved?
• Clinton: Syria rebels will get arms 'somehow'
• NBC's Kabul correspondent discusses Quran outrage
• Actress Lucy Lawless boards ship to protest Arctic oil drilling
• Hacked arms and legs display the despair of Somalia
• Michael Jordan sues for control of his name in China
• Ancient Maya doom teaches climate lesson
• Russians rally for Putin — and 2 days off work
• US pro-democracy worker stopped at Egypt airport

With additional reporting from Bo Gu and Ting Zhao.

MANAMA, Bahrain - As the anniversary of a failed pro-democracy uprising approached in Bahrain, the United States warned Americans in the tiny Gulf kingdom of potential unrest and moved embassy employees to safer locations.

The travel alert issued late on Monday did not specifically mention the anniversary of the uprising on February 14 last year when protesters, mainly from Bahrain's majority Shiite population, took to the streets of Manama to demand political rights.

---

The country is dominated by the ruling Al Khalifa dynasty, a Sunni family closely allied to other Gulf rulers and seen as a bulwark against Shia-dominated Iran's influence in the Arabian peninsula. It is also home to the U.S. 5th Fleet.

The U.S. State Department said the Bahrain government had recently refused entry to some U.S. citizens at Manama airport and that U.S. embassy employees were being relocated within the country because of the potential for violent demonstrations.

• Bahrain fires tear gas, stun grenades to halt protesters

It also noted what it called "isolated examples" of anti-U.S. sentiment such as flag-burnings during protests and warned that foreigners could become targets.

"The Department of State strongly urges U.S. citizens to avoid all demonstrations, as even peaceful ones can quickly become unruly, and a foreigner could become a target of harassment or worse," the alert, which runs to April 19, said.

It warned of spontaneous and sometimes violent anti-government demonstrations by protesters throwing rocks and petrol bombs, lighting trash cans and blocking highways.

"The Ministry of Interior maintains official checkpoints in some areas and routinely uses tear gas, stun grenades, and other crowd control measures against demonstrators," it said.

Washington stood behind Bahrain's government during the protests, while removing its support for rulers in Egypt and Tunisia. However, it has made an arms deal contingent on political reform.

• Bahrain to citizens living abroad: Spy on countrymen, no protests permitted

The protest movement was crushed after a month when Saudi troops entered Bahrain to back the government, followed by nearly two months of martial law.

A rights commission headed by international lawyers said in November that 35 people - including protesters and security personnel - were killed up to June. Activists say deaths among Shiites apparently as a result of the clashes have taken the casualty list to around 60.

Bahraini employees of some companies say they have been told not to take any holidays in the coming months, in an apparent effort to discourage people from taking part in protests.

Reuters, The Associated Press and msnbc.com staff contributed to this report.

More from msnbc.com and NBC News:

BEIJING—While China’s chief climate negotiator is getting rock star treatment at the Durban climate summit this week, his peers back in the capital are suffering a third straight day of foul air.

As a leading Canadian newspaper put it, China provided “the few glimmers of hope at the stalled negotiations” in Durban, where "photographers and television journalists swarmed around the chief Chinese negotiator, Xie Zhenhua, as he entered a news conference on Monday to announce his list of conditions for considering a legally binding treaty on carbon emissions after 2020."

---

It seems that despite being the world's biggest carbon emitter, China could be the key to a deal on a legally binding agreement to reduce emissions.

However, not many glimmers of hope could be spotted back home.

A persistent 'fog'
The Chinese state-run print media all ran headline stories Tuesday morning on the persistent "fog" that has blanketed Beijing and parts of the country’s northeast since the weekend. (See video above of the "hazardous" level of smog on Monday).

Much of the coverage focused on the hundreds of flights cancelled at the Beijing Capital International airport—the world’s second busiest hub—or the rising and very vocal concerns about air pollution.  Some local reports referred to sales of air filter masks and air filter machines spiking in the past week.

Still more reports tried to cast the air pollution issue as one of sovereignty.  "The heavy fog or smog that has shrouded Beijing in the past couple of days has triggered a renewed round of debate over the different air pollution standards applied by China and the United States," said an opinion piece in the Global Times, a state-run newspaper with a strong nationalist overtone.

But at least these same newspapers are now calling it "smog" rather than "fog," as they were just a day ago.  The China Daily, another state-run newspaper, ran a headline on page 3 crying, "Exposure to smog is severe hazard."  Later in the day, the paper’s web site posted four stark images of the same location showing changes in air visibility. (See photo above). The images are pretty staggering.

Only 13 days of 'good' air this year so far

And as we write this, the ever-trusty and ever-reliable @BeijingAir Twitter feed has been down five hours, prompting followers to wonder whether the pollution has finally gotten to the air quality index monitor that lives on top of the U.S. Embassy in Beijing.

A sobering analysis of the @BeijingAir feed can be found in this post by China Dialogue, which notes that the improvements in air quality claimed by officials at the Beijing Environmental Protection Bureau "are due to irregularities in the monitoring and reporting of air quality – and not to less polluted air."

Moreover, based on the analysis using the @BeijingAir data, this year there have only been 13 days of "good" air quality. 

Buried further amidst the quantitative data was one more alarming point: "…if Beijing’s fine particulate concentration even reached the polluted levels of Los Angeles, life expectancy may increase by over five years."

We at NBC News Beijing are trying to claw back a few months to our life span.  We have just taken delivery of two air filter machines for the bureau.