david tellez was out for his daily jog hearing about pm 2.5 for the first time. pm 2.5 is there like another term for it particulate matter 2.5 is 2.5 micrometer particles. these are very, very tiny particles. the problem with a particle that is that small, you can fit 40 of them across the human hair, that they not only embed in the lung and cause irritation of the lung and trigger breathing problems in patients with asthma, patients with emphysema, copd and young children with lungs that are still forming. but they can actually be in, inhaled and absorbed into the bloodstream doctor daly says kaiser's emergency department sees an increase in heart attacks and strokes on poor air quality days he urges everyone to get an n95 mask, which protects against 95% of particulate matter it's an important thing to realize that's not 100%. this is not designed for somebody to say, oh, the air quality is poor. i'm going to go put on my n95 mask and go jogging today, right? you're still exposing yourself to 5% of these, particulate matter. doctor daly also says a regular mas