Not at all, the mechanical system will ensure 30m3 of filtered fresh air is continually provided every hour, for every person in the building, and in the very unlikely event the system stops working for a time, you can rely on opening windows and doors just like a typical building.
It is probably truer to say it is unhealthy to be in a leaky draughty building where the temperature fluctuates and the lack of air-tightness results in uncontrolled air flows both in and out of the building which can leave parts of the building under supplied with quality tempered fresh air, creates an increased mould risk, and lets pollutants and dust in.