Air pollution is the largest environmental health risk in the UK, responsible for an estimated 40,000 premature deaths per year according to Public Health England. This is not an abstract statistical risk. Particulate matter with an aerodynamic diameter of 2.5 micrometres or less, PM2.5, is of particular concern because these particles are small enough to pass through the alveolar membranes into the bloodstream, and from there into tissues including the heart, brain, and placenta. The health effects of chronic exposure to elevated PM2.5 are well-characterised and span cardiovascular disease, respiratory conditions, neurological disease, and adverse pregnancy outcomes.
Cardiovascular and Neurological Effects
The Global Burden of Disease study estimates that air pollution is responsible for more cardiovascular deaths than dietary salt or alcohol. The mechanisms include endothelial inflammation, platelet activation, and arterial stiffness driven by PM2.5 and gaseous pollutants including nitrogen dioxide and ozone. The neurological effects are increasingly recognised: multiple large cohort studies have found associations between long-term exposure to elevated PM2.5 and increased rates of dementia, accelerated cognitive decline, and structural brain changes including reduced grey matter volume in regions associated with cognition and emotion.
Indoor Air Quality
Indoor air quality is often assumed to be better than outdoor, but UK and WHO data consistently show that indoor pollutant concentrations frequently exceed outdoor levels. Sources include cooking combustion from gas hobs, which produce nitrogen dioxide and fine particles; cleaning products and air fresheners that emit volatile organic compounds; new furniture, carpets, and building materials that off-gas formaldehyde and phthalates; and inadequate ventilation that allows CO2 and pollutant accumulation. The time spent indoors, approximately 90 percent for UK adults, makes indoor air quality the primary chronic air quality exposure.
Practical Indoor Air Quality Improvement
HEPA-filter air purifiers have strong evidence for reducing indoor PM2.5 concentrations by 50 to 80 percent in the rooms in which they operate. Ventilation, even brief window opening for 10 to 15 minutes per hour, significantly reduces indoor pollutant concentrations. Cooking with extraction ventilation reduces combustion particle exposure substantially. Houseplants contribute modestly to indoor air quality and have marginal evidence for VOC reduction, but not at concentrations sufficient to replace ventilation or filtration.
- Use a HEPA-filter air purifier in the bedroom and main living space: it is the highest-impact indoor air quality intervention
- Install and use extractor ventilation when cooking, particularly on gas hobs
- Ventilate rooms regularly: 10 to 15 minutes of window opening per hour reduces CO2 and VOC accumulation
- Avoid synthetic fragrance products indoors: air fresheners, scented candles, and cleaning products are significant VOC sources
- Check local authority air quality monitoring data for your area and avoid outdoor exercise during high pollution episodes
Sources
- Public Health England. (2019). Review of interventions to improve outdoor air quality and public health. PHE publications.
- Landrigan, P.J., et al. (2018). The Lancet Commission on pollution and health. Lancet, 391(10119), 462-512.