Climate Change and Respiratory Health

Current Evidence and Knowledge Gaps

Tim K Takaro; Kim Knowlton; John R Balmes

Expert Rev Resp Med. 2013;7(4):349-361.

Infections

The incidence of respiratory infections varies on a seasonal basis. Lower respiratory tract infections have a higher incidence during the winter in temperate areas, but in tropical areas, the incidence of infection is usually higher during the annual rainy season.^[49] A retrospective analysis in Hong Kong showed that the magnitude of summer peaks of influenza. A infections have been increasing over the past decade.^[50] A recent study in China found that multi-day increases in temperature (i.e., lack of cooling at night) were associated with increase emergency department utilization for respiratory tract infections.^[51] Climate change could potentially increase the incidence of childhood pneumonia in tropical settings through several different mechanisms. Increased time indoors because of heavier rainfall could increase crowding and exposure to biomass fuel smoke, and decrease exposure to sunlight (i.e., reduced vitamin D). Population displacement due to drought and famine could further increase the rate of transmission of infections.^[49] Malnutrition due to drought as a result of climate change is likely to increase pneumonia deaths, since a substantial proportion of pneumonia deaths in children under 5 years are attributed to this factor.^[52]

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Table 1. Summary of known and potential respiratory hazards associated with climate change and increase climate variability.
Respiratory hazard impacted by climate change	Known adverse health effects	Potential adverse health effects	Ref.
Increased ozone and particulate air pollution (cook fires, industrial, transportation, forest fires and desert sources)	Reduced lung function, asthma and COPD exacerbation	Increased risk of respiratory infection, abnormal lung development and remodeling, lung cancer, cor pulmonale, enhancement of allergic response	Ozone and PM:;[7,37–46] cook fires:[78] forest fires:;[15–22] infection:[48,49]
Increased temperatures	Increased mortality from respiratory and cardiovascular disease	Increased growth of plant and microbial antigens	Known:;[32–37,64] potential:[52–61]
Aero-allergen production	Increased allergic sensitization, emergency department visits and hospital admissions for asthma and allergic rhinitis	Interaction with air pollutants enhances the allergic response	Known:;[7,8,23–31] potential:[107]
Changes in viral and bacterial respiratory disease patterns		Extended influenza season, shift in optimal microbial ecology, increased crowding	[48–52,113–116]
Reduced agricultural production and maldistribution		Malnutrition and increased risk of respiratory infections	[67,90–92]
Decline in fisheries production		Malnutrition and increased risk of respiratory infections	[90–92]
Extreme weather events and floods	Loss of power for life-support	Increased mold growth and endotoxin	[53–61]
Sea level rise	Flooding: increased refugee camp populations	Coastal flooding and loss of agricultural land to salinification of soils, con-tribution to mold growth	[53–61,125,127]
Forced migration	Ease of spread of respiratory infectious diseases	Conflict and disruptions of services	Known:;[121,123] potential:[9]