Dyson air sensing technology reveals the impact of Bangkok's seasonal haze on personal pollution exposure

Re-working existing sensing technology used in Dyson air purifiers, Dyson’s air quality backpack is a portable air sensing device that collects air pollution data on the move. With on-board sensors, a battery pack and GPS, Dyson hopes to use this sophisticated technology to offer insights into personal exposure to air pollution and how to avoid it.

Dyson engineers analysed the findings by pairing the air sensor and GPS data from the backpack with Pongsuk’s diary entries, where he documented his activities and observations in the period wearing the air quality backpack. This allowed them to understand what may have caused the pollution and how Pongsuk might be able to lower his exposure in the future.

PM2.5 levels were over nine times worse during haze season

Compared to Phase 1, the pollution data collected in the Phase 2 haze period indicated a significant increase in Pongsuk’s personal exposure to PM2.5 levels, with average levels rising by up to nine times⁴. Bangkok frequently experiences higher particulate matter (PM) pollution levels in cooler winter months, potentially caused by several factors including vehicle pollution, weather, electricity generation, industrial emissions, and seasonal agricultural fires⁵.

During this time, data collected from Pongsuk stepping out of the car before entering an office building caused PM2.5 levels to increase by up to 3.8 times⁶. This was likely caused by exposure to the city-wide pollution event while travelling outdoors.

Pollution spikes from daily activities

As well as this overarching seasonal pollution change, the air quality data indicated that daily activities further contributed to pollution spikes.

Travelling by motorbike caused NO₂ levels to increase to up to 200 µg/m³, which was up to 50 times higher than before, registering as ‘extremely poor’ on Dyson’s air quality index. Engine combustion from vehicles can release NO₂ pollution, likely contributing to this increase during that period.

Moreover, while Pongsuk was driving his car, his exposure to PM2.5 and Volatile Organic Compounds (VOCs) increased. PM2.5 can be emitted by brake and tyre wear, which individuals can be exposed to even if they are within the vehicle cabin.

Indoor air pollution

While air pollution is often associated with the outdoors, sources of pollution are also present within the home. During Pongsuk’s data collection, PM2.5 was identified while he was at home with his family. This could have been emitted during cooking activities, as combustion releases particulate matter into the air. The disturbance of dust caused by human movement or an open window letting in outdoor pollutants, may have also contributed to this increase.

On one night when Pongsuk was sleeping, indoor pollution levels remained constant at 30 µg/m³ and did not drop. Over this 10-hour period, PM2.5 levels were up to two times higher⁷ than prescribed WHO safe levels⁸. As well-sealed homes can lead to pollutants being trapped indoors and lingering overnight, it is recommended to ventilate the home when the outdoor air quality is good. When outdoor air pollution is high, keeping windows and doors closed while operating an air purifier at home is advised.

Dyson purifier data also revealed up to two times higher⁹ PM2.5 levels indoors during the haze period against the non-haze period. This rise in the overall particulate matter exposure measured in Bangkok homes corresponds with the air quality data recorded using Dyson’s prototype air quality backpack, indicating a shift in the air quality index from ‘good’ in Phase 1 to ‘fair’ in Phase 2.