This week, air pollution in China became a national concern as heavy smog in Beijing grounded hundreds of flights due to visibility issues. The U.S. Embassy in China now routinely takes samples and studies of the air quality for study, and the information is available through their Twitter feed. Their readings during the worst of this smog crisis were literally so high that the chart the American EPA uses to classify pollution-related health risks didn't have a rating high enough.
In the meantime, Chinese government readings were significantly lower due to the fact that they have created a different scale that ignores many of the pollution-causing particles and only measures certain pollutants. This allows their readings to be significantly lower.
While the average Chinese citizen has no access to Twitter, the embassy's readings have been reposted in so many places that the news was received by the public and has been the cause of a rising online protest.
If nothing else, this event shows that all forms of pollutants are dangerous, regardless of context. If you want to protect your family, whether traveling overseas or just in your own home, invest in a medical-grade air purifier and keep the air in your home fresh, clean and healthy.