There are many manufacturers for profesional Air Qualtiy monitoring station. Below is a non-exhaustive list of few of them, together with their most famous products.

Note that Air Quality monitoring equipment manufacturers (expect from ES Labs) are famous for their lack of transparency on pricing. One can expect arround $10K per station, and that's just bare price excluding installation and maintenance. If you are asked to pay more than that, then you should ask for the quotation from other vendors.
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If you would like to suggest a product on this listing, you can go to the registration page. Registration is free, but please note that we are very strict about quality and certification, so if your product is not certified, we will most likely not be able to accept it.

There are so many air quality related products on the market; Some are good, other are bad. For consumers like us, it can sometime be difficult to find out which product is good and worth buying and which one is bad and should not be bought. For this reason, we have created this 'Air Quality Products' page on which you will find a selection of products that we have carefully studied and evaluated.

Protection Masks & Respirators

Home Air Purifiers

Personal Air Quality Monitors

DIY Air Sensors

Professional Air Quality Monitoring Stations

Professional Air Cleaners

About the Air Quality Levels

AQI	Air Pollution Level	Health Implications	Cautionary Statement (for PM2.5)
0 - 50	Good	Air quality is considered satisfactory, and air pollution poses little or no risk	None
51 -100	Moderate	Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution.	Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion.
101-150	Unhealthy for Sensitive Groups	Members of sensitive groups may experience health effects. The general public is not likely to be affected.	Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion.
151-200	Unhealthy	Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects	Active children and adults, and people with respiratory disease, such as asthma, should avoid prolonged outdoor exertion; everyone else, especially children, should limit prolonged outdoor exertion
201-300	Very Unhealthy	Health warnings of emergency conditions. The entire population is more likely to be affected.	Active children and adults, and people with respiratory disease, such as asthma, should avoid all outdoor exertion; everyone else, especially children, should limit outdoor exertion.
300+	Hazardous	Health alert: everyone may experience more serious health effects	Everyone should avoid all outdoor exertion

To know more about Air Quality and Pollution, check the wikipedia Air Quality topic or the airnow guide to Air Quality and Your Health.

For very useful health advices of Beijing Doctor Richard Saint Cyr MD, check www.myhealthbeijing.com blog.