I did not see the 17.5 degrees.
The testing for air quality and temperature should be done yearly as well as filters changed regularly depending on the office size. You often find one person gets sick the hole floor gets sick. Filters are very rarely changed in buildings. It does depend on the company as I know one that changes them every 3months. (Scientific company so air quality would be important)
There is no explicit requirement for air quality testing in the legislation though, I'm not sure there are many companies who would even carry out such an audit in general office space operating here.