Something need to know before use particle counter

First of all, we need to know more the harm of PM2.5?
Each year about 2.1 million people died of PM2.5 particles concentration increased
It is understood that in 2012 the United Nations environment programme (unep),
the global environment outlook 5 points out that there are 700000 people die each year
from respiratory disease caused by ozone, nearly 2 million premature deaths associated with particulate matter pollution.
The proceedings of the national academy of sciences (PNAS) also published research report,
said in a report, human life expectancy because air pollution is likely to have shortened the five and a half years.
before you order particle counter need to know above this information.