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# PM 2.5 

# Concentrations in Residential Outdoor Air Near OWBs

Agnes N Mukasa 1



# , Emily J Shusas 2 

# , Kimberly A Mazor 1 

# , Judith A Abbott 1 

# , Gerald J McDonald 1 

# , Kevin M Malone 1, 

# and Stephen J Shost 1



# . 1 

# New York State Department of Health, Troy, NY; 2 

# New York State Energy Research & Development Authority, Albany, NY

SUMMARY RESULTS

– WIND SPEED & DIRECTION

CONCLUSIONS RESULTS

– PM 2.5 

# POLLUTION EVENTS

Although these investigations considered only six residential locations near OWBs, study results indicated that OWBs can significantly increase PM 2.5 

# concentrations in outdoor air at nearby residences. The study did not employ regulatory air monitors, so measured PM 2.5 

# levels were not 

# compared to air quality standards. None the less, the severity of adverse

health effects associated with even short

- duration elevated PM 2.5 

# air concentrations, along with the demonstrated importance of OWBs as

sources of wood smoke and PM 2.5 

# in some residential settings, indicate that further efforts to reduce exposures to OWB

- derived wood smoke and

PM 2.5 

# are warranted. Geometric mean (GM) 5

- or 10

- minute average fine particulate (PM 2.5 

# ) concentrations were statistically significantly elevated at 5 of 6 nearfield monitors, located 150 to 1,270 feet distant from the nearest Outdoor

Wood

- Fired Boiler (OWB), compared with paired reference monitors located in the same general area

-- but at least 2,500 feet distant from the nearest OWB ( p = <0.0001

– 0.01). GM PM 2.5 

# level increases of 15, 17, 46, 74 and 187 percent were calculated. Relative odds of observing an extreme (>95 th 

# percentile) PM 2.5 

# concentration were 1.8

- to 4.3

- fold higher at the 5 nearfield monitors, and increases were statistically significant ( p = <0.0001

– 0.043). Calm (0 m.p.h.) winds were statistically significantly

associated with increased r elative odds of observing an extreme PM 2.5 

# concentration difference (nearfield PM 2.5 

# minus reference PM 2.5 

# ) at four of

the five sites. Downwind status was s tatistically significantly associated

with increased r elative odds of observing an extreme PM 2.5 

# concentration difference at 3 of the 5 sites. In summary, residence near OWBs was associated with substantially increased GM PM 2.5 

# levels and numbers of

PM 2.5 

# pollution events. PM 2.5 

# pollution episodes at a residence near an OWB can be associated with calm periods, downwind status, or both.

OWBs (Fig. 1) can be substantial sources of wood smoke and associated

PM 2.5 

# . A 2006 report issued by the Northeast States for Coordinated Air Use Management indicated that average PM 2.5 

# emissions (grams per hour) from one OWB are equivalent to the emissions from 22 US EPA

certified wood stoves, 205 oil furnaces, or as many as 8,000 natural gas

furnaces.

During the 2007 and 2008 heating seasons, New York State Department of Health (NYS DOH) investigators conducted an air monitoring study to evaluate the potential for smoke from OWBs to increase outdoor air PM 2.5 

# levels in residential neighborhoods. This was accomplished by comparing PM 2.5 

# concentrations in air at residences near OWBs to levels in air at residences distant from OWBs, and then by determining if unusually elevated PM 2.5 

# concentrations reported in air at residences near



# BACKGROUND

As indicated in Table 2, calm winds were common at the 5 study sites reporting wind speed and direction data, but 2 nearfield monitors were only rarely downwind of nearby OWBs.



# RESULTS

– TIME CALM & DOWNWIND Monitor

Pair Instrument

Pair Monitoring Period Distance Between

Nearfield Monitor & OWB(s) ( ft ) PM 2.5 Data

Log Intervals (min) OWB Status

N1/R1 DR2/DR1 02/19/08

- 03/04/08 390, 500, 580,

1420 10 non

- permitted/no complaints

N2/R2 DR1/DR2 03/12/07

- 03/26/07 260 5 permitted/no complaints

N3/R3 DR1/DR2 03/20/08

- 04/10/08 680 10 non

- permitted/no complaints

N4/R4 DR2/DR1 03/30/07

- 04/20/07 1270 5 permitted/no complaints

N5/R5 DR1/DR2 01/07/08

- 01/28/08 350, 1180 10 permitted/no complaints

N6/R6 DR2/DR1 03/06/08

- 03/13/08 150 10 non

- permitted/complaints 

# Table 1. Summary of air monitor deployments

.

Monitor

Pair Time

- Matched

PM 2.5 Concentrations (n) Time

- Matched PM 2.5

Concentrations with

Time

- Matched Meteorological Data (n) Percent of Monitoring

Time

Downwind ( Nearfield ) Percent of

Monitoring

Time Winds

Calm (Nearfield)

N1/R1 1,914 1,802 13.3 % 54.3 %
N2/R2 3,373 3,344 17.7 % 20.5 %
N3/R3 2,689 2,685 1.9 % 28.3 %
N4/R4 4,004 0

-- -- N5/R5 3,001 2,687 4.1 % 33.8 %
N6/R6 970 820 28.1% 24.8% 

# Table 2. Summary of time

- matched PM 2.5 

# monitoring data

. 

