Indoor Exposure to Selected Air Pollutants in the Home Environment: A Systematic Review

Abstract

(1) Background: There is increasing awareness that the quality of the indoor environment affects our health and well-being. Indoor air quality (IAQ) in particular has an impact on multiple health outcomes, including respiratory and cardiovascular illness, allergic symptoms, cancers, and premature mortality. (2) Methods: We carried out a global systematic literature review on indoor exposure to selected air pollutants associated with adverse health effects, and related household characteristics, seasonal influences and occupancy patterns. We screened records from six bibliographic databases: ABI/INFORM, Environment Abstracts, Pollution Abstracts, PubMed, ProQuest Biological and Health Professional, and Scopus. (3) Results: Information on indoor exposure levels and determinants, emission sources, and associated health effects was extracted from 141 studies from 29 countries. The most-studied pollutants were particulate matter (PM2.5 and PM10); nitrogen dioxide (NO2); volatile organic compounds (VOCs) including benzene, toluene, xylenes and formaldehyde; and polycyclic aromatic hydrocarbons (PAHs) including naphthalene. Identified indoor PM2.5 sources include smoking, cooking, heating, use of incense, candles, and insecticides, while cleaning, housework, presence of pets and movement of people were the main sources of coarse particles. Outdoor air is a major PM2.5 source in rooms with natural ventilation in roadside households. Major sources of NO2 indoors are unvented gas heaters and cookers. Predictors of indoor NO2 are ventilation, season, and outdoor NO2 levels. VOCs are emitted from a wide range of indoor and outdoor sources, including smoking, solvent use, renovations, and household products. Formaldehyde levels are higher in newer houses and in the presence of new furniture, while PAH levels are higher in smoking households. High indoor particulate matter, NO2 and VOC levels were typically associated with respiratory symptoms, particularly asthma symptoms in children. (4) Conclusions: Household characteristics and occupant activities play a large role in indoor exposure, particularly cigarette smoking for PM2.5, gas appliances for NO2, and household products for VOCs and PAHs. Home location near high-traffic-density roads, redecoration, and small house size contribute to high indoor air pollution. In most studies, air exchange rates are negatively associated with indoor air pollution. These findings can inform interventions aiming to improve IAQ in residential properties in a variety of settings.

Indoor Air Quality at Home—An Economic Analysis

“…The English Housing Survey was used to determine the total number of dwellings in England and to stratify them by tenure [ 11 ]. The average number of inhabitants per dwelling in the United Kingdom [ 2 , 3 ] was then multiplied by the number of dwellings to estimate the total number of inhabitants, across each tenure category, within the baseline population [ 12 ] ( Supplementary Materials Part I ).…”

“…People in Europe spend up to 90% of their lives indoors and 66% of this time is spent at home [ 1 ]. Indoor air quality has an impact on multiple health outcomes, including respiratory and cardiovascular illness, allergic symptoms, cancers and premature mortality [ 2 , 3 ]. Common pollutants include particulate matter (PM 2.5 and PM 10 ); nitrogen dioxide (NO 2 ); and volatile organic compounds (VOCs) including benzene, formaldehyde and polycyclic aromatic hydrocarbons (PAHs).…”

“…Common pollutants include particulate matter (PM 2.5 and PM 10 ); nitrogen dioxide (NO 2 ); and volatile organic compounds (VOCs) including benzene, formaldehyde and polycyclic aromatic hydrocarbons (PAHs). Sources of these pollutants include smoking, cooking, heating, unvented gas heaters and cookers, solvent use, renovations, new furniture, household products and biological sources (e.g., moulds) [ 1 , 3 , 4 ].…”

“…For example, a systematic review of 31 studies showed that exposure to damp was related to increased risk of all types of rhinitis [ 4 ]. High indoor particulate matter, NO 2 and VOC levels were typically associated with respiratory symptoms, particularly asthma symptoms in children [ 3 ]. A systematic review of studies from 123 countries showed that the relative risk (RR) for asthma associated with the use of polluting fuels and technologies was 1.23 (95% CI: 1.11–1.36), and the RR for chronic obstructive pulmonary disease (COPD) was 1.70 (95% CI: 1.47–1.97) [ 2 ].…”

“…Interventions to reduce indoor air pollution need not be expensive. For example, ventilation is a predictor of indoor NO 2 , and PAH levels are higher in smoking households [ 3 ]. Therefore, free interventions such as smoking cessation and opening windows could reduce the levels of these pollutants.…”