The abundance of volatile organic compounds (VOCs) found in homes depends on many factors such as emissions, ventilation and the oxidative environment and these are evolving over time, reflecting changes in chemical use, behaviour and building design/materials. The concentrations of VOCs in 25 UK homes of varying ages, design and occupancy were quantified using continuous indoor air sampling over five days. Air was collected through low flow (1 mL min) constant flow restrictors into evacuated 6 L internally silica-treated canisters until the canisters reached atmospheric pressure. This was followed by thermal desorption-gas chromatography and high mass accuracy time-of-flight mass spectrometry (TD-GC-TOF/MS). A fully quantitative analysis was performed on the eight most abundant hydrocarbon-based VOCs found. Despite differences in building characteristics and occupant numbers 94% of the homes had d-limonene or α-pinene as the most abundant VOCs. The variability seen across the 25 homes in concentrations of monoterpenes indoors was considerably greater than that of species such as isoprene, benzene, toluene and xylenes. The variance in VOCs indoors appeared to be strongly influenced by occupant activities such as cleaning with 5-day average concentrations of d-limonene ranging from 18 μg m to over 1400 μg m, a peak domestic value that is possibly the highest yet reported in the literature.
Dementia is an umbrella term for a range of conditions that affect how the brain works and, in particular, the ability to remember, think and reason. It mainly affects older people, both men and women, and gets worse over time. In recent years, there has been growing interest in the possibility that exposure to outdoor air pollution could increase the risk of dementia. COMEAP reviewed epidemiological and experimental studies and concluded that it is likely that air pollution contributes to a decline in mental ability and dementia in older people. The most likely way this occurs is through effects on the circulatory system. It is known that air pollutants, particularly fine particles, can affect the heart and blood vessels, including those of the brain. These effects are linked to vascular dementia, which is caused by damage to the blood vessels in the brain. Experimental studies suggest that air pollution may also stimulate immune cells in the brain, which can then damage nerve cells. It is also likely that some nano-sized (ultrafine) particles can enter the brain, either by transport along the olfactory nerve or by entering the circulation and crossing the blood-brain barrier. These particles may cause direct damage. Nonetheless, based on the available evidence, it does not seem likely that this is an important mechanism for the development of dementia. Recommendations were made for further research which would help develop the evidence on this important topic.
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