# Figure 3 Boxplots of time

- matched PM 2.5 

# concentrations.

Monitor

Pair Nearfield Monitor

Geometric Mean PM 2.5 Concentration ( μg /m 3 ) Reference Monitor

Geometric Mean

PM 2.5 Concentration ( μg /m 3 ) Mean Paired

PM 2.5 Concentration

Difference ( μg /m 3 ) Student's

p

N1/R1 11.5 9.8 4.3 0.01

N2/R2 15.8 9.1 6.6 <0.0001

N3/R3 6.6 2.3 5.4 <0.0001

N4/R4 3.2 4.4 0.2 0.59

N5/R5 9.8 8.5 2.0 <0.0001

N6/R6 13.3 9.1 5.2 <0.0001 

# Table 3. Comparisons of PM 2.5 

# concentrations at nearfield monitors and corresponding reference monitors

.

Table 4. Relative odds of observing a 95th percentile or greater PM 2.5 

# concentration (PM 2.5 

# pollution event) at each nearfield monitor compared with its corresponding reference monitor, with 95% confidence intervals and 

# regression p

- values

.

Site 95th Percentile PM 2.5

Concentration Cutpoint ( μg /m 3 ) Odds Ratio 95% Confidence

Interval logit p

NEARFIELD

1 56.3 1.9 1.1, 3.1 0.016

2 46.9 1.8 1.2, 2.6 0.004

3 15.6 4.3 2.6, 7.1 <0.0001

4 13.5 0.8 0.5, 1.2 0.22

5 26.2 1.8 1.3, 2.5 0.0001

6 37.8 2.0 1.02, 3.8 0.043 Site CALM (2)

Odds Ratio (95% CI) CALM (2)

logit

p DOWNWIND (3)

Odds Ratio (95% CI) DOWNWIND (3)

logit

p

1 21.0 (2.8, 155.4) 0.003 0.24 (0.03, 1.8) 0.17

2 2.1 (1.4, 3.1) 0.0002 1.7 (1.1, 2.6) 0.009

3 2.7 (1.7, 4.3) <0.0001 2.0 (0.7, 5.3) 0.17

5 4.5 (2.9, 7.0) <0.0001 4.0 (2.2, 7.1) <0.0001

6 0.8 (0.3, 2.1) 0.69 5.9 (2.6, 13.6) <0.0001 

# Table 5. Relative odds of observing a 95th percentile or greater paired

PM 2.5 

# concentration difference at each study site that provided time

matched meteorological data, with 95% confidence intervals and logistic regression p

- values (1)



# .

Figure 2

. DataRAM and Dustscan monitors ready for deployment.

Note : The study employed only DataRAM data.



# Fig. 3 & Table 3 indicate that at five of six deployments, GM PM 2.5 

# levels were higher at residences near OWBs than at more distant residences. Table 3 indicates that the increases were statistically significant. The possibility that local roads and homes contributed to elevated PM 2.5 

# levels observed around study OWBs cannot be ruled out, although there is evidence that such contributions were negligible. Specifically, other studies

have determined that PM 2.5 

# emissions from vehicles, and primary home heating systems common in rural NYS, are considerably lower than emissions from OWBs (Gillies et al., 2001; NESCAUM, 2006). In as much as OWBs are often employed as primary home heating sources, home heating system flues at OWB owners' residences probably emitted minimal, if any,

PM 2.5 

# . With regard to fireplace emissions, no chimney smoke was observed at any OWB owner's home, nearfield monitor location, or reference monitor location over the course of the study, despite frequent site visits. 

# METHODS (CONTD.)

Table 5 indicates that at 4 sites, calm winds were associated with statistically significant 2.1

- to 21

- fold increased relative odds of observing an extreme (>95 th 

# percentile) PM 2.5 

# difference. As expected, calm winds often occurred at night, so that at 4 sites the relative odds of observing an

extreme PM 2.5 

# concentration were elevated at night (data not shown). At 3 sites, downwind status was associated with statistically significant 1.7

- to

5.9

- fold increased relative odds of observing an extreme (>95 th 

# percentile)



# difference. Notes : (1) Odds ratios, confidence intervals and p

- values were adjusted for autocorrelation. (2) “CALM” indicates that the mean nearfield wind speed was 0 mph (3) “DOWNWIND” indicates that the nearfield monitor was approximately downwind of a nearby outdoor wood

- fired boiler.



# ALTERNATIVE PM 2.5 

# SOURCES

Table 4 indicates that at the 5 sites where nearfield GM PM 2.5 

# levels were statistically significantly elevated, proximity to one or more OWBs was associated with a statistically significant 1.8 to 4.3

- fold increased relative odds of observing a PM 2.5 

# pollution event.



# RESULTS

– PM 2.5 

# LEVELS COMPARED

METHODS Figure 1 . A study OWB

in operation. OWBs coincided with wind conditions favoring local accumulation of OWB smoke (e.g., calm winds), or transport of OWB smoke towards the monitors.

NYS DOH staff deployed DataRAM Model 4000 air monitors (Fig. 2) to

record 5

- or 10

- minute average PM 2.5 

# concentrations at several residential properties near operational OWBs. Two nearfield monitors were deployed within 1,500 feet of multiple OWBs (Table 1). Deployments lasted for one to three weeks per study site. Student’s t

- test was employed to evaluate GM differences, and logistic regression (logit) was used to evaluate pollution episodes. Statistical tests adjusted for autocorrelation and employed an α of

0.05.