3.4. Health impact estimates
The US Environmental Protection Agency primary standard for unhealthy levels of annual average PM
2.5 is 12
μg m
−3. According to the World Bank, much of Equatorial Asia is close to this standard in non-haze years—e.g., annual mean values reported for 2011 are 13–14
μg m
−3 for Indonesia, Malaysia, and Singapore (
PM2.5 air pollution, mean annual exposure (micrograms per cubic meter) | Data). Based on smoke exposures for 2006 (section
3.2), we estimate the following excess deaths for that year, with 95% confidence intervals calculated as in Driscoll
et al (
2015): 34 600 (9000–60 100) in Indonesia, 2300 (600–4000) in Malaysia, and 700 (200–1200) in Singapore. For 2015, we estimate these excess deaths to be: 91 600 (24 000–159 200) in Indonesia, 6500 (1700–11 300) in Malaysia, and 2200 (600–3800) in Singapore. (See supplement section
2 for description of the health impact calculations and comparison to previous estimates for the 1997 event.) Our results suggest that regional smoke-related mortality was 2.7 times higher in 2015 than in 2006, an increase whose causes we summarize in the discussion and conclusions.