There are no regulations on air quality in tunnels, therefore Swedish Transport Administration is developing a measuring and quality system for the Stockholm bypass. They will set their own limits, and have promised that they will be able to uphold the levels they set.
The Stockholm bypass has no air purification system. The air exchange is created by the backdraft from the cars themselves and fanned ventilation towers pulling air out and pushing fresh air in.
During the operational and maintenance phase of the Stockholm bypass an earlier conducted study showed that energy use will be about 180 000 GJ (50 GWh) per year. Most of the energy would be used for tunnel ventilation, about 86% of the total energy usage. The calculations for managing air quality in the tunnels and for local residents around the tunnel buildings were based on a lower active time for the fan system. Unfortunately energy consumption will be even higher since the Swedish Transport Administration now estimates the need to run the ventilation system 18 hours per day (24 hours per day during the winter months).
Air pollution in the tunnels is expected to be 50-100 times higher than allowed levels out in the open, and in rush hour up to 18 times worse then the worst days in Beijing. The quality of tunnel air will pose a risk to anyone who travel through the tunnels.
A person commuting 5 days per week through the tunnel system will have a 10% increased risk of dying prematurely. The risk will be even higher if the journey takes more than 15 minutes. The speed limit in the main tunnels will be set at 90 km/h. To travel the full distance takes 15 minutes.
Those most at risk are people with pulmonary and cardiovascular diseases, asthma and allergies, old people, children and pregnant women. All in all 40% of the population will be advised to take another route or travel in the tunnels at their own risk.
Due to the poor air quality traffic jams cannot and will not be allowed in the Stockholm bypass tunnels. Swedish Transport Administration will solve this by installing traffic lights at the tunnel entrances to stop vehicles from entering. The traffic jams in Stockholm will relocate and instead spread out on the roads connected to the tunnels.