Preliminary Results of a Study 

to Assess Air Quality Impacts 

Associated with Outdoor 

Wood Boiler Use

Judy Abbott

Bureau of Toxic Substance Assessment

NYS Department of Health

December 11, 2009
Presentation Overview

Overview of OWB Study

– Objectives & design

– OWB data analysis

– Preliminary conclusions 

and study limitations

Public Health Nuisance Action
Study Objectives

• To describe air quality (PM2.5) at 

residences near OWB vs. residences 

away from OWB

• To assess influence of meteorological 

conditions (wind direction and 

speed) on measured PM levels
Study Design

Identify OWBs (non-complaint)

– OWBs with building permits in capital 

region

– Additional OWBs identified during field 

reconnaissance

Evaluated data from a PHN action case
Nearfield Sites

<1500 ft radius around OWB

Reference Sites

>2500 ft radius away from OWB

Similar setting 

Study Locations
Materials and Equipment

PM monitors (real-time 

nephelometric PM2.5)

– Thermo DataRAM 4000

– Used inlet heaters to reduce 

influence of humidity

– Retrofit DataRAMs with 

thermoelectric coolers for constant 

temperature and weather protection

Meteorological station -

Davis Vantage Pro2 

portable and solar 

powered

wind direction, speed, 

temperature, rainfall, 

relative humidity
Some Glitches

• Equipment malfunction (e.g., inlet heaters)

• Data loss 

– Daylight saving time

– Power outages

• Ice storm - met station iced

• Residential observation logs
Preliminary Results and 

Data Analysis

• Five non-complaint OWB deployments; one 

complaint OWB (PHN)

• 2007-2008 heating seasons

• Data cleaning and time-matching

Data analysis

• Descriptive statistics

• For each deployment, were case and control 

datasets different?

• Influence of wind direction and speed/calm?
Site 1

Non-complaint

Permitted OWB

Rensselaer County
Site 1. Aerial View of Nearfield site and OWB

OWB

Nearfield
Site 1. Topographical Map of Nearfield (N) and 

Reference (R) sites
Site 1. Longitudinal Graph of PM2.5 Concentrations
Site 1. Longitudinal Graph of PM2.5 Differences 

Difference = [PM]Nearfield - [PM]Reference
Site 1. Mean Difference in PM2.5 by Wind Direction
Site 2

Non-complaint

Permitted OWB

Washington County
Site 2. Aerial View of Nearfield Site and OWB

Nearfield

OWB
Site 2. Topographical Map of Nearfield and 

Reference sites
Site 2. Longitudinal Graph of PM2.5 Concentrations
Site 2. Longitudinal Graph of PM2.5 Differences

Difference = [PM]Nearfield - [PM]Reference
Site 2. Mean Difference in PM2.5 by Wind Direction
Site 6

Public health nuisance complaint

Non-permitted OWB

Ontario County
Site 6. Aerial View of Nearfield site and OWB

Nearfield

OWB
Site 6. Topographical Map of Nearfield and 

Reference Sites
Site 6. Longitudinal Graph of PM2.5 Concentrations
Site 6. Longitudinal Graph of PM2.5 Differences

Difference = [PM]Nearfield - [PM]Reference
Site 6. Mean Difference in PM2.5 by Wind Direction
Summary of Preliminary Air Monitoring Results
Odd Ratios (OR) Concept

Compares whether the probability of a certain event 

is the same for two groups

• OR = 1: the event is equally likely in both groups

• OR > 1: the event is more likely in the first group 

• OR < 1: the event is less likely in the first group
Preliminary Results

* Nearfield geomean PM minus reference geomean PM

“NC” indicates that no odds ratio was calculated because no pollution events were observed when the condition (downwind or calm) was present

“--” indicates that no time-matched meteorological data were available for the monitor pair

“Infinite” indicates that no odds ratio was not calculated because all PM spikes were observed when the condition (downwind or calm) was present

Monitor Distance 

from OWB

(ft)

Mean paired 

difference* 

(ug/m

3

)

Student's

adj pvalue 

(matched 

T-test)

99th 

Percentile 

OR

[nearfield 

minus

reference]

99th 

Percentile OR

(Downwind)

[nearfield]

99th 

Percentile

OR

(Calm) 

[nearfield]

N1 580 4.3 0.01 1.9 NC infinite

N2 260 6.6 <0.0001 33.5 8.5 3.2

N3 681 5.4 <0.0001 6.5 1 5.2

N4 1,270 0.2 0.59 0.6 -- --

N5 350 2 0.0001 3.1 8.3 4.4

N6 150 5.2 0.0001 19.4 infinite NC
Preliminary Results Overview

• PM levels significantly elevated at 5 of 6 monitoring 

locations near OWBs relative to away from OWBs (p  0.01)

• For these five locations:

– Mean PM level increase 2.0 - 6.6 ug/m3 near OWBs 

– PM impacts were observed during late night and early morning hours

– Greatest mean differences when closer to and downwind of OWB 

(flat terrain) or during calms (varied terrain)

– Higher chance of observing extreme PM levels (>95th & 99th 

percentiles)

– Alternative sources did not appear to be significant sources of PM2.5

spikes
Study Limitations

• Limited # OWBs cannot generalize to NYS 

OWB population

• Cannot compare measurements to PM NAAQS 

• Cannot control for all potential confounders

• Target analytes limited to PM
Huge Thanks!!!

Kevin Gleason

Dan Luttinger

Kevin Malone

Kim Mazor

Gerry McDonald

Agnes Mukasa

Gregg Recer

Dan Sharron

Steve Shost

Emily Shusas

Randi Walker

DEC

Dirk Felton

Leon Sedefian

Bob Waterfall

Regional staff

OAG

Judy Schreiber

NESCAUM

George Allen