The primary purpose of the MAMUs is to collect continuous PM10 data to provide information on the air quality at the location where the equipment is located. Each unit is housed in a single axle trailer (5 foot by 8 foot) that provides both security and allows the air monitoring station to be moved and deployed easily. Inside each trailer, a Met One E-Sampler collects continuous particulate matter data via a mounted inlet extending through the roof of the trailer. Along with continuous PM10 data the E-Samplers are equipped to collect a filter sample for mass-based lab analysis or particulate characterization. Each MAMU also has a dust fall canister mounted to the trailer to collect monthly dust fall samples.
The MAMU trailers are equipped with a pole mount Met One anemometer to measure wind speed and direction. A temperature sensor and relative humidity (RH) sensor are mounted to the outside of the trailers. All components mounted outside the trailer can be easily detached when the MAMUs are moved. Data from the MAMU trailers is transmitted electronically to WSP Canada Inc. for analysis and inclusion on Westshore's Air Quality Monitoring Website.
Dust fall is the term used to describe air particles that settle down over a given area and time under the influence of gravity. Measuring dust fall can determine if a particle source is causing unacceptable dust nuisance in surrounding areas.
Dust fall is measured with a dust fall deposit gauge, typically mounted on an elevated stand to avoid surface dust interference. This simple piece of monitoring equipment comprises a glass bottle containing a small amount of water.
It is usually necessary to sample dust fall over 1 month to ensure a measurable quantity of dust is captured in the gauge and can be sent to a laboratory for analysis. The dust fall rate is calculated by dividing the weight of insoluble material collected (in milligrams) by the cross-sectional area of the bottle (square metres) and the number of days over which the sample was taken. The units of measurement are milligrams per square metre per day. Dust fall is not affected by the colour of the dust but darker dust is usually perceived by the public as having more impact than light-coloured dust.
Metro Vancouver provides a range for their Ambient Air Quality Objectives for dust falls: 1.7 mg/dm2/day - 2.9 mg/dm2/day.