Emissions Estimation

Indoor air quality in urban commercial buildings - Do we require legislative limits to protect health?

Research shows people now spend up to 90% of their day indoors yet in Ireland no legislative indoor air pollutant limits exist. Legislative reductions in air pollutant limit values seek to improve outdoor air quality, in turn reducing associated illnesses such as asthma, acute bronchitis, strokes and lung cancer. Our research focuses on two air pollutants, NOx (NO2 + NO) and PM2.5 (particulate matter with aerodynamic diameter less than 2.5µm, two pollutants that air quality legislation considered of most concern. Our research aims to improve our understanding of the relationship between exposure of staff to specific air pollutants in Irish working environments (e.g. shops, offices) and outdoor air pollutants, investigating controlling factors such as ventilation systems and door design for such buildings.

NOx and PM2.5 concentrations are measured simultaneously indoors and outdoors of buildings. Outdoor concentrations are measured in two locations either directly outside the building at ground level or at the air intake of the buildings ventilation system. To date ten work places located on busy street canyons within Dublin city centre have been monitored.

Results indicate that indoor concentrations can be significantly greater than outdoor concentrations for certain sites, e.g. Indoor Outdoor ratios (I/O) of up to 2.0 for NO2 and 2.1 for PM2.5. Other sites however, have shown significant reductions in pollutant concentrations indoors compared to outdoors, with I/O ratios as low as 0.32 for NO2 and 0.45 for PM2.5. Clear differences in lag times and I/O ratios for PM2.5 and NOwere also observed for working and non-working hours. The building with the greatest reduction for NO2 was a naturally ventilated office while the greatest PM2.5 reduction was seen in the mechanically ventilated office.

A graph displaying indoor and outdoor concentration of NO2 for a naturally ventilated office

Project coordinator: Prof. Laurence Gill

Monitoring ambient hydrocarbons

Motor vehicles emit a variety of atmospheric pollutants. Amongst these are a variety of hydrocarbons, including benzene, the ambient concentrations of which are to be limited by recent EU directives. Our research involves the on-line measurement of ambient hydrocarbon concentrations in the vicinity of a motorway and at a busy junction in Dublin city centre. At these locations, concentrations of many hydrocarbons can, in the main, be attributed to road-traffic emissions.

Further to this, adapting the on-line system to accommodate a more flexible, portable and mobile sampling method based on the use of tedlar bags as sampling vessels is considered. This method facilitates a wide range of sampling applications, such as the measurement of background concentrations, emission factors and the spatial distribution of pollution levels.

Lastly, applying this “mobile sampling” method in Ireland allows for the spatial mapping of Dublin city along with “real world” driving emissions, a topic that is requires a potential focus in future research.

A photo of fumes from diesel

Project coordinator: Prof. Brian Broderick